Enterprise Forever

:UK => Hardware => Interface => Topic started by: Saint on 2013.September.03. 12:26:10

Title: Internal memory expansion
Post by: Saint on 2013.September.03. 12:26:10
Are the pinouts of EXP1 and EXP2 in the schematics anywhere? I looked last night and couldn't see them...
Title: Re: Internal memory expansion
Post by: Zozosoft on 2013.September.03. 12:28:16
Look at the pinouts (http://enterprise.iko.hu/pinouts.htm) :-)
Title: Re: Internal memory expansion
Post by: Saint on 2013.September.03. 12:48:55
Damn, I should have thought of that! :oops:
Title: Re: Internal memory expansion
Post by: Zozosoft on 2013.September.03. 13:00:26
Quote from: Saint
Damn, I should have thought of that! :oops:
:-)

Are you going to build memory expansion for the spare machine?
Title: Re: Internal memory expansion
Post by: Saint on 2013.September.03. 13:15:09
Yes, that's what I was thinking. Should be simple with an SRAM chip and a PAL for address decoding. With surface mount components it would be a tiny board, and you could have a large memory expansion (like your modified expansion card). The space above EXP2 is a bit tight though -- was hoping it could just be pin headers for both connectors. Looks like you need ribbon for EXP2, like the original memory expansion.
Title: Re: Internal memory expansion
Post by: Saint on 2013.September.03. 18:23:57
So this is how I understand the memory expansion works:

MREQ is used to trigger the RAS / CAS delay capacitors to the address multiplexers when A16 is high and A17-21 are low and /RD or /WR are low. This feeds the address to the 4164 chips with suitable RAS / CAS delays. Quite neat.

So a read or write in the memory range of 0x1xxxx will access the internal memory expansion.

For a modern SRAM based memory expansion you'd just need to decode A16-A21 as you like for the SRAM size (from 0x10000 up), then enable the SRAM when MREQ is low and read or write are low.

I'm not that familiar wit the Z80, so if you could sanity check for me Zozo? :)
Title: Re: Internal memory expansion
Post by: Zozosoft on 2013.September.03. 18:41:37
Interfacing SRAM or Flash ROM are very simple task. For 512K chips enought one 74HCT138 for address decoding. A0-A18 go directly to the memory chip, A19-A21 to the 138 inputs (A-B-C). MREQ to 138 low level enable (G2A&G2B), RFSH to 138 high level enable (G1) (no access at Refresh). RD and WR to memory WE and OE. One of the 138 outputs to memory CE.
Title: Re: Internal memory expansion
Post by: Saint on 2013.September.03. 23:05:16
Ok, that makes sense. How does the memory mapping work from A0-A21 to segment numbers?

The internal 64K RAM expansion seems to decode A21-A16 = 000001b, or 0x1nnnn. Ah, I have that inverted because it's an active low input, so it should be 111110b? Which would be segment F8, which makes more sense... :)

So if I wanted to map 512K SRAM to an internal memory expansion which would include segments F8-FB, could I use A21-A19 = 111b and just waste 64KB of the SRAM without causing any problems?

Edit: Hmm, it looks like the /ACCESS line of the Nick drives the data bus on VRAM access. So I would need to ensure the internal RAM expansion does not drive the data bus in segments FC-FF?
Title: Re: Internal memory expansion
Post by: Zozosoft on 2013.September.03. 23:20:56
Quote from: Saint
So if I wanted to map 512K SRAM to an internal memory expansion which would include segments F8-FB, could I use A21-A19 = 111b and just waste 64KB of the SRAM without causing any problems?
It mirrors the video RAM, reading can be conflicted, but as both outputs contain the same data, practically no problem. The prototype Bugtronics 512K expansion worked the same way.

The trick to decode for DC to FB can be done with some more ICs
Title: Re: Internal memory expansion
Post by: Saint on 2013.September.03. 23:26:43
Quote from: Zozosoft
With some more ICs can do the trick to decode for DC to FB.
I'll have a think about that! :)

If you can safely drive the bus with FC-FF being a mirror, then that's a really simple address decoder. I'll see how easy a PAL would be to decode the address properly...
Title: Re: Internal memory expansion
Post by: Zozosoft on 2013.September.03. 23:34:38
Probably one additional 74HCT151 can do the trick, using similar method as the 320K modifications.
Title: Re: Internal memory expansion
Post by: Bagpuss22 on 2013.September.04. 13:38:54
If you are interested I have a spare official enterprise 64K expansion board.  
I was going to upgrade my EP64 but I decided to buy an EP128 instead!

Russ
Title: Re: Internal memory expansion
Post by: Saint on 2013.September.04. 15:31:48
Thanks for the offer Russ, but I'm more interested in doing this for the experience of making some interesting little hardware projects! There probably wont be much (any?!) call for new RAM expansion boards for the Enterprise, but if I order some PCB's then there will be some spare I can sell to other folks with an EP. A 512KB expansion looks like it will probably cost less than £10 in components.
Title: Re: Internal memory expansion
Post by: Bagpuss22 on 2013.September.04. 17:04:59
No rpoblem.

That sounds good, £10!  I might be interested in something like that to upgrade my EP128!
Title: Re: Internal memory expansion
Post by: Saint on 2013.September.04. 22:55:19
Quote from: Zozosoft
Probably one additional 74HCT151 can do the trick, using similar method as the 320K modifications.
I've had a look at old PAL chips and you can get GAL16V8 chips cheap from China, so I've got some of those on order. Works out about 40p a chip, which will do the whole address decode and memory access very neatly:

/CE = !(A21 & A20 & (A19 ^ (A18 & A17 & A16)) & !/MREQ & /RFSH)

Very old technology, but perfect for the job! :)
Title: Re: Internal memory expansion
Post by: Zozosoft on 2013.September.05. 09:38:58
You know how can write program for PAL/GAL?
Title: Re: Internal memory expansion
Post by: Saint on 2013.September.05. 10:01:45
Yes, you can use a few different tools, but I've had a look at WinCUPL. The code for the address decode is --

/* *************** INPUT PINS *********************/

PIN 1    = A21 ;
PIN 2    = A20 ;
PIN 3    = A19 ;
PIN 4    = A18 ;
PIN 5    = A17 ;
PIN 6    = A16 ;
PIN 7    = _MREQ ;
PIN 8    = _RFSH ;
 
/* *************** OUTPUT PINS *********************/

PIN 12    = _EN ;

/***************** EQUATIONS ***********/

_EN = !(A21 & A20 & (A19 $ (A18 & A17 & A16)) & !_MREQ & _RFSH);


You can probably use your eprom programmer to program the PAL. My eprom programmer is so old it needs a parallel port and Windows XP, so I think I'm going to have to buy a new programmer which works with USB and Win7 x64!
Title: Re: Internal memory expansion
Post by: Zozosoft on 2013.September.05. 10:17:26
Quote from: Saint
Yes, you can use a few different tools, but I've had a look at WinCUPL. The code for the address decode is --
Thanks! It looks very simple, great!
I think the Spectrum Emulator card (http://gafz.enterpriseforever.com/Hardware/PCB/Picture/Emulatorjav.jpg) can be very reduced with GALs :-)

Quote
You can probably use your eprom programmer to program the PAL.

Yes, my program (http://www.elnec.com/products/device-programmers/labprog-plus/) can program PAL/GAL. (It is also, old but works under W7 x64, I just put a PCI LPT card to my PC :-) )
Title: Re: Internal memory expansion
Post by: Saint on 2013.September.05. 10:25:38
Annoyingly I only have a small shuttle case, and both of my PCI slots are used up by my graphics card! :mad:
Title: Re: Internal memory expansion
Post by: Saint on 2013.September.11. 15:10:26
I found some time last night to do the schematic and PCB layout for a 512KB SRAM expansion using a PAL for address decoding. It's come out really nicely -- less than 5cm square. Which means I can get it fabricated extra cheaply in China! :)

I was going to wait until I got my PCB's back from my HDMI project, but I may just go ahead and order these as well now, as it's only going to cost something like £12 to get 10 boards made.

PCB mock-up below!
Title: Re: Internal memory expansion
Post by: Zozosoft on 2013.September.11. 15:15:46
Nice! :smt041
Title: Re: Internal memory expansion
Post by: Bagpuss22 on 2013.September.12. 16:04:25
Very Nice.......

I agree with Zozo that it would be good to see if the Spectrum Emulator can be
addressed in the same way.....

Russ
Title: Re: Internal memory expansion
Post by: Saint on 2013.September.12. 16:30:58
Quote from: Bagpuss22
Very Nice.......

I agree with Zozo that it would be good to see if the Spectrum Emulator can be
addressed in the same way.....

Russ
Yeah, I had a quick look at the schematics for the spectrum emulator last night as bedtime reading... :)

I'll see if I can understand what it's doing and come up with a modern take on it.

I've been thinking about the SD card <> PIC interface and a 5v tolerant CPLD (the Altera MAX 3000A is my preference) is by far the easiest and cheapest way of doing it. I believe the spectrum emulator would be the same solution, it would all fit in one CPLD.

You may even be able to fit a spectrum emulator into the CPLD with the PIC interface, as I dont believe it's very complicated!
Title: Re: Internal memory expansion
Post by: lgb on 2013.September.12. 17:36:32
Quote from: Saint
I've been thinking about the SD card <> PIC interface and a 5v tolerant CPLD (the Altera MAX 3000A is my preference) is by far the easiest and cheapest way of doing it. I believe the spectrum emulator would be the same solution, it would all fit in one CPLD.

You may even be able to fit a spectrum emulator into the CPLD with the PIC interface, as I dont believe it's very complicated!

If you want to use a CPLD maybe it should be considered to implement a general SPI interface in CPLD without the help of an MCU at all. Well it sounds odd, but somehow I always feel it's a bit cheating like action to connect an MCU to a 8 bit machine having more powerless CPU than the MCU itself ... The only disadvantage of this is the fact that you have to implement SD card init sequence and handling by Z80 code itself, directly. But it's a more "the EP is the boss" feeling then :) By the way, for 65xx bus system there is an existing "product" for creating an SPI interface "chip" with the help of CPLD with a Xilinx part (xc9572), the name of the project is 65SPI. Similar solution can be created for the EP bus too. Of course, if you have spare gates available, you can implement extra stuffs as well, like logic of a Spectrum emulator, etc :)
Title: Re: Internal memory expansion
Post by: Saint on 2013.September.13. 10:33:59
Hmm, as the CPLD is obviously reprogrammable, what I could do is hook up all the useful signals from the bus to the CPLD and have quite a generic Enterprise hardware expansion. You could have headers for I/O lines which could be used for a generic SPI interface, and a PIC chip for other more complex tasks. The PIC itself can be reprogrammed to provide other functionality as well if required, or removed altogether if you wanted to do the SD card SPI work on the EP.

I'll have a think about that... it would turn quite a few hardware expansions into a much simpler VHDL programming job.
Title: Re: Internal memory expansion
Post by: lgb on 2013.September.13. 10:47:13
I also wanted to create an SD-interface solution with the help of an MCU (AVR, not PIC, but it's matter of personal taste and knowledge only). I would prefer CPLD (for various reasions including the feeling of using an MCU with a 8 bit computer, as I've told), the only problem that I am totally dumb for programming hardware decription lanugages (ie VHDL and/or Verilog) while I can write code for AVR at least using both of C or AVR assembly ...
Title: Re: Internal memory expansion
Post by: Saint on 2013.September.13. 20:25:58
I've ordered a batch of 10 pcb's now, for the bargain price of under £10. At that price I couldn't resist. :) Now I just have to wait for about 5 weeks for them to turn up.

I also added a spare pad for A15 as I plan to install Zozo's updated EXOS ROM with the expansion. It'll give me an easy place to connect up the missing address line.
Title: Re: Internal memory expansion
Post by: Zozosoft on 2013.September.13. 22:18:36
Quote from: Saint
I've ordered a batch of 10 pcb's now, for the bargain price of under £10.
Where you order?
Title: Re: Internal memory expansion
Post by: BruceTanner on 2013.September.13. 22:29:50
Quote from: Zozosoft
Where you order?
I would be interested to know that too!
Title: Re: Internal memory expansion
Post by: Saint on 2013.September.13. 22:42:38
I have placed a couple of orders with :

http://www.tinyosshop.com/

I haven't had any boards through yet, so I don't know the quality, but I've seen quite a few good comments about them on the web. For the price I figured it was worth a go. It works out cheaper than making the boards myself, and you get through hole plating and solder mask! Plus it means I can do vias under SMD components which makes life a lot easier. :D
Title: Re: Internal memory expansion
Post by: Bagpuss22 on 2013.September.13. 22:57:22
Looks really good and a very good price too!  :cool:
Title: Re: Internal memory expansion
Post by: Zozosoft on 2013.September.13. 23:08:49
Which program used for the PCB design?
Title: Re: Internal memory expansion
Post by: Saint on 2013.September.13. 23:20:39
I've been using Altium Designer, it's very nice. I find it much easier than Eagle, which I used before. The 3d view of the board (the mockup shot from earlier in the thread) is really nice too.
Title: Re: Internal memory expansion
Post by: Saint on 2013.September.14. 17:53:02
I just got my PCB's back from my HDMI project, they are VERY nice! And arrived much quicker that I expected -- I think it took about 2 weeks from placing the order. I've attached a scan, so if anyone else is thinking of using them you can see what you get!

And this board had a load of channels cut as well for detaching multiple PCB's from the one main board.

Excellent!! :D
Title: Re: Internal memory expansion
Post by: Zozosoft on 2013.September.14. 20:37:18
It looks very good!
Title: Re: Internal memory expansion
Post by: Saint on 2013.September.14. 23:57:24
I like designing with surface mount components, but trying to solder these 0.5mm pitch chips by hand is a bloody nightmare! I don't think I have the knack yet. More practice needed. Still, I have one chip soldered after about an hour!! :o

I'm glad I went 'old school' and used all through hole components for the EP memory expansion. :D
Title: Re: Internal memory expansion
Post by: Zozosoft on 2013.September.15. 00:21:48
Quote from: Saint
I'm glad I went 'old school' and used all through hole components for the EP memory expansion. :D
Good idea!
Title: Re: Internal memory expansion
Post by: Saint on 2013.October.10. 14:07:26
My PCB's arrived today! Looking good.

I'm just missing the GAL's to be able to assemble the board entirely. I'll probably get an expensive GAL locally until I can get some cheaper from China to make the rest of the boards up.
Title: Re: Internal memory expansion
Post by: Zozosoft on 2013.October.10. 14:48:01
Quote from: Saint
My PCB's arrived today! Looking good.
Nice!
Title: Re: Internal memory expansion
Post by: BruceTanner on 2013.October.10. 14:51:05
Quote from: Saint
My PCB's arrived today! Looking good.
Two tracks between pads - you'd never do that by hand!
Title: Re: Internal memory expansion
Post by: Saint on 2013.October.10. 22:33:14
The first PCB built up! I've ordered a GAL from the UK, which I should get in the next couple of days. All going well I should have a working 512KB expansion in a few days.

I've built the memory expansion to be removable (all on header pins) such that I can fully test each new unit I make, and also have the ability to make other internal cards and easily install them if needed. My internal SD card hard drive and combined memory expansion being one I want to make... :)
Title: Re: Internal memory expansion
Post by: Mayer Gábor on 2013.October.11. 00:04:43
Could you please show me a photo of your motherboard with these pins?
Title: Re: Internal memory expansion
Post by: Saint on 2013.October.11. 10:34:53
I will take a photo of the motherboard later on today. I've fitted a header socket into EXP1 and a ribbon with 10way connector into EXP2 (all of which will be provided with the memory upgrade kit).

I've priced up the finished kit, and assuming I get my GAL chips from China eventually, then I can sell them at £15 + P&P. A bargain knock-down price for Enterprise Forever users! I'll put some on eBay at a higher price and see if I can make a few more pounds to fund the SD card interface work.

This is assuming it works of course! Lol. :lol:
Title: Re: Internal memory expansion
Post by: Saint on 2013.October.11. 15:10:25
This is the motherboard.

Title: Re: Internal memory expansion
Post by: Zozosoft on 2013.October.11. 15:51:16
Quote from: Saint
This is the motherboard.
Nice!
Title: Re: Internal memory expansion
Post by: Bagpuss22 on 2013.October.11. 18:11:51
Looking really good!  When they become available please count me in! :cool:
Title: Re: Internal memory expansion
Post by: Saint on 2013.October.15. 22:53:30
I have received my GAL's both from my UK source and China now! Amazingly I've just populated my PCB with SRAM and the programmed address decoding PAL and it's working! Counts all the way back to DC. :ds_icon_cheesygrin:

I now need to install Zozo's EXOS with fast memory checking! Is it normal to see "ERROR" flash up to the right of the memory checking when it finishes? It only flashes up very quickly, and not every time, but I've seen this both with just internal RAM and with the expansion, so I'm assuming it's when it reaches an address which isn't RAM?

I'll build up some more boards soon and let people know when they're ready for purchase. 

Very pleased. SD card interface next... :smt041
Title: Re: Internal memory expansion
Post by: Zozosoft on 2013.October.15. 23:30:21
Quote from: Saint
I now need to install Zozo's EXOS with fast memory checking!
Good idea! :-)
Also try the Advanced Test.

Quote
Is it normal to see "ERROR" flash up to the right of the memory checking when it finishes?
Can you see "xxx bytes not working" in the BASIC?
If no, then there is no error. You can see it only when the palette of Status Line changed before the old text cleared.
Title: Re: Internal memory expansion
Post by: Saint on 2013.October.16. 00:18:01
2.32uk installed! :)

Working great, all RAM tests (slow, normal, fast) are working fine and are showing 576KB of memory. Very nice job Zozo, much quicker than the normal bootup and so many more nice options!

I'm not seeing any "bytes not working" messages, 589824 bytes in system and 574766 bytes unused. :ds_icon_cheesygrin: That must have just been a flash of "ERROR" I saw with the palette change, as you say Zozo.

All working well, very pleased! I had to cut the tails on the keyboard membrane to get it working, though, as the previous user had made a mess of re-inserting them the last time. Getting a bit short!! :shock:

I could now do with getting my disk controller working so I can test some software...

Looking forward to having the SD card hard drive.
Title: Re: Internal memory expansion
Post by: Zozosoft on 2013.October.16. 08:00:58
Quote from: Saint
2.32uk installed! :)
Also try the EXOS 2.4 beta 3! (http://enterpriseforever.com/programozas/exos-2-3-tovabb-fejlesztese/?action=dlattach;attach=9083) which contains the new Advanced Test mode.
Title: Re: Internal memory expansion
Post by: Saint on 2013.October.17. 00:10:44
I built up and tested two units tonight. I'll get the other bits together tomorrow (header + connector), then they're ready for whoever wants them. I'll put some instructions together as well -- it's fairly simple, but can be a bit fiddly clearing out solder from existing holes.

I have Bagpuss22 and geo1977 down as interested. I'll drop you chaps a message tomorrow, anyone else let me know if you're interested and I'll get some more units built up soon.

They are £15 + P&P via PayPal (as gift) for anyone interested. Postage in the UK shouldn't be much, anyone overseas please let me know where you are and I'll find out the postage cost.
Title: Re: Internal memory expansion
Post by: Zozosoft on 2013.October.17. 09:30:20
I want a 3!

Can you post photos of the finished board?
Title: Re: Internal memory expansion
Post by: BruceTanner on 2013.October.17. 10:27:57
I'd quite like one (UK). Can build it up myself if that's easier for you but would need a programmed GAL and PCB of course!

B.
Title: Re: Internal memory expansion
Post by: Saint on 2013.October.17. 10:47:49
No problem Zozo & Bruce, I'll order some more bits and get building! :ds_icon_cheesygrin:

I will post pictures of the full "kit" later on today with the board and headers / connectors that come with it.

I'll build the boards up and test them before shipping out, as I want to be sure I don't send anything out dead! These PCB's were only 50% e-tested, and the ones which were tested (if they even were?!) don't appear to be marked. I inspect each PCB before building it up, but am not 100% confident until they're tested as spotting errors on these small traces is a little tricky. :shock:
Title: Re: Internal memory expansion
Post by: Zozosoft on 2013.October.17. 10:54:59
Quote from: Saint
I'll build the boards up and test them before shipping out, as I want to be sure I don't send anything out dead! These PCB's were only 50% e-tested, and the ones which were tested (if they even were?!) don't appear to be marked. I inspect each PCB before building it up, but am not 100% confident until they're tested as spotting errors on these small traces is a little tricky. :shock:
Then I highly recommend the Advanced Test in EXOS 2.4 beta!
Title: Re: Internal memory expansion
Post by: Saint on 2013.October.17. 11:04:28
Quote from: Zozosoft
Then I highly recommend the Advanced Test in EXOS 2.4 beta!
Thanks, Zozo, I will run that over all the boards. Any problems on the PCB should result in fairly obvious failure, though. It'll be either broken traces or possible shorts!
Title: Re: Internal memory expansion
Post by: Zozosoft on 2013.October.17. 11:22:36
Quote from: Saint
It'll be either broken traces or possible shorts!
Broken or short circuited address lines can result very mystic errors, for example the frst 256K shadows the other 256K. In the original tests only checked each segment alone and not discovered if one segment overwrite another.
I placed many tricks to the advanced test for discover this type errors.
(But also a basic trick in the Quick Test, it is left the segment number plus inverted segment number at the first two bytes of the segment, after tested it. And in the final phase these verfied back, if it overwrited then report as bad segment)
Title: Re: Internal memory expansion
Post by: fatbob_gb on 2013.October.17. 14:14:47
I am interested in getting one of these if you have any spare
Title: Re: Internal memory expansion
Post by: Saint on 2013.October.17. 22:46:12
Yes, you are right about the address lines, Zozo, I'll be sure to test them all with 2.4! :)

Fatbob_gb, no problem. I have 10 pcb's to make up, I think that's 7 spoken for now, plus one for myself. I may end up getting some more pcb's made at this rate...

Here's a picture of what you'll be getting. The main expansion board, a 14x2 header to install into EXP1 and a 10 way connector with ribbon to install into EXP2.

The most awkward part of the whole job is clearing the solder from the EXP1/2 through holes on the pcb. I've never been that good with a solder sucker!
Title: Re: Internal memory expansion
Post by: Zozosoft on 2013.October.17. 23:08:34
Quote from: Saint
The most awkward part of the whole job is clearing the solder from the EXP1/2 through holes on the pcb. I've never been that good with a solder sucker!
I think can be done less than 5 minutes :-)

Quote
I have 10 pcb's to make up, I think that's 7 spoken for now, plus one for myself. I may end up getting some more pcb's made at this rate...
I will ask in the Hungarian forum, how many users interested.
Title: Re: Internal memory expansion
Post by: Saint on 2013.October.17. 23:16:47
I think can be done less than 5 minutes :-)
I will ask in the Hungarian forum, how many users interested.

You are much better than me with a solder sucker if you can do this in under 5 minutes! :lol:

Thanks, Zozo, happy to make up some more. It's nice to think I'm helping keep the Enterprise alive! :)
Title: Re: Internal memory expansion
Post by: Zozosoft on 2013.October.17. 23:19:48
Quote from: Saint
You are much better than me with a solder sucker if you can do this in under 5 minutes! :lol:
Complete Z80 replace less than 10 minutes :-D
Title: Re: Internal memory expansion
Post by: fatbob_gb on 2013.October.17. 23:31:06
Quote from: Saint
It's nice to think I'm helping keep the Enterprise alive! :)
Thanks for the effort that you are putting in - It is appreciated.
My Enterprise is possibly the most neglected machine that I own but soon it will be getting the attention that it deserves.
Title: Re: Internal memory expansion
Post by: Bagpuss22 on 2013.October.17. 23:38:15
I second that, thank you for this and I look forward to the other bits and pieces
that you are looking at producing!

:smt023
Title: Re: Internal memory expansion
Post by: Starship on 2013.October.18. 09:22:33
Please can you let me know when you will have the combined Memory Expansion and SD card interface ready for purchase....you have one buyer here!


Starship
Title: Re: Internal memory expansion
Post by: Zozosoft on 2013.October.18. 09:53:17
Current summary for Hungary: 6! (Zozo, Szalai56, Z80System, Lacika)
For reducing the shipping cost, I will do the business with you, then forward for my friends in Hungary.

Can you calculate the shipping cost with Royal Mail International Signed For service?
Title: Re: Internal memory expansion
Post by: Saint on 2013.October.18. 10:44:41
Quote from: Zozosoft
Can you calculate the shipping cost with Royal Mail International Signed For service?
No problem, Zozo, I'll sort that out for you. I'm going to figure out postage costs this evening. With the new orders from Hungary that's the whole 10 units gone! I'll order some more PCB's... :)

Quote from: Starship
Please can you let me know when you will have the combined Memory Expansion and SD card interface ready for purchase....you have one buyer here!


Will do! The SD card interface will be some time away yet as I've only got as far as the planning stage. However it's the most important thing that is needed on the Enterprise, so I want to make it happen.
Title: Re: Internal memory expansion
Post by: Saint on 2013.October.18. 22:57:05
Just a quick update on postage costs for a single unit if anyone else is interested --

UK
Royal Mail first class, £3.00
Royal Mail signed for, £4.10

Airmail
Airmail Small Packets, £3.00
International Signed For Small Packets, £8.30

I'm just going to double check the two boards going out with the latest 2.4 memory checker, then they will be shipped out once payment is made.

I'm waiting on some more right angled headers which should turn up tomorrow, then I think I have everything to make up the rest of the boards. Hopefully will have all 10 built up next week. Going to place an order for another 10 PCB's now... :)

Update -- all boards tested perfectly with advanced test, new batch of 10 PCB's ordered!
Title: Re: Internal memory expansion
Post by: Bagpuss22 on 2013.October.19. 00:26:54
Looking forward to doing this, quite excited! :smt023

Just got to get this 16K Spectrum sorted over the weekend and then I am ready!
Title: Re: Internal memory expansion
Post by: Zozosoft on 2013.October.19. 00:33:19
Quote from: Saint
all boards tested perfectly with advanced test
Great!
Title: Re: Internal memory expansion
Post by: geo1977 on 2013.October.19. 02:55:51
We are OK!!!!!!!!!!!!! i wating my memory working with my enterprise:lol::smt039
Title: Re: Internal memory expansion
Post by: Zozosoft on 2013.October.19. 17:38:11
Quote from: Saint
new batch of 10 PCB's ordered!
When do you think the second batch available?

Current orders from Hungary: 8!
Title: Re: Internal memory expansion
Post by: Saint on 2013.October.19. 21:18:51
When do you think the second batch available?

Current orders from Hungary: 8!

Great! :) I also saw in the Hungarian thread people talking about memory expansions larger than 512KB. Is this something that people would want? I may be able to get some larger SRAM if there is interest, although it all takes time to get the PCB made, etc.

The lead time on the PCB's is around 3 weeks. Plus I have ordered some more GAL's, which are the slowest thing to arrive. The last lot took 40 days!! I ordered them about 7 days ago, so I have a feeling I am going to be waiting for the GAL's to arrive again... :(
Title: Re: Internal memory expansion
Post by: lgb on 2013.October.19. 22:11:29
Quote from: Saint
The lead time on the PCB's is around 3 weeks. Plus I have ordered some more GAL's, which are the slowest thing to arrive. The last lot took 40 days!! I ordered them about 7 days ago, so I have a feeling I am going to be waiting for the GAL's to arrive again... :(

Btw, what's about GALs in general? It seems it's harder and harder to get, since GALs are treated as "old technology", everybody suggests use CPLDs instead, but there are few ones which are 5V ones (or at least 5V tolerant I/O) and DIP packaged ... Also sometimes CPLDs feel a bit "too much" for simplier projects ...
Title: Re: Internal memory expansion
Post by: Z80System on 2013.October.19. 22:38:16
Quote
Great! (http://enterpriseforever.com/Smileys/phpbb/smiley.gif) I also saw in the Hungarian thread people talking about memory expansions larger than 512KB. Is this something that people would want? I may be able to get some larger SRAM if there is interest, although it all takes time to get the PCB made, etc.

Hi Saint,

For example, I asked Zozo, why you stopped at 512KB and you did not target 1MB or 2MB ...

I think this internal 512KB expansion is very very cool, probably the coolest hw enhancement since Zozo's IDE controller with what we can use SD cards, already now.

So what can be more cool than this internal 512KB expansion is a 1MB or 2MB internal expansion ... :)

In practice usually we do not use even 512KB memory. Probably that is a hard task to find any application that can use this amount of memory. But the practice is rarely important for me (and probably others) using an EP.

Probably the testing time at boot, and the price can be important too, but the bigger can be better for me. If there is no other disadvantages at the larger expansions. Maybe EXOS cannot handle 2MB of ram, or something like this. Zozo usually knows such things.

Maybe that can be a concern too, that I can wait nearly any time, but maybe that is better, the whole packet not wait for some extra size rams or such, for the other people.

So yes, I would welcome one of my expansions with for example 1 or 2 MB, which can work, but it is not a reqirement at this time.

And an other user thought about his machine, which is a 1MB expanded one, and he asked Zozo whether your expansion will work with that configuration or not. But Zozo said "Some more RAM cannot be wrong ..." :)
Title: Re: Internal memory expansion
Post by: Saint on 2013.October.19. 23:35:22
Btw, what's about GALs in general? It seems it's harder and harder to get, since GALs are treated as "old technology", everybody suggests use CPLDs instead, but there are few ones which are 5V ones (or at least 5V tolerant I/O) and DIP packaged ... Also sometimes CPLDs feel a bit "too much" for simplier projects ...

Yes, sadly I don't think they are manufactured any more. They are certainly marked as discontinued on the Lattice data sheets.

I agree a CPLD seems an overkill in many cases, a GAL is perfect for these old hardware projects, and more than powerful enough.

I think I am going to order quite a few GAL chips from China while I can still get them cheaply - cheaper than I can get a CPLD! I know I will find a use for them all one day... :)
Title: Re: Internal memory expansion
Post by: Saint on 2013.October.19. 23:57:49
So what can be more cool than this internal 512KB expansion is a 1MB or 2MB internal expansion ... :)

Hehe, more is always better! :) I could certainly do a 1mb or 2mb expansion using multiple 512kb SRAM chips and expand the GAL to provide the correct chip enable for each SRAM.

Or you could modify the existing SRAM board by soldering the SRAM directly to the board without a socket (to give extra clearance) and piggy back another SRAM on the top. With a modified GAL you could use another output to provide the chip select for the 2nd SRAM with a piece of wire between the GAL leg and the SRAM chip select leg.

I might give this a go if there is any interest? :D 512KB is enough for me, but I could possibly provide a 1mb board for £20... I'd just need to make sure there is enough clearance in the case.
Title: Re: Internal memory expansion
Post by: lgb on 2013.October.20. 01:07:12
Quote from: Saint
I think I am going to order quite a few GAL chips from China while I can still get them cheaply - cheaper than I can get a CPLD! I know I will find a use for them all one day... :)

Can I ask where (and how) you order those GALs (and maybe the SRAM) exactly? Or is it some kind of "secret source"? :) It seems even more regular parts (like 512K SRAM) is quite hard to find sometimes now, especially in DIP packages. A year ago or so, almost every shops had it (here, in Hungary), now I can feel that it's truely more rare (surely it is not impossible _yet_, but ...) and I guess this tendency will continue, so it's better to switch to new source. Can you suggest something, or do you mean general ebay random searches or so when you wrote "China"? I always afraid of China stuffs, but I have no experience at all in these kind of orders (from abroad of Hungary).
Title: Re: Internal memory expansion
Post by: Zozosoft on 2013.October.20. 01:19:58
Quote from: Saint
Or you could modify the existing SRAM board by soldering the SRAM directly to the board without a socket (to give extra clearance) and piggy back another SRAM on the top. With a modified GAL you could use another output to provide the chip select for the 2nd SRAM with a piece of wire between the GAL leg and the SRAM chip select leg.
Good idea!
Title: Re: Internal memory expansion
Post by: Z80System on 2013.October.20. 01:22:59
Quote
I might give this a go if there is any interest? (http://enterpriseforever.com/Smileys/phpbb/ds_icon_biggrin.gif) 512KB is enough for me, but I could possibly provide a 1mb board for £20... I'd just need to make sure there is enough clearance in the case.


I did not understand the details of the changes exactly,
but if you can build an expansion with 1 mb easily, and there is enough space, and the assembling on the user side is not more complex than the 512KB ones, then the £5 extra price is very good for me.

So in this case one of the "hungarian" boards could be 1MB.
Title: Re: Internal memory expansion
Post by: Saint on 2013.October.20. 14:28:42
Can I ask where (and how) you order those GALs (and maybe the SRAM) exactly? Or is it some kind of "secret source"? :)

I just search eBay for components from international sellers. For GAL's I found these - http://www.ebay.co.uk/itm/10PCS-IC-GAL16V8D-GAL16V8D-25LP-DIP-20-NEW-GOOD-QYALITY-tracking-number-/300920600072?pt=LH_DefaultDomain_0&hash=item461043f608

I've had no problems ordering from overseas sellers so far, other than it can sometimes take a long time to arrive!! :)

I have also been trying surface mount components, but soldering with a soldering iron is very hard for SMD. So I have bought myself a hot air rework station, but it need some practice with solder paste...
Title: Re: Internal memory expansion
Post by: Saint on 2013.October.20. 14:30:13
So in this case one of the "hungarian" boards could be 1MB.

I will try!! :)
Title: Re: Internal memory expansion
Post by: Zozosoft on 2013.October.21. 10:28:53
Update: Current orders from Hungary: 10!
Title: Re: Internal memory expansion
Post by: Saint on 2013.October.21. 23:50:18
Thanks for the update Zozo! :)

I've made up another 4 boards tonight, I'll test them tomorrow and then Bruce and fatbob_gb are next in line, as all the Hungarian orders will go out together when I get the next batch of PCB's.
Title: Re: Internal memory expansion
Post by: Zozosoft on 2013.October.22. 07:25:32
Quote from: Saint
all the Hungarian orders will go out together when I get the next batch of PCB's.
The 1M version can be chosen? It is a +5 GBP?
I will ask which version wanted.
Title: Re: Internal memory expansion
Post by: Saint on 2013.October.22. 10:29:54
Quote from: Zozosoft
The 1M version can be chosen? It is a +5 GBP?
I will ask which version wanted.
Yes, if you would like to find out how many 1MB / 512KB versions people would like, I will try and got those built. I've checked the clearance, and it looks ok to me, so the only thing left to do is to program a different GAL and hook up a bit of wire for the 2nd chip select. And, yes, I can do the 1MB for £20.

My only concern is heat in the bottom SRAM chip as it will have no ventilation with the 2nd SRAM on top of it. The chip will run up to 85 degrees centigrade according to the datasheet, though, so I don't think it should be a problem. The SRAM was only slightly warm in testing.
Title: Re: Internal memory expansion
Post by: lgb on 2013.October.22. 10:39:02
Quote from: Saint
Yes, if you would like to find out how many 1MB / 512KB versions people would like, I will try and got those built. I've checked the clearance, and it looks ok to me, so the only thing left to do is to program a different GAL and hook up a bit of wire for the 2nd chip select. And, yes, I can do the 1MB for £20.

My only concern is heat in the bottom SRAM chip as it will have no ventilation with the 2nd SRAM on top of it. The chip will run up to 85 degrees centigrade according to the datasheet, though, so I don't think it should be a problem. The SRAM was only slightly warm in testing.

I have no idea about the temperature and the datasheet in this case, but maybe - in general - the "worst" temperature is at the boundary of working conditions ie, very rapid r/w access near the max speed of the memory, as the needed curren to supply on Vcc is related to the frequency in general (and temperature is related the current after tall, emitted heat because of the resistance, etc). So if your SRAM is 70ns I doubt it will be near to 85 degrees if the memory accesses in general occurs more rarely than 70ns ... Well, at least if that number of 85 is defined for the maximum temperature at the most "extreme" usage given by the specification.
Title: Re: Internal memory expansion
Post by: Zozosoft on 2013.October.22. 10:42:17
Quote from: Saint

 so I don't think it should be a problem.
Strange example :-) (http://gafz.enterpriseforever.com/Galery/Bovitmenyek/Picture/IM000722.jpg) (Once I found 8x 8K SRAM chips in a old PCB, and built a 64K expansion for my EP :-D )
Title: Re: Internal memory expansion
Post by: Saint on 2013.October.22. 10:48:43
Quote from: lgb
I have no idea about the temperature and the datasheet in this case, but maybe - in general - the "worst" temperature is at the boundary of working conditions ie, very rapid r/w access near the max speed of the memory, as the needed curren to supply on Vcc is related to the frequency in general (and temperature is related the current after tall, emitted heat because of the resistance, etc). So if your SRAM is 70ns I doubt it will be near to 85 degrees if the memory accesses in general occurs more rarely than 70ns ... Well, at least if that number of 85 is defined for the maximum temperature at the most "extreme" usage given by the specification.
Yes, I agree. The SRAM is actually 55ns, so it is running way below it's maximum frequency, and will be drawing more current while switching. So it should be running cool compared to what it can do.

Zozo: Wow, that chip stack is awesome! :D
Title: Re: Internal memory expansion
Post by: Zozosoft on 2013.October.22. 11:01:29
Quote from: Saint
The SRAM is actually 55ns
I hope it is will be enought fast for 10MHz Z80!
Title: Re: Internal memory expansion
Post by: Saint on 2013.October.22. 11:06:28
Quote from: Zozosoft
I hope it is will be enought fast for 10MHz Z80!
Easily, yes. :) 10Mhz is 100ns cycles, so I think you could run over 20Mhz with this SRAM, probably much more given the Z80 memory access cycles.

Are you replacing the internal RAM also? Or is that just slow access anyway as it's through the Nick?
Title: Re: Internal memory expansion
Post by: Zozosoft on 2013.October.22. 11:12:29
Quote from: Saint
Easily, yes. :) 10Mhz is 100ns cycles, so I think you could run over 20Mhz with this SRAM, probably much more given the Z80 memory access cycles.
Great!

Quote
Are you replacing the internal RAM also? Or is that just slow access anyway as it's through the Nick?
Not needed because the CPU access also controled by the Nick, with fixed timing.
I tested with 10Mhz some motherboards, not problem with the video memory. But the old slow DRAM expansions not working at this turbo speed.
Title: Re: Internal memory expansion
Post by: lgb on 2013.October.22. 11:46:31
Quote from: Saint
Yes, I agree. The SRAM is actually 55ns, so it is running way below it's maximum frequency, and will be drawing more current while switching. So it should be running cool compared to what it can do.

Also an important factor: I don't know your design too much, but modern CMOS SRAM memories go into low-power mode if chip select is inactive. Some can create a design that CS (or CE, it seems there are different habits to name this kind of pin on ICs) is always active, tied to GND (since it's a low-active signal) and only OE and WE is used to control RD/WR operations. However in this design causes not allow SRAM to go into low-power mode when it's not needed. A typical value is like 10uA only when not selected, but eg 10mA if it is, and even higher like 50mA or so when an operation is done. At the other hand, I was told many years ago that at quite rapid access it's better idea (even with the cost to increasing heat and current) to keep IC always selected since near its specification, it can be faster to have stable address signals already when OE or WE happens actually. If CE is activated only at the same time, maybe you can't reach the full speed of the memory. However since I guess it's far from its limit, it's better not to hard-wire CS as selected all the time. Sorry if I write too trivial stuffs, honestly I have limited experience, and much more 'by theory' stuff :) Also I don't know your implementation, and the GAL internals how you create SRAM signals after all.
Title: Re: Internal memory expansion
Post by: Zozosoft on 2013.October.22. 22:14:31
Quote from: Saint
Yes, if you would like to find out how many 1MB / 512KB versions people would like, I will try and got those built.
Currently: 7x1M, 3x512K, another one waiting for answer
Title: Re: Internal memory expansion
Post by: Saint on 2013.October.22. 22:50:48
I have written up a simple how-to for installing the RAM expansion!

http://www.retrohq.co.uk/Installation.html (http://www.retrohq.co.uk/Installation.html)

Bagpuss22 has received his today, so I hope we'll have the first upgraded Enterprise soon. :)
Title: Re: Internal memory expansion
Post by: Saint on 2013.October.22. 23:02:20
Quote from: lgb
Also an important factor: I don't know your design too much, but modern CMOS SRAM memories go into low-power mode if chip select is inactive. Some can create a design that CS (or CE, it seems there are different habits to name this kind of pin on ICs) is always active, tied to GND (since it's a low-active signal) and only OE and WE is used to control RD/WR operations. 
In the case of the Alliance SRAM I am using, it has /OE, /WE and /CE. I simply connect /RD to /OE, /WR to /WE and then the address decoding output to /CE. So as long as the memory is not being accessed, the chip is not enabled. If there is any power saving, then the chip will power down properly. :)
Title: Re: Internal memory expansion
Post by: Bagpuss22 on 2013.October.23. 20:11:10
Well I have installed both EXOS 2.4beta AND 512K!!

512K did not register at first, but a wiggle later and all is well...... 
APART from then my original keyboard membrane has now given up!!! (new one ordered :smt023)

(http://s21.postimg.org/hd7mtx7bb/IMG_0365.jpg)
The inner sanctum!



(http://s21.postimg.org/4w0z6rc5j/IMG_0364.jpg)
Loads of memory!!!!

Thank you JAMES! :shock:

BP22
Title: Re: Internal memory expansion
Post by: Z80System on 2013.October.23. 20:28:24
In this photo I can see the sizes better.

It is so tiny, it is so little, it is so cool.

When will the SD card + memory combo be ready ? :)

Is it not possible to work an IDE controller (like Zozo's one)+ IDE to SD + SD card alltogether to a cartridge ? RAM expansion will be in this new form, and SD card goes to a cartridge ?

If it would communicate through IDE, then the softwares nearly ready, because EXOS handles that. As far as I know ...

And in a cartridge, we could replace the SD card, when it has no wifi. We will not place the only screw to the cartridge, and we can split the cartridge easily to replace the SD card.
Title: Re: Internal memory expansion
Post by: Saint on 2013.October.23. 23:15:29
Superb! Great to see it working outside of my Enterprise. :ds_icon_cheesygrin: Odd you should have connection problems, though -- I've not had even one problem throughout testing the units, they have all just worked perfectly first time!

The keyboard membranes are a nightmare. I unplug and replug mine so regularly, it's going to stop working soon... :shock:

Z80System:
Yes, it is a very tiny PCB! I had to rework the PCB layout a couple of times to get it so small, and it halved the price of the PCB manufacture getting it down under 5x5cm.

I have plans to 3D print a new cartridge for the SD card interface with a slot in the end for removing the SD card, or failing that I have some edge connectors for an expansion port version. I have had quotes already for the 3D printing, and it doesn't seem impossible. But equally I have ideas to make an internal SD card + memory expansion, just because I think it would be cool to have an internal "hard drive" in the Enterprise... :ds_icon_cheesygrin: It would replace the existing memory expansion with the same connectors.

And a quick update: I have received my new order of SRAM chips today and have written new GAL logic for the 1MB expansion board, so I will try the 1MB board next.
Title: Re: Internal memory expansion
Post by: Bagpuss22 on 2013.October.24. 10:12:28
@Saint

The new keyboard membranes are VERY good quality, and are much better than the originals.

They are made of slightly thicker plastic and so will last longer.  I have upgraded both my machines
now and even sent some to Zozo.

Russ
Title: Re: Internal memory expansion
Post by: Saint on 2013.October.24. 10:27:04
Quote from: Bagpuss22
@Saint

The new keyboard membranes are VERY good quality, and are much better than the originals.

They are made of slightly thicker plastic and so will last longer.  I have upgraded both my machines
now and even sent some to Zozo.

Russ
I've been thinking about getting some, for when mine do eventually die! I will probably take the plunge with the bit of cash I'm getting from the RAM expansions... only seems right. :razz:

Good to hear they are nice quality!
Title: Re: Internal memory expansion
Post by: Z80System on 2013.October.24. 11:29:40
Quote
But equally I have ideas to make an internal SD card + memory expansion, just because I think it would be cool to have an internal "hard drive" in the Enterprise... (http://enterpriseforever.com/Smileys/phpbb/ds_icon_cheesygrin.gif) It would replace the existing memory expansion with the same connectors.

Yes, it is a very very cool idea too ... and with those wifi SD cards, the main problem is solved (accessing the SD from outside of the EP), even if there will not be other EP supported way to access it.

So I think everyone just cannot wait for it ... :)
Title: Re: Internal memory expansion
Post by: Saint on 2013.October.24. 22:10:46
Zozo: I've tried the 1MB expansion, and have a working prototype, but it takes me too long to solder on the piggyback chip. It's quite awkward as my hands are not very steady, and the result is quite messy. So I'm afraid I will only be offering the 512KB expansion for the moment. :(

So if you could check for me how many 512KB expansions are wanted from Hungary, I'll build up the remaining boards I have for 512KB.

Once I've done the SD card interface I may look at making a "mega" memory expansion which will accept up to 4MB (8 chips) and decode everything but the cartridge and EXOS memory pages if enough people are interested! It would use the same connectors, and you could also re-use the socketed SRAM from the 512KB board.
Title: Re: Internal memory expansion
Post by: Zozosoft on 2013.October.24. 22:22:48
Send the components and I will assemble it!
Title: Re: Internal memory expansion
Post by: fatbob_gb on 2013.October.24. 22:41:40
My newly installed memory expansion (and EXOS 2.4beta) is working perfectly :ds_icon_cheesygrin:

Sadly another Enterprise membrane gave up the ghost though, luckily I had a spare one handy, better get another one ordered.

Thanks James & Zozosoft also for the updated EXOS.
Title: Re: Internal memory expansion
Post by: Saint on 2013.October.24. 22:46:49
Quote from: Zozosoft
Send the components and I will assemble it!
I could send you kit form if you wish! It's a simple modification -- just requires the 1MB GAL, one trace to be cut, a wire to be run from a pad underneath the board to the SRAM CE and a capacitor between GND and VCC on the top SRAM. I've attached a picture of my 1MB expansion.

I'll let you know when all the bits arrive and when I'm ready to ship! :ds_icon_cheesygrin:
Title: Re: Internal memory expansion
Post by: Saint on 2013.October.24. 22:49:07
Quote from: fatbob_gb
My newly installed memory expansion (and EXOS 2.4beta) is working perfectly:ds_icon_cheesygrin:

Sadly another Enterprise membrane gave up the ghost though, luckily I had a spare one handy, better get another one ordered.

Thanks James & Zozosoft also for the updated EXOS.
Great stuff! Glad to hear another is working... :smt041

Taking the Enterprise apart is always a bit of a risk with the keyboard membrane -- do you not have enough length left to cut the end off? I've done that far too many times now... :roll:
Title: Re: Internal memory expansion
Post by: fatbob_gb on 2013.October.25. 00:10:18
Quote from: Saint
Great stuff! Glad to hear another is working... :smt041

Taking the Enterprise apart is always a bit of a risk with the keyboard membrane -- do you not have enough length left to cut the end off? I've done that far too many times now... :roll:
Last time I opened it I had to cut the ends off and only just managed to get it back together so I ordered a spare membrane just in case.  When I opened it up tonight what was left of the membrane was so brittle that there was very little that I could do with it. Hopefully the new one will last me for a few years yet, I will still order a spare though.
Title: Re: Internal memory expansion
Post by: lgb on 2013.October.25. 09:00:54
Quote from: Saint
Zozo: I've tried the 1MB expansion, and have a working prototype, but it takes me too long to solder on the piggyback chip. It's quite awkward as my hands are not very steady, and the result is quite messy. So I'm afraid I will only be offering the 512KB expansion for the moment. :(
Can it be the option to have all GALs (even the "512K only" versions) programmed for 1M (just one output is simply not used with the 512K version), and buyer can ask for +1 SRAM IC, but its his responsibility to solder the extra SRAM chip piggy-back on the other one and the extra wire from the GAL to the CE line of the new the SRAM IC?
Title: Re: Internal memory expansion
Post by: Zozosoft on 2013.October.25. 13:22:45
For the piggy back the best way solder the chips before place to the PCB.
Title: Re: Internal memory expansion
Post by: Saint on 2013.October.25. 19:53:50
I've had another go at doing the 1MB board and this time did a nice job if it, and did it quite quickly, so I'll build up and test all the 1MB boards here after all! :)

Using some liquid flux on the chip legs really helped get the solder flowing nicely.
Title: Re: Internal memory expansion
Post by: Zozosoft on 2013.October.27. 22:17:56
Currently: 8x1M, 4x512K, another one waiting for answer.

Do you want some money prepaid? (For buying components.)
Title: Re: Internal memory expansion
Post by: Saint on 2013.October.28. 09:44:32
Quote from: Zozosoft
Currently: 8x1M, 4x512K, another one waiting for answer.

Do you want some money prepaid? (For buying components.)
Thanks for offer, I think I'll be OK! I placed quite a large order for SRAM last week, which should cover most of the units, so I'm just waiting on the PCB's and GAL's now to build up the remaining units.

Thanks!
Title: Re: Internal memory expansion
Post by: geo1977 on 2013.November.04. 09:22:48
Today im very happy my precious Enterprise have 589kb memmory and working without problem :ds_icon_cheesygrin:
THANKS !!!!!!!! JAMES!!!!!!!
Title: Re: Internal memory expansion
Post by: Saint on 2013.November.04. 10:08:21
Quote from: geo1977
Today im very happy my precious Enterprise have 589kb memmory and working without problem :ds_icon_cheesygrin:
THANKS !!!!!!!! JAMES!!!!!!!
Great stuff! :mrgreen:
Title: Re: Internal memory expansion
Post by: Zozosoft on 2013.November.05. 07:19:07
Currently for Hungary: 8x1M, 5x512K
Title: Re: Internal memory expansion
Post by: Saint on 2013.November.05. 10:17:08
Quote from: Zozosoft
Currently for Hungary: 8x1M, 5x512K
Thanks for the update, I have 1x512K and 3x1MB built up ready and the next batch of boards should arrive soon -- they were shipped on the 28/10. I'll get those built up when the boards arrive, then it's just a matter of when the GAL's arrive!!
Title: Re: Internal memory expansion
Post by: Zozosoft on 2013.November.23. 16:55:54
Is there any news? :oops:
Title: Re: Internal memory expansion
Post by: Saint on 2013.November.23. 18:34:03
Still waiting for pcb's and GAL's... :(
Title: Re: Internal memory expansion
Post by: Saint on 2013.December.05. 11:46:33
PCB's have arrived!! I'll start building them up tonight. Still waiting for the GAL's, but at least I can make up the rest of the boards now. Putting the GALs in is a really quick job. :ds_icon_cheesygrin:
Title: Re: Internal memory expansion
Post by: Zozosoft on 2013.December.05. 12:04:07
Great news! :ds_icon_cheesygrin:
Title: Re: Internal memory expansion
Post by: Saint on 2013.December.09. 23:28:53
Update:

6x1MB units built -- 4 tested OK, waiting for GAL's to test the others.
5x512KB units built -- waiting for GAL's to test.

I'll build up the last 2x1MB units in the next day or so, then we're just waiting on the GAL's!
Title: Re: Internal memory expansion
Post by: Saint on 2014.January.03. 09:47:25
Another update... but not a very interesting one! Still waiting for the GALs, I've ordered some more from somewhere else in the hope at least one lot will arrive in the next few weeks!! Very frustrating... I think I'll have to use in-production IC's in the future... :)
Title: Re: Internal memory expansion
Post by: Ep128 on 2014.January.26. 00:17:13
Quote from: Saint
Still waiting for pcb's and GAL's... :(
Change possibly...? We may live in hopes? :-)
Title: Re: Internal memory expansion
Post by: Saint on 2014.January.26. 00:31:31
Still waiting! I expect to have them in the next 2-4 weeks. I will not be using obsolete parts again in the future... has been a complete pain! :)

I've certainly not forgotten about the Enterprise hardware projects, just a frustratingly long wait for components I'm afraid. :(

I've been practicing with the hot air gun and have found a place you can get cheap Mylar paste stencils made up, so I'm getting ready for doing surface mount work. May even build myself a reflow oven and do it properly... :D
Title: Re: Internal memory expansion
Post by: Saint on 2014.January.31. 23:56:29
I have 20 GALs now. I will get on and finish the boards in the coming days... :D
Title: Re: Internal memory expansion
Post by: Ep128 on 2014.February.01. 00:43:44
Quote from: Saint
I have 20 GALs now. I will get on and finish the boards in the coming days... :D
Yeeeeaaah! :-)
Title: Re: Internal memory expansion
Post by: Zozosoft on 2014.February.01. 00:47:33
Great news!!! :ds_icon_cheesygrin: :ds_icon_cheesygrin: :ds_icon_cheesygrin:

Unfortunately the HUF got a very bad exchange rates at current days :evil: :cry: :(
Title: Re: Internal memory expansion
Post by: Saint on 2014.February.01. 08:44:58

Unfortunately the HUF got a very bad exchange rates at current days :evil: :cry: :(

Oh that is annoying. I had noticed the pound was quite strong at the moment against the dollar. Good for us, not good for you. :(
Title: Re: Internal memory expansion
Post by: Saint on 2014.February.05. 22:47:54
Another 2x1MB finished and tested. Remaining 4x512KB finished, waiting for more SRAM (here in a couple of days).

So total ready to ship currently:

1x512KB
6x1MB

The rest I hope to finish this weekend and be ready to post next week! :ds_icon_cheesygrin:

Finally...
Title: Re: Internal memory expansion
Post by: Ep128 on 2014.February.06. 00:01:41
Quote from: Saint
Another 2x1MB finished and tested. Remaining 4x512KB finished, waiting for more SRAM (here in a couple of days).

So total ready to ship currently:

1x512KB
6x1MB

The rest I hope to finish this weekend and be ready to post next week! :ds_icon_cheesygrin:

Finally...
Thx! :-) Great! :smt041
Title: Re: Internal memory expansion
Post by: Zozosoft on 2014.February.06. 10:13:08
Quote from: Saint
The rest I hope to finish this weekend and be ready to post next week! :ds_icon_cheesygrin:
Great! I am looking forward to getting it :-D 10Mhz Z80 needs a fast memory :-)
Title: Re: Internal memory expansion
Post by: Z80System on 2014.February.06. 10:17:03
And will you kill all of the original rams from the 10MHz configuration ? Or do you have to kill only the f8-fb modules ?
Title: Re: Internal memory expansion
Post by: Zozosoft on 2014.February.06. 10:58:30
Quote from: Z80System
And will you kill all of the original rams from the 10MHz configuration ? Or do you have to kill only the f8-fb modules ?
Onboard 64K (video) RAM used as original, because the Nick control the access timing. Only the internal expansion 64K needed to be replaced.
Title: Re: Internal memory expansion
Post by: Saint on 2014.February.07. 22:26:00
All boards built and tested (8x1MB, 5x512KB)! I just need to sort out the connector blocks (they need to be cut to size) and then it's all ready to ship. I'll check the weight and figure out the postage in the next day or so and I'll drop you a message on the final price, Zozo.

Shipping should only take a few days, so you could well have these by the end of next week. :ds_icon_cheesygrin:
Title: Re: Internal memory expansion
Post by: Zozosoft on 2014.February.10. 09:45:50
Quote from: Saint
I'll check the weight and figure out the postage in the next day or so and I'll drop you a message on the final price, Zozo.
Have you calculated the final price?
Title: Re: Internal memory expansion
Post by: Saint on 2014.February.10. 10:22:28
Yes, I got carried away looking at EXDOS last night and forgot to post. :oops: 

I'll drop you a PM with the details.
Title: Re: Internal memory expansion
Post by: Saint on 2014.February.10. 14:23:30
Boxed and ready... :)
Title: Re: Internal memory expansion
Post by: Zozosoft on 2014.February.10. 14:28:10
Quote from: Saint
Boxed and ready... :)
Great! :ds_icon_cheesygrin:
Title: Re: Internal memory expansion
Post by: Saint on 2014.February.10. 21:16:29
Posted this evening, let me know when they arrive! Glad to have them on the way at last. :)
Title: Re: Internal memory expansion
Post by: Zozosoft on 2014.February.13. 20:02:28
Can you write Ebay links for connecting components?

I got some special requests, for example replace old 256K expansion with the new 1M, but the old 256K will go for another machine.
Then I think the most easy way if I have some extra connection kits because I'm not sure the old connecting cables survive the removal :oops:
Title: Re: Internal memory expansion
Post by: Z80System on 2014.February.14. 11:25:49
Yeah, Zozo, I wanted to ask you too, testing the assembly, and/or putting some pictures of the assembly to the forum, not only the final result, but the steps, or things require attention, if there are any ...

I will assembly my expansions much later on, but that could be cool, I would know what I will do, by then.

(I'm almost sure, that these sentences have more language errors than the bugs in EXOS ... :))
Title: Re: Internal memory expansion
Post by: Saint on 2014.February.15. 11:24:30
I wrote up some instructions here...

http://www.retrohq.co.uk/Installation.html

:D
Title: Re: Internal memory expansion
Post by: Saint on 2014.February.16. 09:55:05
Can you write Ebay links for connecting components?

I got some special requests, for example replace old 256K expansion with the new 1M, but the old 256K will go for another machine.
Then I think the most easy way if I have some extra connection kits because I'm not sure the old connecting cables survive the removal :oops:

Sorry, didn't see your question before! Do you mean male and female headers, or the 10 way ribbon connectors as well?
Title: Re: Internal memory expansion
Post by: Zozosoft on 2014.February.16. 09:57:50
Quote from: Saint
 Do you mean male and female headers, or the 10 way ribbon connectors as well?
Both. All components which used for connect the main and expansion board.
Title: Re: Internal memory expansion
Post by: Saint on 2014.February.16. 12:13:23
Male Headers (http://www.ebay.co.uk/itm/10pcs-40-Pin-1x40-2-54-breakable-pin-header-Single-Row-Male-Female-Header-Strip-/321221867172?pt=UK_BOI_Electrical_Components_Supplies_ET&hash=item4aca50b6a4)
Right Angle Male Header (http://www.ebay.co.uk/itm/40-WAY-RIGHT-ANGLE-HEADER-CONNECTOR-0-1-inch-/121274863093?pt=UK_BOI_Electrical_Components_Supplies_ET&hash=item1c3c8b8df5)
Female Headers (http://www.ebay.co.uk/itm/10pcs-2-54mm-Double-Row-Female-Straight-Header-Socket-Pin-Strip-Connector-/350804828041?pt=UK_BOI_Electrical_Components_Supplies_ET&var=&hash=item51ad98df89)
10p DuPont Connector (http://www.ebay.co.uk/itm/New-8-PCS-30cm-Dupont-Wire-Cable-Line-Female-to-Female-10P-10P-2-54mm-Jumper-C14-/261182041659?pt=UK_BOI_Electrical_Components_Supplies_ET&hash=item3ccfa9ae3b)

The DuPont connector was the supplier I ordered from, the headers I would have just ordered the cheapest I could find. May have been UK or China, I don't remember, and it's gone from by ebay history! Hope this is useful... :)
Title: Re: Internal memory expansion
Post by: Zozosoft on 2014.February.16. 19:06:51
Quote from: Saint
 Hope this is useful... :)
Thanks!
Title: Re: Internal memory expansion
Post by: Zozosoft on 2014.February.18. 12:32:47
Quote from: Saint
Boxed and ready... :)
Arrived! :ds_icon_cheesygrin:
Title: Re: Internal memory expansion
Post by: Saint on 2014.February.18. 12:54:55
Quote from: Zozosoft
Arrived! :ds_icon_cheesygrin:
Fantastic! I look forward to seeing the new super-fast Enterprise computers which come out of this. May even over-clock one myself... :mrgreen:

They're all marked up 512K or 1MB on the anti-static bags. Although it's very easy to tell the 1MB units... :razz:
Title: Re: Internal memory expansion
Post by: Zozosoft on 2014.February.18. 23:09:11
First one installed to Szalai56 machine :ds_icon_cheesygrin:
Title: Re: Internal memory expansion
Post by: Saint on 2014.February.19. 10:02:31
Quote from: Zozosoft
First one installed to Szalai56 machine :ds_icon_cheesygrin:
Awesome! Great to see my little boards getting fitted... :ds_icon_cheesygrin:
Title: Re: Internal memory expansion
Post by: Zozosoft on 2014.February.25. 00:22:59
Next:1M added to my machine :-D
Not too easy, because this machine has a lot of hacks :oops: : 6Mhz SMD Turbo Card, 7.12 Mhz turbo, switchable color/mono composite video, internal speaker mute switch, external keyboard connector for rewired PC keyboard (20 years ago there was no new membrane :-( currently installed brand new from RWAP :-) ) Miles of wires :lol:
And now adding 10Mhz turbo :-D
Title: Re: Internal memory expansion
Post by: Saint on 2014.February.25. 10:19:12
10Mhz 1.0625MB Enterprise. Very nice. :ds_icon_cheesygrin:

You must tell us how to modify the Enterprise for 10Mhz, as I feel I might have to do this for my Arabic Enterprise once I'm happy it's all working properly (replacing all the caps at the moment!).
Title: Re: Internal memory expansion
Post by: Z80System on 2014.February.25. 10:29:09
If a game would load all of the one megabyte,

for what time would it load ?
Title: Re: Internal memory expansion
Post by: Saint on 2014.February.25. 10:38:01
Quote from: Z80System
If a game would load all of the one megabyte,

for what time would it load ?
It wont affect floppy load time (so it's still a long time!), but with an SD / CF interface, it should only take perhaps 2-3 seconds.
Title: Re: Internal memory expansion
Post by: Zozosoft on 2014.February.25. 10:59:58
Quote from: Saint
You must tell us how to modify the Enterprise for 10Mhz, as I feel I might have to do this for my Arabic Enterprise once I'm happy it's all working properly (replacing all the caps at the moment!).
Ok I will start overclocking topic :-)
Title: Re: Internal memory expansion
Post by: szipucsu on 2014.February.25. 13:05:54
Quote from: Z80System
If a game would load all of the one megabyte,

for what time would it load ?
Using tape it would take ages. :D
About one or two hours I think. You would be very sad if you accidentally pressed reset after an hour or the loading stopped with a cassette CRC error right before the end of loading. :D
Title: Re: Internal memory expansion
Post by: geco on 2014.February.25. 13:20:27
3840 seconds at 2400 baud, calculated with approx 1.5 second breaks between two 4Kb blocks :D
It would take only 64 minutes, only some coffee breaks :D
Title: Re: Internal memory expansion
Post by: Z80System on 2014.February.25. 13:33:02
I thought of a floppy or HDD scenario. A normal game can take 5-15 seconds from floppy/HDD, then a 1MB game probably can take a minute, cannot it ?

The new SD solution is not a reality just now, and the current solution is limited to Z80 speed. (Ooooops, Does the 10MHz Z80 load 2.5 times faster than the original ? :))
Title: Re: Internal memory expansion
Post by: Zozosoft on 2014.February.27. 00:07:27
Now I'm running the Small Demo for least two hours at my 10MHz machine, with the 1MB expansion. And it is looks stable :ds_icon_cheesygrin: previously only tested with little BASIC programs.

The digi sound samples are very funny when played at 10MHz :-) Dave generated musics still music because the player program synchronized with the 50Hz video IRQ, just playing in higher octave :lol:
Title: Re: Internal memory expansion
Post by: Z80System on 2014.February.27. 09:22:27
Quote
just playing in higher octave (http://enterpriseforever.com/Smileys/phpbb/ds_icon_lol.gif)

How can the 10MHz Z80 clock influent the dave frequencies ? Is there a hardware incompatibility betwen the DAVE and 10MHz solution ?
Title: Re: Internal memory expansion
Post by: Zozosoft on 2014.February.27. 09:36:20
Quote from: Z80System
How can the 10MHz Z80 clock influent the dave frequencies ? Is there a hardware incompatibility betwen the DAVE and 10MHz solution ?
Dave always running on System Clock (2xZ80 speed), if you raise the system speed then Dave also running faster, sound frequencies will be higher.
For the 6MHz machine (12MHz System Clock) can be adjusted the Dave on the port 191 (BFh), then it is can generate same sound frequencies as the original 4MHz (8MHz System Clock) machines.

But in the future programs this is can be handled by software, just need recalculate which sound frequencies sent to Dave.
Title: Re: Internal memory expansion
Post by: Z80System on 2014.February.27. 09:44:43
Quote
But in the future programs this is can be handled by software, just need recalculate which sound frequencies sent to Dave.
I think the future programs are not the problem. The existing programs are the problem ...

At 10MHz probably many program will be better playable simply because of the speed ... 3D programs and such ... any program that was slow on 4 MHz ... but the sound will be almost broken ...
Title: Re: Internal memory expansion
Post by: Zozosoft on 2014.February.27. 09:56:17
Quote from: Z80System
but the sound will be almost broken ...
Not broken just different. Sometimes very funny :-) You can easy try it in a emulator.
Title: Re: Internal memory expansion
Post by: jltursan on 2014.February.28. 19:36:07
Maybe 10Mhz could help the machine to emulate other architectures like MSX. CPC & Spectrum soft are in some way very close to EP; but being pattern based instead bitmapped makes MSX video is a bit different.
Title: Re: Internal memory expansion
Post by: geco on 2014.March.03. 09:54:10
Quote from: jltursan
Maybe 10Mhz could help the machine to emulate other architectures like MSX. CPC & Spectrum soft are in some way very close to EP; but being pattern based instead bitmapped makes MSX video is a bit different.
I think even 10 MHz would not be enough for converting the graphics for a software emulator (full screen converting), it could be enough for a hardware emulator for those games where the whole screen does not change, or we can leave the screen as it is, and probably 4 MHz is enough for Speccy and CPC ;)
Title: Re: Internal memory expansion
Post by: Zozosoft on 2014.March.17. 22:58:11
Currently the last 64K which are originaly at FC-FFh, now at BC-BFh (1M expansion). Can you make modified GAL program where these at 7C-7Fh?
For compatibility with expanded MICROTEAM card, where 10-5Fh,90-BFh are allocated?

I have a GAL capable programmer, existing GAL ICs can be reprogrammed?
Title: Re: Internal memory expansion
Post by: Saint on 2014.March.18. 10:19:58
Quote from: Zozosoft
Currently the last 64K which are originaly at FC-FFh, now at BC-BFh (1M expansion). Can you make modified GAL program where these at 7C-7Fh?
For compatibility with expanded MICROTEAM card, where 10-5Fh,90-BFh are allocated?

I have a GAL capable programmer, existing GAL ICs can be reprogrammed?
Yes, sure, I can make a modified GAL program. It will be easier to remap the whole of the 2nd 512KB, how about I move it to 60-7F? (program attached to do this)

If you want to make modifications and compile your own, get WinCupl and compile the PLD file for the GAL16V8 and then program the JED file it outputs. There's no problem reprogramming a GAL.
Title: Re: Internal memory expansion
Post by: Zozosoft on 2014.March.18. 10:26:15
Quote from: Saint
Yes, sure, I can make a modified GAL program. It will be easier to remap the whole of the 2nd 512KB, how about I move it to 60-7F? (program attached to do this)
It is ok! Thanks! I will try it :-)
Title: Re: Internal memory expansion
Post by: Zozosoft on 2014.March.18. 23:55:47
Working :ds_icon_cheesygrin:
I got some unexpected problem with the modified MICROTEAM card: the DRAM address are also expanded to C0-DFh, this is internaly disabled for avoid the mirrored segments, but the card 245 bus driver IC also drived the data bus at this area. Then 64K from the internal expansion are missing at DC-DFh.
Now I added one AND gate which are combine the A21 and A20 lines, then the card fully disabled at C0+ area.

Now Ep1218's machine have total 2624K RAM: 64K onboard, 1024K at internal expansion, 1024K SRAM and 512K DRAM at modified MICROTEAM card.
And 64K onboard, 64K cartridge and 512K Flash ROM on the card, =640K ROM
Total 3264K used of the 4096K address space :-)
Title: Re: Internal memory expansion
Post by: Z80System on 2014.March.19. 00:01:22
Quote
Total 3264K used of the 4096K address space (http://enterpriseforever.com/Smileys/phpbb/ds_icon_smile.gif)
Fck yeah ! :)
Title: Re: Internal memory expansion
Post by: Ep128 on 2014.March.19. 00:57:32
Thanks for the modified GAL program! :smt041  Unbelievable, wonderful... :)
Title: Re: Internal memory expansion
Post by: gflorez on 2014.March.19. 08:29:56
Zozo says he has re-modified further his Microteam, not the gal....

I think the emulator now needs to be adapted to 640k of posible ROM.
Title: Re: Internal memory expansion
Post by: Zozosoft on 2014.March.19. 08:36:22
Quote from: gflorez
Zozo says he has re-modified further his Microteam, not the gal....
The new GAL program also needed!

Quote
I think the emulator now needs to be adapted to 640k of posible ROM.
It is can be done by epmemcfg.exe.
Title: Re: Internal memory expansion
Post by: Saint on 2014.March.19. 10:05:36
Wow, very cool! :)
Title: Re: Internal memory expansion
Post by: gflorez on 2014.March.19. 10:25:04
Sorry, I've underestimated you Zozo... Great! I want the same EP thing....



By the way, where I can find that epmemcfg.exe program?. I have looking the ep128emu installation, this page and the WEB, but I've only found references to it.
Title: Re: Internal memory expansion
Post by: Zozosoft on 2014.March.19. 10:40:41
Quote from: gflorez
I want the same EP thing....
Will you buy a 1M expansion from Saint? Ask it with the modified GAL program, and I will add the extra AND gate to your card for the proper address decoding.

Quote
By the way, where I can find that epmemcfg.exe program?. I have looking the ep128emu installation, this page and the WEB, but I've only found references to it.
There is it. (http://enterpriseforever.com/programozas/exdos-283/?action=dlattach;attach=2382)
You define the RAM and ROM segments in the config file, and this program will compile it to an ep128emu snapshot file.
Title: Re: Internal memory expansion
Post by: gflorez on 2014.March.19. 12:12:47
No, I don't have Saint's expansion.... still. It's only a joke, I have yet (actually very near Hungary...) an excess of RAM for a normal use, and almost as ROM space as you. Step by step.

Thanks for the link. Is "uncomfortable" not being able to accommodate in the emulator all the roms that you've burned for me...

As having many pairs of shoes and can't place them exposed "suitably" inside a small wardrobe....
Title: Re: Internal memory expansion
Post by: gflorez on 2014.March.19. 12:22:14
A small nuisance: now I don't know where I have allocated the  segments of Ram and Rom in my EP...
Title: Re: Internal memory expansion
Post by: Zozosoft on 2014.March.19. 12:31:01
Quote from: gflorez
A small nuisance: now I don't know where I have allocated the  segments of Ram and Rom in my EP...
00-03 Onboard EXOS ROM
04-07 Cartridge
10-1F,90-9F left SRAM chip on the MICROTEAM card
20-2F,A0-AF Flash ROM chip on the MICROTEAM card
30-3F,B0-BF right SRAM chip on the MICROTEAM card
40-4F,50-5F two row of DRAM chips on the MICROTEAM card
F8-FB internal 64K expansion
FC-FF onboard 64K RAM (video memory)
Title: Re: Internal memory expansion
Post by: Zozosoft on 2014.March.26. 15:42:04
Quote from: Saint
The DuPont connector was the supplier I ordered from,
After 1 month wait I got the DuPont cables. Others got from local store :-)
Title: Re: Internal memory expansion
Post by: Saint on 2014.March.27. 23:11:01
I've ordered another 10 PCB's for the memory expansion if anyone wants any more... :)

There's one to be built for fatbob_gb (I'll do you a 1MB version with my new rev2 PCB -- makes it slightly easier to add the CS line for the 2nd chip).
Title: Re: Internal memory expansion
Post by: gflorez on 2014.June.15. 00:58:42
This (http://www.ebay.es/itm/Enterprise-64-128-512KB-Internal-RAM-Expansion-/141318155427?pt=UK_VintageComputing_RL&hash=item20e737eca3) is Saint selling his superb memory expansion on ebay.

May be I buy him one..... or two....
Title: Re: Internal memory expansion
Post by: Saint on 2014.June.15. 09:08:38
If anyone wants any more let me know, I'm going to make some more soon. Same price as before. :)

Trying to get a bit more cash in for further development... :D
Title: Re: Internal memory expansion
Post by: Zozosoft on 2014.June.16. 09:38:06
1MB version also available?
Title: Re: Internal memory expansion
Post by: Saint on 2014.June.16. 10:21:30
Quote from: Zozosoft
1MB version also available?
Yes, the new PCB's make it a bit easier to do the 1MB board as well.
Title: Re: Internal memory expansion
Post by: gflorez on 2014.June.16. 10:45:23
1MB internal is an abuse.....
Title: Re: Internal memory expansion
Post by: Z80System on 2014.September.18. 13:54:50
Hmmm ... Is not the ebay link of saint's internal memory expansion available anymore ?
Title: Re: Internal memory expansion
Post by: gflorez on 2014.September.18. 15:07:51
Put a private message.
Title: Re: Internal memory expansion
Post by: Z80System on 2014.September.18. 15:10:40
I have my extensions, I just wanted to show the ebay link to somebody ...
Title: Re: Internal memory expansion
Post by: Saint on 2014.September.18. 15:15:43
It looks like it has expired -- you can still get the installation instructions (http://www.retrohq.co.uk/Installation.html) though, if that's of interest.
Title: Re: Internal memory expansion
Post by: Z80System on 2014.September.18. 15:35:02
No, I just wanted to give him a link: "you can buy here if you want it".
Title: Re: Internal memory expansion
Post by: dmacoco on 2014.December.26. 15:53:50
Hello,

Seems to be a little bit late but i wanted to increase the memory of my 64 because it's too much constraint by the limitation of the memory since i've put a sd card.

Is there is some solutions to do it easily now ?
Title: Re: Internal memory expansion
Post by: geco on 2014.December.28. 09:40:35
Hello,

Seems to be a little bit late but i wanted to increase the memory of my 64 because it's too much constraint by the limitation of the memory since i've put a sd card.

Is there is some solutions to do it easily now ?
Hello.
If you do not want to assemble one, then please contact Saint in the forum, or check an EXDOS card with memory expansion on e-Bay, I think this is ultra rare, and if you get one a lot of old softwares will not run, because they use fix memory segments (F8-FB), which will not be available on your machine if you buy an old memory expansion, if I know well Saint's memory expansion contains F8-FB memory segments also.
Title: Re: Internal memory expansion
Post by: Jungsi on 2015.February.09. 17:57:14
I've the memory expansion from Saint and I had a look to add this to my Enterprise 128 but
I'am not good at doing such things like soldering (and this time also unsoldering the mounted
64K expansion) :-)
Is there someone out there who would do this job for me? I'am from Germany - sure I would
pay for your time and the shipping!
Just write me a P.N. if there is someone out there ;-)
Title: Re: Internal memory expansion
Post by: Zozosoft on 2015.February.09. 18:40:07
It is no problem for me :-)
[attach=1][attach=2]
[attach=3][attach=4]
[attach=5][attach=6]
[attach=7][attach=8]
Title: Re: Internal memory expansion
Post by: Jungsi on 2015.February.09. 19:44:23
Nice pictures - it's looking easy when you know what you are doing :-)
Title: Re: Internal memory expansion
Post by: Zozosoft on 2015.February.16. 22:43:01
Is there someone out there who would do this job for me?
Done :ds_icon_cheesygrin:
[attach=1]

Now testing with SymbOS.
Title: Re: Internal memory expansion
Post by: Jungsi on 2015.February.17. 07:10:11
That's great :-)
Title: Re: Internal memory expansion
Post by: Bagpuss22 on 2015.February.18. 14:19:33
Looks great!

Is it better to have a 1Mbyte with SYMBOS?

Do you require mouse?  If so then that's what I need
to get next..

Russ
Title: Re: Internal memory expansion
Post by: gflorez on 2015.February.18. 15:45:21
The required memory for SymbOs begins at 128k, but some utilities can refuse to work. The max can manage is 1M.

You can use the internal joystick or...... build yourself a Boxsoft (http://enterpriseforever.com/egyeb-temak/paintbox-mouse-xr/?action=dlattach;attach=8032;image) interface(Tim Box says he only sold 100...).

Then you must find a Neos mouse on Ebay.

Soon we will have the option to use a PS2 mouse...
Title: Re: Internal memory expansion
Post by: sir_beaker on 2015.May.11. 10:34:10
Hi Saint,

I've sent you a PM about buying one of your lovely internal memory expansions if you have any left? :)
Title: Re: Internal memory expansion
Post by: slugman on 2015.July.10. 12:42:24
Hello Saint,

Just send you also a PM to see if it's still possible to acquire one Expansion Card.

I just fixed my Enterprise 64 (https://enterpriseforever.com/hardware/enterprise-64-video-issue/) and willing to expand his memory in order to be better confortable with the RAM and with the plan to add a SD Interface

Thanks!
Title: Re: Internal memory expansion
Post by: slugman on 2015.July.17. 17:56:25
Is anyone have an email where Saint can be contacted ? I tried to PM him but seems he didn't visit the forum for several weeks. if someone can PM me his email it will be great.

Thanks
Title: Re: Internal memory expansion
Post by: gflorez on 2015.July.17. 22:37:58
He's probably busy.

Be patient, he always answers a PM.

On the other side, a received PM triggers automatically a message to the real email address you put in your profile.
Title: Re: Internal memory expansion
Post by: Zozosoft on 2015.July.18. 09:00:29
a received PM triggers automatically a message to the real email address you put in your profile.
Just if he didn't disable this function.
Title: Re: Internal memory expansion
Post by: slugman on 2015.July.22. 17:29:40
Ok thanks, I'll wait for Saint reply.
Title: Re: Internal memory expansion
Post by: Tutus on 2015.July.28. 11:20:38
Saint disappeared ... :(
Title: Re: Internal memory expansion
Post by: dmacoco on 2015.October.11. 17:57:44
Hello,

I've pm Saint several months ago for an expansion.
He has done a lot of things for enterprise community.

I hope than somebody else will know how to make a ram expansion for my small 64.

Title: Re: Internal memory expansion
Post by: slugman on 2015.October.11. 19:37:47
I tried also to contact Saints without sucess :cry: If someone know another way to get an expansion kit... or if there are any plan for an external version ?
Title: Re: Internal memory expansion
Post by: Tutus on 2015.October.12. 22:23:34
I tried also to contact Saints without sucess :cry: If someone know another way to get an expansion kit... or if there are any plan for an external version ?


I wrote the hungarian forum: if somebody architect, then I produce 20 piece of this. :)
Title: Re: Internal memory expansion
Post by: zzarko on 2015.October.29. 18:14:06
If anyone is making another batch of memory expansions, I'm also interested.
Title: Re: Internal memory expansion
Post by: keyboardjunkie on 2015.October.31. 18:21:46
I live in the UK and would be interested in 2 of these memory expansions - can someone let me know if there are any available and how much they are?

Thanks,

KbJ
Title: Re: Internal memory expansion
Post by: Tutus on 2015.November.02. 13:36:42
I live in the UK and would be interested in 2 of these memory expansions - can someone let me know if there are any available and how much they are?

Thanks,

KbJ

It's already planned. :D We"re going to write here when it finished. We don't know the price yet.
The card will include a 10 Mhz enlargement :)
Title: Re: Internal memory expansion
Post by: slugman on 2015.November.04. 18:02:53
It's already planned. :D We"re going to write here when it finished. We don't know the price yet.
The card will include a 10 Mhz enlargement :)

Great news!
Title: Re: Internal memory expansion
Post by: keyboardjunkie on 2015.November.04. 22:55:17
Ahhh that's great news!  I don't know if I can wait!!

Looking forward to the day you have it ready for sale - and if you need a tester, I'm more than happy to test!

Thanks!

Mark.
Title: Re: Internal memory expansion
Post by: dmacoco on 2015.December.12. 07:57:27
It's already planned. :D We"re going to write here when it finished. We don't know the price yet.
The card will include a 10 Mhz enlargement :)

Good news, i hope i'll be able to buy one for my poor enterprise 64.
Title: Re: Internal memory expansion
Post by: endi on 2015.December.12. 08:39:57
just a question
a mem expansion for ep64 is equal compared to the ep128 mem? I mean in speed for example (other paramters is equal I think)
Title: Re: Internal memory expansion
Post by: geco on 2015.December.12. 10:19:25
It is equal, EP64 slower only, because everything is used from VRAM
Title: Re: Internal memory expansion
Post by: lgb on 2015.December.13. 20:58:27
It is equal, EP64 slower only, because everything is used from VRAM

I'm not sure, but as far as I can remember EP64 also had older version of EXOS ...
Title: Re: Internal memory expansion
Post by: chouimat on 2017.November.02. 14:47:31
is this board still being made?
Title: Re: Internal memory expansion
Post by: gflorez on 2017.November.02. 18:37:07
You can put a PM to szorg (https://enterpriseforever.com/profile/?u=269). He sells 1Mb internal Ram expansions.
Title: Re: Internal memory expansion
Post by: SzörG on 2017.November.02. 23:29:32
is available from 1Mb memory expansion in stock :-)
thoughtful version in small and flat size
(both versions are in the picture, the new is the red PCB) ...

if you are interested, please email to me
vortyex at gmail dot com
Title: Re: Internal memory expansion
Post by: Z80System on 2017.November.03. 23:59:01
Quote
both versions are in the picture, the new is the red PCB

Do you have both in stock, or you have only the red one ?

Are the two boards directly exchangeable ?

I mean, I have two EP boards assembled with the "big ass green" (:)!) one,
can I just pull off the existing expansion boards from the cables and plug in the new (red) one ? Without any soldering work ?

(It seems the red one has a bit different wiring than the previous one ...)
Title: Re: Internal memory expansion
Post by: gflorez on 2017.November.04. 03:12:52
thoughtful version in small and flat size

The same functions with the same wiring, only in SMD

SzörG put Saint's board only for comparing it with his new memory expansion.
Title: Re: Internal memory expansion
Post by: Z80System on 2017.November.04. 11:07:08
Quote
The same functions with the same wiring, only in SMD

I count only 8 pin on the red and 10 pin on the green,

and the red one does not seem to have a connector on the right side either ...


That does not seem the same ... where am I wrong ?

Title: Re: Internal memory expansion
Post by: Tutus on 2017.November.04. 11:37:40
I count only 8 pin on the red and 10 pin on the green,

and the red one does not seem to have a connector on the right side either ...


That does not seem the same ... where am I wrong ?

Here is the explanation :)
Only red is available.
http://szergitata.blog.hu/2017/08/18/enterprise_1088kb_ujra_enterprise_1088kb_anew (http://szergitata.blog.hu/2017/08/18/enterprise_1088kb_ujra_enterprise_1088kb_anew)
Title: Re: Internal memory expansion
Post by: Z80System on 2017.November.04. 13:29:41
Quote
Here is the explanation :)

Ok, I did not remember, that the pins of the former cable are separated,
so those can be connected (physically) in any order to a board (former or new one) ...
Title: Re: Internal memory expansion
Post by: Zozosoft on 2017.November.21. 10:01:57
The same functions with the same wiring, only in SMD
Wiring not same :-(

Now 3 different wiring exist... little crazy :evil:
[attachimg=1]
In this summary colors used from Saint, it is same with the dupont cable colors.
Title: Re: Internal memory expansion
Post by: gflorez on 2017.November.21. 10:42:58
It is annoying.... I was meaning the same signals there.
Title: Re: Internal memory expansion
Post by: Zozosoft on 2017.November.21. 10:56:05
It is annoying....
Yes. But existing "Saint cables" can be modified to universal with cutted dupont headers.
Then just need to care for the proper cable order for the currently installed board. This is why I made this colored table, for a help :-)
Title: Re: Internal memory expansion
Post by: Zozosoft on 2017.November.21. 23:14:47
Ooops :oops:
I looked the memory map with the new (red) board, and it is look very crazy :oops:
Then found the suggested wiring on Szörg's page are wrong, two wires need to be replaced.
There is the updated table:
[attachimg=1]

Universal cable which can be used with both Saint and Kotek type boards:
[attach=2][attach=3]

With Saint board:
[attach=4]

With Kotek board:
[attach=5]

Memorymap of the new red board (Kotek):
[attach=6]
Title: Re: Internal memory expansion
Post by: elmer on 2020.August.08. 19:42:26
Since there doesn't seem to be any option for internal memory expansion available at the moment, I thought that it might be interesting to see what it would take to make a new board.

This thread shows that it might not be *too* difficult to create a simple 512KB expansion board now that smarter people than me have already done the hard work of figuring things out.


Here are a few reference documents that help understand the Z80's memory timing, and using modern components on vintage computers like the Enterprise.

THE Z80 CPU : TIMING (http://www.piclist.com/techref/mem/dram/slide4.html)
Components Compatibility and Substitution (https://www.retrobrewcomputers.org/doku.php?id=buildtips:components_compatibility_and_substitution)
An Introduction to and Comparison of 74HCT TTL Compatible CMOS Logic (https://www.onsemi.com/pub/Collateral/AN-368.pdf.pdf)

I'm also attaching the datasheet for the SMT SRAM chip that JLCPCB (https://jlcpcb.com/) has in stock and available to install on any prototype PCB order.


Since Saint's original 2013 board shows that a 2-chip SRAM solution works (using a GAL for address decoding), and Kotek's board shows that the extra RAM does not need to be decoded in a single block of bank numbers, then what I'm thinking would work is a simple 2-chip board that only uses off-the-shelf components, and would not need any GAL or FPGA programming.

The address decoding would just use a single 74HCT138 set up as ...

/E0: GND
/E1: /MREQ
 E2: /RFSH
 A0: A16
 A1: A20
 A2: A21

The 8 outputs are each valid for a set of 8x64K memory areas:

/Q0: unused
/Q1: unused
/Q2: unused
/Q3: unused
/Q4: unused
/Q5: unused
/Q6: SRAM /CE for banks C0h-C3h,C8h-CBh,D0h-D3h,D8h-DBh,E0h-E3h,E8h-EBh,F0h-F3h,F8h-FBh
/Q7: unused


This would mean that any badly-behaved EP128 software that just assumed that banks F8h-FBh existed would still work.


Does that make sense to those experience people that have gone through this all before over the years?
Title: Re: Internal memory expansion
Post by: Allf on 2020.August.09. 07:22:48
Don't forget - the custom chip are on the board, not only Z80...
Title: Re: Internal memory expansion
Post by: dangerman on 2020.August.09. 12:47:45
Hi Elmer. Yes, you definitely want segments F8h-FBh otherwise a lot of software will need patching!

I'm afraid I don't have any experience of ordering SMT boards, but I can confirm that the design for a 512k SRAM expansion is very simple. A couple of years ago I built two expansions myself on strip board - one external and one internal. To my surprise they both work very well even with my bad soldering by hand - tested at 8Mhz and 12Mhz. I didn't even need a 74LS244 buffer on the external expansion.

The internal one used a single programmable logic to give continuous addresses from seg DCh to FBh.
The external one used two standard chips for the same - 74LS141 multiplexer and 74LS20 NAND gates.

But your clever solution uses just one standard chip so is even better.

Happy to help out on this if you have any questions. But it sounds like you're pretty sorted.
Title: Re: Internal memory expansion
Post by: dangerman on 2020.August.09. 22:01:14
Also to make the design even easier you can connect the data lines to the SRAM chip in any order.

And the address lines to the RAM chip can also be in any order. The only addresses that can't be swapped around are the ones you're using for /CE.

Does that make sense?
Title: Re: Internal memory expansion
Post by: gflorez on 2020.August.10. 01:09:22
Also to make the design even easier you can connect the data lines to the SRAM chip in any order.

And the address lines to the RAM chip can also be in any order. The only addresses that can't be swapped around are the ones you're using for /CE.

Don't follow this if you later want to add some FlashRom to your expansion (https://enterpriseforever.com/interface-57/internal-real-time-clock/msg62172/#msg62172).

-------------------

I am trying to search the gerbers of Saint's Ram expansion(asking him...). Or the ones of the Spanish clone(I still have not contacted  "Quest", the guy that copied it). If not found, don't you think it is easier to not reinvent the wheel? the layout seems very easy to design on Eagle or other similar program. Also, The 512KB or 1MB differences seem easy to add. We also have the GAL formulas kindly given by Saint himself (https://enterpriseforever.com/interface-57/exp1-and-exp2-pinouts/msg37744/#msg37744).

The first version from Saint.

(https://enterpriseforever.com/interface-57/exp1-and-exp2-pinouts/?action=dlattach;attach=9780;image)

This was the Spanish clone, with some differences in the tracks:

(https://i.imgur.com/cpSmbvz.jpg)
(https://i.imgur.com/5w2qZw9.jpg)

Maybe Zozo still has a 1MB Saint's PCB to take some pictures. I better want Saint's permission.

Another option can be the Kotek board. I can also make a batch if the gerbers and CPLD firmware are accessible.  The chips are SMD, but they can still  be soldered at hand with a thin iron.

-------------
Edit: I have found a picture of the second version of Saint's expansion, only upper side and not a good one, due to be black.

[attachimg=1]
Title: Re: Internal memory expansion
Post by: elmer on 2020.August.10. 05:07:07
Don't follow this if you later want to add some FlashRom to your expansion.

Absolutely! But ... if all that someone is interested in is a simple RAM expansion, then I believe that the suggestion is a good one since it might make routing the traces easier.

Heck, with SzörG's lovely SDcard interface and enough RAM, then modern users might not even see much need to ever add some FlashROM.

It all depends upon what each individual owner wants to do with their Enterprise.


I am trying to search the gerbers of Saint's Ram expansion(asking him...). Or the ones of the Spanish clone(I still have not contacted  "Quest", the guy that copied it). If not found, don't you think it is easier to not reinvent the wheel? the layout seems very easy to design on Eagle or other similar program.

I have absolutely no interest in "reinventing the wheel", nor do I believe that I have the knowledge, experience or skills to somehow invent the "best" internal RAM expansion.

I just want/need an internal RAM expansion for my Enterprise 64, and none seems to be currently available anywhere for me to buy, so I am trying to come up with an *easy* solution that requires minimal soldering or programming, that might be easy and cheap to order, and that hardware-novices could re-order themselves in the future.


When it comes to Saint's lovely design ... the GAL that he used has been obsolete for some time, and they mainly seem to available as "used" units from China. I can find some sellers of NOS parts, but they are 20x the cost of a surface-mount 74HCT138 from JLCPCB.

Other 5V GALs, such as Atmel's ATF16V8B, are still widely available and affordable, but then that would be a change in Saint's design, and I don't know if that would work.

Then, whichever GAL is used, someone has to have the right equipment, and then take the time, to program it.


You, Saint, Kotek and others have far more hardware knowledge than I will ever have, and if you, or someone else produces some boards (of whatever type), then I will probably buy one.

But if not, then is there some reason to avoid the simple 2-chip solution that I am suggesting?

With my limited knowledge, it seems to be almost identical to what both @dangerman and @Zozosoft have already had working, and have shown in other threads.
Title: Re: Internal memory expansion
Post by: elmer on 2020.August.10. 05:25:55
I am trying to search the gerbers of Saint's Ram expansion(asking him...). Or the ones of the Spanish clone(I still have not contacted  "Quest", the guy that copied it).
...
Another option can be the Kotek board. I can also make a batch if the gerbers and CPLD firmware are accessible.  The chips are SMD, but they can still  be soldered at hand with a thin iron.

I forgot to say this before ... thanks! :-)
Title: Re: Internal memory expansion
Post by: Dr.OG on 2020.August.10. 05:58:40
I think a simple external RAM expansion connected to the right side port of the computer would be nice as well, without needing to solder and modify the original HW. I know there's the SF3 card, and Pear's Dream Turbo Card, but combined with the SD-card reader connected to the cartridge bay, it would be enough for most users (and much more cheaper I suppose).
Title: Re: Internal memory expansion
Post by: dangerman on 2020.August.10. 11:18:12
I think a simple external RAM expansion connected to the right side port of the computer would be nice as well, without needing to solder and modify the original HW.

Sadly, the problem with an external RAM expansion (and why I decided to build an internal one as well) is that you need some kind of bus board or pass-through to connect an EXDOS as well. Maybe it doesn't matter if you have the cartridge SD card reader, but I can see why some people would prefer to solder something internally instead.

Title: Re: Internal memory expansion
Post by: dangerman on 2020.August.10. 11:41:08
Don't follow this if you later want to add some FlashRom to your expansion (https://enterpriseforever.com/interface-57/internal-real-time-clock/msg62172/#msg62172).

Good point about the FlashRom - that wouldn't work with my home-made expansions!  I guess it all depends how easy you want the routing on your memory expansion to be ;-)

Other 5V GALs, such as Atmel's ATF16V8B, are still widely available and affordable, but then that would be a change in Saint's design, and I don't know if that would work.

Then, whichever GAL is used, someone has to have the right equipment, and then take the time, to program it.

Do we know what GAL Saint used? Pinouts are often pretty standard so Atmel's ATF16V8B might just be a drop in replacement.

Alternatively if you were making a new board, I believe many circuit manufacturers will programme the GALs for you when get the board made up. (Although I don't know what that does to the cost and IMHO, there's nothing wrong with your 74HCT138 idea.)

Incidentally, the ATF16V8B is exactly the one that I used in my internal memory expansion. They're very easy to program using cheap universal programmers.
Title: Re: Internal memory expansion
Post by: gflorez on 2020.August.10. 12:06:13
Thanks Elmer for putting me near Saint or Kotek.... My only merit on all these years has been to take risks with my Enterprise to learn more in return. My first EP can be the proof that they build them very strong. Almost all the things I have achieved where by means of knocking and knocking my head against the information available. Thanks, Zozo, Geco, Pear, LGB, IstvanV, and others for being so patient with my constant questions....

Also, sorry, I don't want you to think that I am misprising your design. Only that my message was long, and yesterday was too late to continue writing.

But looking forward, your approach is neat and wonderful in its simplicity, enough to run SymbOS or other old or modern programs with very few components.

On the other hand, I think like Dr.OG: with the arrival of the SD cartridge you no more need to have something connected to the expansion port so, it is the obvious place to connect a Ram expansion if you fear to break the Enterprise while dismantling it completely....

Also, there is a thing I don't understand: why ordering the PCB builder to solder the components? these jobs are not cheap, and misses you the enjoyment of soldering the PCB by yourself.

A last thing: EDGE connectors are expensive if not bought in China, so you must consider the overprice against the easiness to connect it. And, even if you have the Edge connector, it always need some trimming. I can aid you, as I have some experience on that.

Ok...., I offer my aid,  daring and interest on all that my limited skills will allow. .
Title: Re: Internal memory expansion
Post by: gflorez on 2020.August.10. 12:17:18
About programmable chips. Don't think that is difficult to manage them, the only problem they have is obsolescence. Lattice's GAL are obsolete now, and also the substitutes.

But you can find the way to program them reading a lot of web pages... I and others have already done that, so you don't need to take that path. I have now a collection of programmers, some very old and others new, all very cheap. The usual problem is with the software that controls them, but you always can use Google to find it.
Title: Re: Internal memory expansion
Post by: elmer on 2020.August.12. 05:49:55
I think a simple external RAM expansion connected to the right side port of the computer would be nice as well, without needing to solder and modify the original HW.

That's a perfectly reasonable desire, especially for collectors that don't wish to modify original hardware, but don't forget ... when Enterprise itself offered to expand 64KB machines to 128KB, they did it with an internal memory expansion that required opening the case.

From my own personal point of view, if I've got to open the case to upgrade the EXOS version from 2.0 anyway (presumably with a hardware mod and Zozosoft's EXOS 2.4), then I might as well install the extra RAM internally as well at the same time and then be left with a clean-looking machine.


Do we know what GAL Saint used? Pinouts are often pretty standard so Atmel's ATF16V8B might just be a drop in replacement.

According to both the photos that I've seen, and the GAL programming file that gflorez pointed out, Saint used a Lattice GAL16V8 (datasheet attached).

The photos show that he started with the 25ns part, and then used the 15ns part later on (probably just because that's what he could find to buy).


It looks like the GAL16V8 is both pin and electrically compatible with Atmel's ATF16V8B, so there *should* be no problem using the newer chip.


Alternatively if you were making a new board, I believe many circuit manufacturers will programme the GALs for you when get the board made up. (Although I don't know what that does to the cost and IMHO, there's nothing wrong with your 74HCT138 idea.)

Incidentally, the ATF16V8B is exactly the one that I used in my internal memory expansion. They're very easy to program using cheap universal programmers.

JLCPCB do actually offer an SMT version of the ATF16V8B, but honestly, both the Lattice and Atmel GALs have a 20 year rating for the programming, and I really don't like the idea of a new memory expansion board on a 35 year old computer having a built-in time limit that will eventually cause the board to fail.

The chips on Saint's design are both socketed, so at least the GAL can be easily re-programmed if it starts to go bad, but we lose that option if we use a SMT version of the ATF16V8B.


So, from my point of view, that either means choosing Saint's design with its socketed DIP chips, which means more expensive parts and more soldering ... or choosing to try to finish off the 74HCT138 surface-mount design and having the SMT chips mounted at the factory, which means using cheaper components and having less soldering to do when the boards are received.


As it is, I just received a new TL866II Universal Programmer to replace my very old and broken EPROM Programmer from the 1990s, and so I should now be able to program both the newer ATF16V8B chips, or the older GAL16V8 chips. :)


On the other hand, I think like Dr.OG: with the arrival of the SD cartridge you no more need to have something connected to the expansion port so, it is the obvious place to connect a Ram expansion if you fear to break the Enterprise while dismantling it completely....

I agree, and I'm not looking forward to taking my Enterprise apart, but I don't see much option if it still has EXOS 2.0 inside.

Then, as you say, there is the issue of the external solution needing an expensive edge connector, and also really needing to have a case for the board so that it is both physically supported and protected.


Also, there is a thing I don't understand: why ordering the PCB builder to solder the components? these jobs are not cheap, and misses you the enjoyment of soldering the PCB by yourself.

Hahahaha ... we're very different people. I'm afraid that I really don't enjoy soldering, and there is no way that I would I would even attempt to try to solder SMT components.

Yes, I *can* solder; I both played with electronics as a kid, and I did some electronics classes at university, but really I'm a software guy, and not a hardware guy.


As for the cost, it *looks* like JLCPCB will charge $20 USD for the setup, and then maybe $0.1 USD per board for the soldering ... which seems reasonable if someone orders 5 or 10 boards.

I don't know if there will be other charges, and I won't know that until I have created a board layout that I can upload to them and get a quote.

It is slow work since I've never done it before. :(
Title: Re: Internal memory expansion
Post by: dangerman on 2020.August.13. 22:12:30
but honestly, both the Lattice and Atmel GALs have a 20 year rating for the programming, and I really don't like the idea of a new memory expansion board on a 35 year old computer having a built-in time limit that will eventually cause the board to fail.

Yes, I'd forgotten about the time limit. That would be very annoying indeed. You make a good case for using standard parts.
Title: Re: Internal memory expansion
Post by: gflorez on 2020.August.14. 00:14:39
Which other time limits could exist on other components and we can't even predict them.....

We shouldn't live with that fear, every problem will be fixed in strict order of happening....

Do you think that the humble Enterprise was made to endure 35 years of use(...or more I hope)?
Title: Re: Internal memory expansion
Post by: emptiness on 2020.August.16. 23:01:09

I have absolutely no interest in "reinventing the wheel", nor do I believe that I have the knowledge, experience or skills to somehow invent the "best" internal RAM expansion.

I just want/need an internal RAM expansion for my Enterprise 64, and none seems to be currently available anywhere for me to buy, so I am trying to come up with an *easy* solution that requires minimal soldering or programming, that might be easy and cheap to order, and that hardware-novices could re-order themselves in the future.

Same here. I'd be happy to buy a couple of boards from someone or failing that solder a board if there's a design that I'm capable of assembling.

elmer, you're way ahead of me, if you do finalise a design and get as far as fabricating some boards please let me know. I'm happy to chip and in help with costs.
Title: Re: Internal memory expansion
Post by: elmer on 2020.August.19. 20:27:41
Which other time limits could exist on other components and we can't even predict them.....

We shouldn't live with that fear, every problem will be fixed in strict order of happening....

Do you think that the humble Enterprise was made to endure 35 years of use(...or more I hope)?

I agree, there's no point in worrying if something may break over time ... everything does eventually!

I see nothing wrong with using a GAL, I would just want it to be easy to reprogram if it starts to lose its flash-memory.

IMHO, that means that using a DIP-format GAL would be more sensible than using a SMT-format GAL, that's all that I'm saying.


elmer, you're way ahead of me, if you do finalise a design and get as far as fabricating some boards please let me know. I'm happy to chip and in help with costs.

I've had some help from a friend, and I'm (slowly) getting closer to having a simple board layout that could work.

Even if I can get a design where JLCPCB integrates all the SMT components, there will still be the EXP1 and EXP2 connectors that will need to be soldered on, plus the soldering on the Enterprise motherboard for the EXP1 connector and the EXP2 cable.

All of those should be low-tech 0.1" soldering that old folks like me are still capable of handling. ;)
Title: Re: Internal memory expansion
Post by: elmer on 2020.August.19. 21:55:12
Now 3 different wiring exist... little crazy :evil:

(https://enterpriseforever.com/index.php?action=dlattach;topic=891.0;attach=19983;image)


Universal cable which can be used with both Saint and Kotek type boards:

(https://enterpriseforever.com/index.php?action=dlattach;topic=891.0;attach=19986;image)

Urrrrggghhh ... that's annoying! :(

Are there actually any people using Saint or Kotek wiring that would even be interested if there was a new 512KB memory board available?

The reason that I ask is that the "original" wiring is probably the one that makes the most sense to me for a new board. The reason for that is because it allows for a simple 90 degree fold in the cable, just the way that the original Enterprise memory board cables were folded.
Title: Re: Internal memory expansion
Post by: geco on 2020.August.19. 23:16:00
Sorry if i misunderstood your post. I use probably Saint's 1MB board ( i did not open my ep), but if there is a new board also, i am interested.
Title: Re: Internal memory expansion
Post by: elmer on 2020.August.20. 21:58:01
If I didn't make myself clear before, this picture shows how the EXP2 cable was folded on the original Enterprise memory expansion board, which causes the different order of pins on the 1x10 connector in comparison to how Saint ran his cable.

(http://ep128.hu/Album/Pic/EP_alaplap.jpg)


Sorry if i misunderstood your post. I use probably Saint's 1MB board ( i did not open my ep), but if there is a new board also, i am interested.

I suspect that I wasn't clear in what I was asking.

I am trying to decide whether to use Saint's pin ordering of the EXP2 cable, or to use the original Enterprise pin ordering.

If folks (like you) who are already using Saint's boards are actually interested in having yet-another memory expansion board, even though it only has 512KB, then I should probably just use Saint's pin ordering so that people can keep on using the cable that they've already wired onto their motherboard.
Title: Re: Internal memory expansion
Post by: Judge on 2020.August.20. 22:53:10
I suspect that I wasn't clear in what I was asking.
I am trying to decide whether to use Saint's pin ordering of the EXP2 cable, or to use the original Enterprise pin ordering.
If folks (like you) who are already using Saint's boards are actually interested in having yet-another memory expansion board, even though it only has 512KB, then I should probably just use Saint's pin ordering so that people can keep on using the cable that they've already wired onto their motherboard.

I don't think it matters. You can connect this cable to all memory cards.

[attach=1]

[attach=2]

[attach=3]

[attach=4]

[attach=5]

The Kotek is missing two GND. This is the difference ...
Title: Re: Internal memory expansion
Post by: Tutus on 2020.August.21. 09:24:22
Exactly. I don't understand what the problem is. You can design a card based on the documentation. Ok, it's already sold out and all the makers are gone. But it can be solved!
Title: Re: Internal memory expansion
Post by: Allf on 2020.August.21. 14:52:52
I assume the 2x5-pin connector on the original German description on the link (64k-Static-Internal.pdf) (https://enterpriseforever.com/hardware/what-internal-ram-expansion/?action=dlattach;attach=25274) is annoying for elmer. Topic link (https://enterpriseforever.com/hardware/what-internal-ram-expansion/msg80006/#msg80006)
Title: Re: Internal memory expansion
Post by: Judge on 2020.August.21. 15:01:47
I already see your problem ...

Use a cable like this:

 [attach=1]

The order of the threads is changeable.
Title: Re: Internal memory expansion
Post by: elmer on 2020.August.22. 01:55:05
The order of the threads is changeable.

Yes, that is one good solution. :)

Another possibility is to just use two 5-pin DuPont cables, and flip them as needed.
Title: Re: Internal memory expansion
Post by: gflorez on 2020.August.22. 23:48:06
I have added an upper picture of the second version of Saint's expansion here (https://enterpriseforever.com/interface-57/exp1-and-exp2-pinouts/msg79954/#msg79954).
Title: Re: Internal memory expansion
Post by: elmer on 2020.August.23. 00:47:55
I have added an upper picture of the second version of Saint's expansion here (https://enterpriseforever.com/interface-57/exp1-and-exp2-pinouts/msg79954/#msg79954).

Thanks, that's really nice to see! :)

If I'm seeing it correctly, most of the layout looks identical to the earlier board, but he's added an extra decoupling capacitor for the piggyback SRAM chip, and also added a trace and via/hole for connecting the /CE pin on the piggyback SRAM chip.


BTW, you mentioned earlier that you were going to contact SainT and see if he would share the schematic/Gerbers for his expansion board. Did you ever get a response from him?

I see that he's been on the AtariAge forum recently, so he's still around.
Title: Re: Internal memory expansion
Post by: Judge on 2020.August.23. 10:09:53
BTW, you mentioned earlier that you were going to contact SainT and see if he would share the schematic/Gerbers for his expansion board. Did you ever get a response from him?
I see that he's been on the AtariAge forum recently, so he's still around.

Someone who speaks good English can ask here (https://www.retrohq.co.uk/contactus/)... :)
Title: Re: Internal memory expansion
Post by: gflorez on 2020.August.23. 13:04:43
I have already asked him by mail. I am waiting an answer.
Title: Re: Internal memory expansion
Post by: Judge on 2020.August.23. 14:44:13
I have already asked him by mail. I am waiting an answer.

It's OK then... :smt023  We hope he will respond :cry:
Title: Re: Internal memory expansion
Post by: elmer on 2020.August.23. 22:40:19
Also to make the design even easier you can connect the data lines to the SRAM chip in any order.

And the address lines to the RAM chip can also be in any order. The only addresses that can't be swapped around are the ones you're using for /CE.

Yes, doing this really has made the routing a lot simpler, and dramatically reduced the number of vias that are needed on the board.

Here is the schematic and PCB design that I've come up with, using the same 1x10 pin ordering for the EXP2 connector that SainT's board uses, just to keep things easier for people.

The board itself is a tiny bit smaller than SainT's board, but not by a lot.

Most of that is because of the size of the 1x10 and 2x14 headers, but since this is my first PCB design, I've been very careful to try to keep large spaces between the components, and use wider tracks than are probably necessary.

I still need to have this sanity-checked for errors by some friends, and I'd also love it if the electronics folks here could take a look and see if anything looks bad.
Title: Re: Internal memory expansion
Post by: dangerman on 2020.August.24. 11:35:35
Wow - great work! :smt041 Not worrying about the order of the address and data lines makes life much easier doesn't it?

I'm afraid I'm not good enough at electronics to reliably check it. Although I do have a question for my own learning if that's okay. Why are there 3 capacitors? When I designed my [amateur] expansion I just had one capacitor to smooth the supply to the 512k chip. So it turns out I should have put one on the ATF16V8 as well. But why the 3rd capacitor?

Basically I didn't really know what I was doing and was amazed that what I did worked at all. :)
Title: Re: Internal memory expansion
Post by: elmer on 2020.August.24. 20:41:21
Wow - great work! :smt041

Thanks! I've already made some small changes based upon feedback, and I think that I will need to make a few more.


Why are there 3 capacitors? When I designed my [amateur] expansion I just had one capacitor to smooth the supply to the 512k chip. So it turns out I should have put one on the ATF16V8 as well. But why the 3rd capacitor?

The 3rd capacitor is a larger 10uf decoupling capacitor to smooth out the power supply for the whole expansion-board.

The advice that I got from friends was ...

For decoupling caps you'll want one small (.1uF) capacitor per VCC pin and one larger (4.7uF or 10uF) for a the whole board. You can use small ceramic caps for these. Keep the .1uF caps as close to the VCC pin + paired ground as possible.

In certain technical books like "The Art of Electronics" there is an explanation of the theory behind how to choose the value... but nobody ever bothers with that until they have a problem. These (0.1 and 10uF) are ready-made rule-of-thumb solutions.


That matches the advice here (https://www.autodesk.com/products/eagle/blog/what-are-decoupling-capacitors/).


You can see the same board-level large (low frequency) decouping capacitor on the original EP128 board schematic here (http://ep128.hu/Ep_Hardware/Pic/EP128_expansion.jpg) and in the photo here (http://ep128.hu/Album/Pic/EP_alaplap.jpg), but they were using a big 100uf capacitor because of the large number of higher-power TTL chips on that old board.


Not worrying about the order of the address and data lines makes life much easier doesn't it?

Oh yes, MUCH easier! ;)

But now that I have a tiny bit more experience, I'm going to go back a step and see if I can get the pins in order again, and try to add the socket for a FLASH ROM chip onto the board.
Title: Re: Internal memory expansion
Post by: dangerman on 2020.August.24. 21:18:27
Thanks for the info. Starts to make sense now.

Good luck with adding the Flash ROM. I expect you know already but the original EXOS will only find ROMs in segments which are multiples of 16. So you'll need Zozosoft's unofficial EXOS upgrade to recognise system ROMs that don't start on 256k boundaries. 
Title: Re: Internal memory expansion
Post by: gflorez on 2020.August.24. 23:24:17
Once they will add the Ram expansion, adding Zozo's modified EXOS seems a trivial step.

Great decision to put a FlashRom. Adding the /WE signal even can allow to write it in situ. Don't use Winbond or other cheap makers, better AMD. Zozo can modify his SD cartridge flasher for your memory expansion.

A good range to put a 512KB Rom zone is 60-7F, said by Zozo that it is a scarcely used  area. And for the Ram, like Saint's expansion, filling F0-FB, E0-EF, DC-DF, if 512KB, or F0-FB, E0-EF, D0-DF, C0-CF, BC-BF if 1MB.

Simbiface3 also uses 60-7F as a Rom zone but it can put the Roms in any place so no problem.
Title: Re: Internal memory expansion
Post by: elmer on 2020.August.25. 18:56:32
Once they will add the Ram expansion, adding Zozo's modified EXOS seems a trivial step.

I agree ... if you've already had to get inside the Enterprise to solder wires onto the EXP2 connector, then adding one more wire so that you can use EXOS 2.4 seems pretty trivial.


Great decision to put a FlashRom. Adding the /WE signal even can allow to write it in situ. Don't use Winbond or other cheap makers, better AMD. Zozo can modify his SD cartridge flasher for your memory expansion.

A good range to put a 512KB Rom zone is 60-7F, said by Zozo that it is a scarcely used  area. And for the Ram, like Saint's expansion, filling F0-FB, E0-EF, DC-DF, if 512KB, or F0-FB, E0-EF, D0-DF, C0-CF, BC-BF if 1MB.

Simbiface3 also uses 60-7F as a Rom zone but it can put the Roms in any place so no problem.

From what I can see, AMD don't *seem* to be making 5V flash chips anymore, especially in PDIP format.

The modern 5V part that is being recommended to me is Microchip's SST39F040, which uses the same pin layout as AMD's old 29F040.


Unless I change the address decoding logic from the simple 74HCT138, then I can't decode any of those ranges like that.

The obvious choice would be to use output 4 on the 74HCT138, which would decode to banks 80h-83h, 88h-8Bh, 90h-93h, 98h-9Bh, A0h-A3h, A8-ABh, B0h-B3h, and B8-BBh.

The other choice would be to use output 2 on the 74HCT138, which would decode to banks 40h-43h, 48h-4Bh, 50h-53h, 58h-5Bh, 60h-63h, 68-6Bh, 70h-773h, and 78-7Bh.


Is there a list anywhere of what expansion-bus cards use which segments?
Title: Re: Internal memory expansion
Post by: geco on 2020.August.25. 20:36:56
Unfortunately i did not find any documentation, but i am nearly sure that at 80 and above it there is no ROM defined, between 40-7F the chance is a bit bigger, but there should not be so much.
there is only one problem with these 2 possibilities, most of old non EXOS compatible programs will not run.
Title: Re: Internal memory expansion
Post by: elmer on 2020.August.25. 22:49:37
Great decision to put a FlashRom.

I've been looking at this all day, and I'm afraid that I can't find any way to add that PDIP socket for the FLASH chip, and still end up with any kind of sensible board layout.

I'm sorry, I just don't have good enough design skills, and so I'm going to have to abandon the FLASH idea, and just keep the board as a simple 512KB SRAM expansion.


People who need lots of FLASH ROM space already have the Symbiface3 card that you've done such excellent work on, and perhaps in the future they'll also have Pear's lovely looking Dream Turbo Card.


Unfortunately i did not find any documentation, but i am nearly sure that at 80 and above it there is no ROM defined, between 40-7F the chance is a bit bigger, but there should not be so much.

This (https://enterpriseforever.com/hardware/6mhz-and-more/msg68656/#msg68656) is the only thing that I could find.

Looking at that, there doesn't seem to be any conflict with the 74HCT138 segment mappping for the SRAM that I am proposing to use, even if it is a bit wasteful.
Title: Re: Internal memory expansion
Post by: gflorez on 2020.August.25. 23:46:56
Yes, a simple solution has to accomplish the rule of being simple....
Title: Re: Internal memory expansion
Post by: elmer on 2020.August.26. 21:19:23
Here are the PDF versions of the latest changes to the simple board.

It's mainly just a case of pushing some traces around in the hope of making it easier for the manufacturer to add tooling holes.

The other important change is to increase the size of the thermal reliefs on all of the ground pins in order to make them easier to solder (great tip from a friend!).
Title: Re: Internal memory expansion
Post by: dangerman on 2020.August.29. 10:42:08
I've been looking at this all day, and I'm afraid that I can't find any way to add that PDIP socket for the FLASH chip, and still end up with any kind of sensible board layout.

If you're going to program the chip in situ on the actual Enterprise, then you can still use the trick of swapping the order of address lines and data lines.

But maybe it's still too complicated to add the FLASH.
Title: Re: Internal memory expansion
Post by: elmer on 2020.August.29. 15:56:12
If you're going to program the chip in situ on the actual Enterprise, then you can still use the trick of swapping the order of address lines and data lines.

Yes, that's right. :)


But maybe it's still too complicated to add the FLASH.

It is, at least for me.

Putting everything on one side of the PCB makes the board so big that I think that I would have needed to add holes for the board-supports that the original EP128 RAM board uses.

It is safer to take things easy for my first board design.


I've responded to feedback from friends, and made another small change to the power rail on the board ... and it is finished (I hope)!

I've placed an SMT production order at JLCPCB, and should hopefully receive the populated boards in a few weeks.

If it works in my EP64, then I should have a few spare boards to sell on to anyone that wants one.
Title: Re: Internal memory expansion
Post by: dangerman on 2020.August.29. 17:43:54
Excellent work. :smt041

Btw, what program did you use to do the design?

Title: Re: Internal memory expansion
Post by: elmer on 2020.August.29. 19:33:31
Excellent work. :smt041

Thanks! Let's hope that it actually works!


Btw, what program did you use to do the design?

I used the free downloadable version of EasyEDA (https://easyeda.com/), initially because of its close links with JLCPCB, and LCSC (the Chinese parts distributor that owns both JLCPCB and EasyEDA).

Then I tried the free version of Eagle, thinking that it must be the more "professional" and "capable" solution, but I found it absolutely horrible to use, so I went back to EasyEDA.
Title: Re: Internal memory expansion
Post by: emptiness on 2020.August.29. 19:35:14
I've placed an SMT production order at JLCPCB, and should hopefully receive the populated boards in a few weeks.

Cool, what's the minimum order quantity?

If it works in my EP64, then I should have a few spare boards to sell on to anyone that wants one.

I'd definitely be interested
Title: Re: Internal memory expansion
Post by: elmer on 2020.August.29. 20:50:17
Cool, what's the minimum order quantity?

IIRC, the order quantity for PCB boards is in multiples of 5.

But they have a special option to order 5 boards but only get the SMT chips installed on 2 of the boards (for testing designs).

If you did that, then shipping and other overheads would significantly bump up your per-board price, but it would still be a good way to get boards made if nobody here has any to sell.

Once I've made sure that the design works, and have sold off the extra boards (I ordered 10 to keep the per-board price low), then I'll upload the complete set of design files and Gerbers so that anyone can order more boards in the future.


I'd definitely be interested

Thanks!
Title: Re: Internal memory expansion
Post by: emptiness on 2020.August.30. 13:33:30
One thing I've not yet understood is how the Enterprise senses the amount of RAM available. Does it probe memory on startup or is there logic in the RAM expansion to indicate how much RAM is present?
Title: Re: Internal memory expansion
Post by: geco on 2020.August.30. 14:41:20
i did not check, but i think it goes over the 02-FFh range and checks if it is RAM if yes, and the RAM is error free, it stores in the memory, if it finds  ROM, it checks if it starts with TEST_ROM or EXOS_ROM, if yes, then call it at address c00ah with different action codes, if i remember well 1st with ROM initialize, if it was successful segment of the ROM and start position of it's allocated memory if it has and on which segment, otherwise 0000h,00h is stored in system segment (FFh). So all available ROMs stored in FFh segment each have 4 bytes RAM definitions follow it, each RAM segment has 1 byte definition. Page0 segment is not in the list.
Title: Re: Internal memory expansion
Post by: dangerman on 2020.August.30. 16:47:08
One thing I've not yet understood is how the Enterprise senses the amount of RAM available. Does it probe memory on startup or is there logic in the RAM expansion to indicate how much RAM is present?

At startup, the EXOS ROM tries writing to each segment to check if there is RAM there. The hardware doesn't provide any extra information, it's tested by software.
Title: Re: Internal memory expansion
Post by: emptiness on 2020.August.30. 19:30:15
At startup, the EXOS ROM tries writing to each segment to check if there is RAM there. The hardware doesn't provide any extra information, it's tested by software.

Thanks geco & dangerman
Title: Re: Internal memory expansion
Post by: elmer on 2020.September.10. 23:38:43
The boards have arrived from China ... now I've got to wait for the headers to arrive, and then I've still got to wire up an RGB cable for my monitor before I can actually make sure that these work (or not)! ;)

[attach=1]
Title: Re: Internal memory expansion
Post by: geco on 2020.September.11. 08:03:36
Looks cool :)
Title: Re: Internal memory expansion
Post by: dangerman on 2020.September.12. 10:54:00
Awesome news :smt041
Title: Re: Internal memory expansion
Post by: Wolfgang on 2020.September.13. 15:04:01
As I am new to EP (yes I got my EP64 from Egypt), I followed this great thread and built my own memory extension (prototype). I am using a GAL16V8 for address decoding and a AS6C4008 SRAM chip.
I just finished my prototype and at least the boot screen seems to work. It is a bit scary to unplug and reconnect the  keyboard membrane since it seems to be very thin, so no real tests yet.
Title: Re: Internal memory expansion
Post by: elmer on 2020.September.13. 19:03:20
As I am new to EP (yes I got my EP64 from Egypt), I followed this great thread and built my own memory extension (prototype). I am using a GAL16V8 for address decoding and a AS6C4008 SRAM chip.
I just finished my prototype and at least the boot screen seems to work. It is a bit scary to unplug and reconnect the  keyboard membrane since it seems to be very thin, so no real tests yet.

Congratulations! It is excellent to see another successful breadboard circuit, just like Dangerman's pictures a few pages ago. :)

I see that you have added a header to EXP2 instead of wiring the cable directly into the motherboard ... how is that working out for you?

I was under the impression that there isn't enough physical height inside the case at that point for a header and DuPont connectors, which is why SainT and the others wired the cable directly into the motherboard.

Have I misunderstood the earlier posts?

It would certainly be easier to use 2 5-pin DuPont cables instead of soldering the wires directly into the motherboard.
Title: Re: Internal memory expansion
Post by: Wolfgang on 2020.September.13. 19:55:53
Congratulations! It is excellent to see another successful breadboard circuit, just like Dangerman's pictures a few pages ago. :)

I see that you have added a header to EXP2 instead of wiring the cable directly into the motherboard ... how is that working out for you?

I was under the impression that there isn't enough physical height inside the case at that point for a header and DuPont connectors, which is why SainT and the others wired the cable directly into the motherboard.

Have I misunderstood the earlier posts?

It would certainly be easier to use 2 5-pin DuPont cables instead of soldering the wires directly into the motherboard.

Thanks. Unfortunately, I was too optimistic about EXP2. I can close the top, but it bends the plastic out about 1mm. I will remove the header or at least the front row and solder the cables directly. Btw., I was not able to use a standard double-row header on EXP1. It seems the distance between the two rows is off. I used two single rows instead.
Title: Re: Internal memory expansion
Post by: elmer on 2020.September.13. 21:12:11
Unfortunately, I was too optimistic about EXP2. I can close the top, but it bends the plastic out about 1mm.

That's good to know, I'm sorry that you found out the hard way! ;)


Btw., I was not able to use a standard double-row header on EXP1. It seems the distance between the two rows is off. I used two single rows instead.

I saw that you've used the male header on the motherboard's EXP1, rather than the female header (which is how SainT's board seems to usually be installed) ... I wonder if that has anything to do with the distance problem.

The solder tails on a female header are usually a bit thinner and more flexible than the solder tails on a male header.
Title: Re: Internal memory expansion
Post by: Wolfgang on 2020.September.14. 18:25:43
I removed the header. Now I can close it properly. :)
I also replaced the 7805s with OKI-78SR; quite the difference now......
Title: Re: Internal memory expansion
Post by: elmer on 2020.September.15. 21:01:03
I also replaced the 7805s with OKI-78SR; quite the difference now......

That's a neat little replacement for the 7805! :)

Why did you make the change? Were you having problems with your EP64?
Title: Re: Internal memory expansion
Post by: Wolfgang on 2020.September.15. 21:38:12
That's a neat little replacement for the 7805! :)

Why did you make the change? Were you having problems with your EP64?

It is more of a habit. I usually replace every 7805 in old computers either with the OKI-78SR or the TSR 1-2450 in order to reduce the heat. I generally prefer the TSR 1-2450, but they don't fit in the EP without removing the cooler and that would leave an ugly hole.
Title: Re: Internal memory expansion
Post by: gflorez on 2020.September.16. 03:41:25
The TracoPower can be installed(TSR 1-2450, or even better the 2 Amp TSR 2-2450), I did it on one of my EPs, but some bending has to be done on its little pins.
Title: Re: Internal memory expansion
Post by: Wolfgang on 2020.September.16. 08:10:41
The TracoPower can be installed(TSR 1-2450, or even better the 2 Amp TSR 2-2450), I did it on one of my EPs, but some bending has to be done on its little pins.
This worked for me with the front regulator, but not for the rear one. The space between the power connector and the cooler was too small to get the Traco in. May this is only be an ISSUE 4 problem?
Title: Re: Internal memory expansion
Post by: dangerman on 2020.September.16. 10:34:15
Unfortunately, I was too optimistic about EXP2. I can close the top, but it bends the plastic out about 1mm.

Yes - I found that out the hard way too :(

Btw., I was not able to use a standard double-row header on EXP1. It seems the distance between the two rows is off. I used two single rows instead.

I had forgotten this, but I remember having a slight problem too! I seem to recall that the official boards in the EP128 are directly attached by 28 individual tall pins, so for them the off-spacing wasn't a problem.
Title: Re: Internal memory expansion
Post by: emptiness on 2020.September.18. 07:46:17
It is more of a habit. I usually replace every 7805 in old computers either with the OKI-78SR or the TSR 1-2450 in order to reduce the heat. I generally prefer the TSR 1-2450, but they don't fit in the EP without removing the cooler and that would leave an ugly hole.

Thanks for this. I suspect there is an issue with one of the 7805s on my enterprise and was planning to replace both with new 7805s but will use OKI-78SR now.
Title: Re: Internal memory expansion
Post by: emptiness on 2020.September.27. 22:52:24
The boards have arrived from China ... now I've got to wait for the headers to arrive, and then I've still got to wire up an RGB cable for my monitor before I can actually make sure that these work (or not)! ;)

(Attachment Link)

Any luck? Did the expansion work?
Title: Re: Internal memory expansion
Post by: elmer on 2020.September.28. 17:01:35
Any luck? Did the expansion work?

Sorry, there have been many distractions. I still haven't wired up my video cable, which I need to do before seeing if the memory boards work.

Hopefully I'll know soon.
Title: Re: Internal memory expansion
Post by: Wolfgang on 2020.September.28. 17:21:58
Not to compete with the professionals here, but as a personal learning experience, I also created a pcb of my GAL based SRAM solution. It was a pain to create (I used KiCad) since I have never done anything like this before. Now I am really nervous if this is going to work at all. :roll:
Title: Re: Internal memory expansion
Post by: elmer on 2020.September.28. 19:21:10
Now I am really nervous if this is going to work at all. :roll:

Hahaha ... me too with my board! ;)
Title: Re: Internal memory expansion
Post by: elmer on 2020.October.05. 19:07:54
Sorry, there have been many distractions. I still haven't wired up my video cable, which I need to do before seeing if the memory boards work.

Quick update ... I have finally had the time to solder the video cable, and my Egyptian Enterprise is confirmed to be fully working (just as the seller advertised)!

Now I can open it up and have a go at doing the internal upgrades, and so test if the new memory board design actually works. :)
Title: Re: Internal memory expansion
Post by: Judge on 2020.October.05. 20:31:46
Quick update ... I have finally had the time to solder the video cable, and my Egyptian Enterprise is confirmed to be fully working (just as the seller advertised)!

Then the cable works well.I am very pleased. :smt026
Title: Re: Internal memory expansion
Post by: elmer on 2020.October.06. 02:11:38
Then the cable works well.I am very pleased. :smt026

Yes, thank you!

My terrible job of soldering on the SCART connector end of the cable really doesn't do justice to your clean work on the Enterprise end of the cable! ;)
Title: Re: Internal memory expansion
Post by: Judge on 2020.October.06. 11:00:17
My terrible job of soldering on the SCART connector end of the cable really doesn't do justice to your clean work on the Enterprise end of the cable! ;)

If I knew the scart connector was good for you, I would have soldered it. Sorry! :oops:
Title: Re: Internal memory expansion
Post by: Wolfgang on 2020.October.09. 14:25:31
My pcbs arrived today:
[attach=1]
[attach=2]
and everything seems to work okay. :)
[attach=3]
[attach=4]
Title: Re: Internal memory expansion
Post by: gflorez on 2020.October.09. 14:56:29
Great! the second internal Ram expansion on the same week...

I think that Pear's L-connector (https://enterpriseforever.com/memoria/512k-belso-ram-bovites-ii/msg80521/#msg80521) solution for the EXP2 header can suit perfectly your project.
Title: Re: Internal memory expansion
Post by: elmer on 2020.October.10. 04:43:14
My pcbs arrived today:
and everything seems to work okay. :)

Congratulations! :mrgreen:
Title: Re: Internal memory expansion
Post by: elmer on 2020.October.10. 05:00:23
If I knew the scart connector was good for you, I would have soldered it. Sorry! :oops:

No need to be sorry, if I had known for sure what resistors my Panasonic BT-H1390YN needed, then I would have let you! ;)

I wanted the bare cable so that I could do my own soldering and experiment with different resistor values (if I needed to).

As it was, my 1st attempt worked great ... 330 ohm resistors on R, G, and B, and no resistor on CSYNC.

That will probably work as well for anyone that uses other professional broadcast monitors such as the Sony PVM series.
Title: Re: Internal memory expansion
Post by: Wolfgang on 2020.October.10. 20:20:17
My first 1MB prototype:
[attach=1]
2nd chip not even soldered yet:
[attach=2]
yeah - works! :smt026
[attach=3]
[attach=4]

I need to check if I can still put the top on though.....
Title: Re: Internal memory expansion
Post by: gflorez on 2020.October.10. 20:44:39
Great!

I think that the case will fit if you bend a little the EXP2 leads to the left. The eight of the piggy-back Ram chips is the same as the ones on the Saint's Ram expansions I have installed on my EPs, so that will not be a problem.
Title: Re: Internal memory expansion
Post by: Wolfgang on 2020.October.10. 20:46:15
Great!

I think that the case will fit if you bend a little the EXP2 leads to the left. The eight of the piggy-back Ram chips is the same as the ones on the Saint's Ram expansions I have installed on my EPs, so that will not be a problem.

Yes, works nicely. I don't even have to bend anything. :)
Title: Re: Internal memory expansion
Post by: Wolfgang on 2020.October.11. 13:54:13
And here are the files for anybody who wants to produce the board.
I would be glad to see pictures of produced boards. :)

Stay healthy!


btw.: J1 has the same order as Saints boards - i.e. GND GND A21 A19 A17 +5V GND A20 A18 A16
 
Title: Re: Internal memory expansion
Post by: gflorez on 2020.October.11. 18:52:21


Yess, it is a wonderful heritage.....
Title: Re: Internal memory expansion
Post by: elmer on 2020.October.12. 06:28:12
My first 1MB prototype:
...
yeah - works! :smt026

Excellent work!

I was worried when I saw the very narrow width of your +5V track, but it looks like it was OK ... congratulations! :)


May I ask ... as another newcomer here, what interests you about having 1MB RAM instead of 512KB RAM?

Have I missed hearing about something fun that needs that much RAM on the Enterprise?
Title: Re: Internal memory expansion
Post by: Wolfgang on 2020.October.12. 08:55:04
Excellent work!

I was worried when I saw the very narrow width of your +5V track, but it looks like it was OK ... congratulations! :)

Yes, I had the same worry but was not able to change it, since I am an absolute beginner with KiCad. 


May I ask ... as another newcomer here, what interests you about having 1MB RAM instead of 512KB RAM?

Have I missed hearing about something fun that needs that much RAM on the Enterprise?
For no sensible reason, just intellectual curiosity. And my GAL has so many unused outputs. :lol:
Title: Re: Internal memory expansion
Post by: gflorez on 2020.October.12. 09:08:55
I can think at least on two good reasons to have 1MB of Ram on the EP:

First, because the amazing SymbOS can manage all that memory.

And second, because there has always been the challenge of knowing if it would be possible for EXOS to reach the maximum of 4MB of addressable memory that was promised....
Title: Re: Internal memory expansion
Post by: elmer on 2020.October.14. 05:48:12
For no sensible reason, just intellectual curiosity. And my GAL has so many unused outputs. :lol:

Haha ... OK, I get that, cool! :lol:


I can think at least on two good reasons to have 1MB of Ram on the EP:

First, because the amazing SymbOS can manage all that memory.

Yes, that's an excellent reason for those folks that want to maximize SymbOS memory on an Enterprise.


But, there's no Enterprise-specific (i.e. EXOS) software that needs more than 512KB, is there?

Any there many (or any) EXOS programs that need more than 128KB?


And second, because there has always been the challenge of knowing if it would be possible for EXOS to reach the maximum of 4MB of addressable memory that was promised....

Haha ... I can see from your posts that you love to push the Enterprise's hardware expansion as far as it will go. :)

For myself, I am more interested in what I (as a game developer) could have created for the Enterprise if it had been popular enough that I had been told to write a game for it.

So that means that I am focusing on the unexpanded Enterprise 128, and possibly the 6MHz/320KB that were shown in the 911 prototype.
Title: Re: Internal memory expansion
Post by: elmer on 2020.October.14. 06:07:15
Now I can open it up and have a go at doing the internal upgrades, and so test if the new memory board design actually works. :)

Finally ...

[attach=1]

[attach=2]

[attach=3]

[attach=4]

Yes, it works! :mrgreen:

The case fits back together easily too, and there are no problems with the EXP1 cable.


But unfortunely, now I can't figure out how to get the flimsy mylar keyboard connectors back inside the sockets on the motherboard, and so I have no way to run the Advanced test on the memory ... or do anything else at all.

Does anyone have any tips on how to get those connectors into the sockets?
Title: Re: Internal memory expansion
Post by: gflorez on 2020.October.14. 08:40:09
You must grip a strip with the two hands, two fingers each(thumb and index), very near of the tip. Then position the strip on its place and press down firmly on the connector.

The clue is to take a very short portion of the strip, so it not bends while inserting it.
Title: Re: Internal memory expansion
Post by: geco on 2020.October.14. 08:41:46
Looks coll :)
Do you mean the thin keyboard foil back into the connector?
I did it years ago some times, and i took the foil to the top of the connector, and gently pushed down by hand millimeter by millimeter, my fingers were as close to the connector as possible always.
Title: Re: Internal memory expansion
Post by: Wolfgang on 2020.October.14. 12:39:35


Yes, it works! :mrgreen:

The case fits back together easily too, and there are no problems with the EXP1 cable.


But unfortunely, now I can't figure out how to get the flimsy mylar keyboard connectors back inside the sockets on the motherboard, and so I have no way to run the Advanced test on the memory ... or do anything else at all.

Does anyone have any tips on how to get those connectors into the sockets?
Great! :smt038

It seems that there are at least two versions of the original mylar.
One version has two equally long connectors.
The other version has a short left side connector and a long right side connector. Those are a *bitch* to get in. I always ask my wife (she loves me for this :smt074 ) to hold on to the top of the computer while, I use my most surgical hands to do the operation. :smt027

Get a new mylar. They are way better!
Title: Re: Internal memory expansion
Post by: gflorez on 2020.October.14. 16:50:45
Somebody has cut that strip.

Just the point gets crackled on time, and a way to recover the membrane is to cut some millimetres.
Title: Re: Internal memory expansion
Post by: Wolfgang on 2020.October.14. 17:17:10
Somebody has cut that strip.

Just the point gets crackled on time, and a way to recover the membrane is to cut some millimetres.

Yes, but it seems this was already done in the factory. I found this to be the case with two out of three unopened EPs.:(
Title: Re: Internal memory expansion
Post by: elmer on 2020.October.15. 22:40:05
You must grip a strip with the two hands, two fingers each(thumb and index), very near of the tip. Then position the strip on its place and press down firmly on the connector.
I did it years ago some times, and i took the foil to the top of the connector, and gently pushed down by hand millimeter by millimeter, my fingers were as close to the connector as possible always.

Thank you both for the help, I managed to get the cable inserted, and the keyboard works again! :ds_icon_cheesygrin:


Get a new mylar. They are way better!

Yes, that sounds like a very good idea!


But unfortunely, now I can't figure out how to get the flimsy mylar keyboard connectors back inside the sockets on the motherboard, and so I have no way to run the Advanced test on the memory ... or do anything else at all.

I have now run the "Advanced" test in EXOS 2.4, and can confirm that the board design is working properly.

The 512KB of SRAM shows up as expected in banks $C0-$C3, $C8-$CB, $D0-$D3, $D8-$DB, $E0-$E3, $E8-$EB, $F0-$F3 and $F8-$FB.


I have another 8 spare memory boards available if anyone wants one, and it looks like 1 of those is already committed.

There are a couple of points for anyone to consider ...

1) I live in the USA, and international shipping from here to Europe costs more than the board itself.

2) Since this is a self-assembly project that requires soldering, I really can't provide any warranty on the boards ... you would take the same risk of a manufacturing failure (unlikely), or a user-installation error (way more likely) that I did.

Anyway, you really don't want me to solder the headers onto each board to test it ... my soldering skills are pretty terrible these days, and I did a very messy job on the board that I installed in my own EP64.


On the positive side, because I am just trying to recoup the cost for parts and manufacturing, each 512KB board (including all of the headers and the cable for EXP1 and EXP2) is pretty cheap ... $12.50 USD (approx 3,900 HUF) + postage and packing.


Is anyone interested?
Title: Re: Internal memory expansion
Post by: geco on 2020.October.16. 08:06:13
I would be interest for one in case if remains, i do not want to stole the opportunity from others who really need the expansion.
Title: Re: Internal memory expansion
Post by: emptiness on 2020.October.16. 08:48:15
The 512KB of SRAM shows up as expected in banks $C0-$C3, $C8-$CB, $D0-$D3, $D8-$DB, $E0-$E3, $E8-$EB, $F0-$F3 and $F8-$FB.

Nice!

I have another 8 spare memory boards available if anyone wants one, and it looks like 1 of those is already committed.

I would definitely be interested in one. Are these the bare boards or are the surface mount components attached? My soldering skills are probably not up to soldering surface mount components.

Title: Re: Internal memory expansion
Post by: emptiness on 2020.October.16. 08:50:28
And second, because there has always been the challenge of knowing if it would be possible for EXOS to reach the maximum of 4MB of addressable memory that was promised....

It would be very cool to see an Enterprise with the full 4Mb.  I still need to get my Enterprise motherboard working and wired up with a keyboard, maybe a project for after that...
Title: Re: Internal memory expansion
Post by: Wolfgang on 2020.October.16. 10:00:45
The 512KB of SRAM shows up as expected in banks $C0-$C3, $C8-$CB, $D0-$D3, $D8-$DB, $E0-$E3, $E8-$EB, $F0-$F3 and $F8-$FB.

My board is currently using: 
first chip: $DC-$DF, $E0-$EF and $F0-$FB 
the optional 2nd chip:  $BC-$BF, $C0-$CF, $D0-$DB
I tried to create contiguous memory. Is this the wrong approach and should I change the address range?
Title: Re: Internal memory expansion
Post by: geco on 2020.October.16. 10:10:22
My board is currently using:  
first chip: $DC-$DF, $E0-$EF and $F0-$FB  
the optional 2nd chip:  $BC-$BF, $C0-$CF, $D0-$DB
I tried to create contiguous memory. Is this the wrong approach and should I change the address range?
I think contiguous range is the best way, as i remember i worked with at least 1 program which searches the biggest contiguous memory ranges for use.
Title: Re: Internal memory expansion
Post by: pear on 2020.October.16. 10:13:23
The ROM programs should be in banks with numbers x0-x3 hex.
It's good to leave room for them.
Title: Re: Internal memory expansion
Post by: gflorez on 2020.October.16. 10:42:31
It would be very cool to see an Enterprise with the full 4Mb.  I still need to get my Enterprise motherboard working and wired up with a keyboard, maybe a project for after that...

It can be done, I have filled every single segment with Ram/Rom with the aid of the SymbiFace3 board. Amazingly, the system behaves the same as on a 128KB model, total stability.

.....But, there's no Enterprise-specific (i.e. EXOS) software that needs more than 512KB, is there?

Any there many (or any) EXOS programs that need more than 128KB?

On classic times coders took the 128KB Enterprise as an standard, and a lot of them didn't follow the official recommendations when programming. Then you find how some old programs take all available memory for its task(even on an 1MB or more, on an expanded EP) and don't release it at exit.... This is not a problem if you switch ON/OFF every time you run a program, but the Enterprise was created as a multi-session computer, even there are some tasks that can be stopped while doing others.

Other programs take the Ram without asking EXOS or use forbidden memory zones, making the system crash when the control is returned.

It has been only on actual times(quite some years now...) that Zozo has impulsed a standardization on programming, returning to the old official rules, what, added to his modified/fixed EXOS Roms, has brought us a more usable and enjoyable computer.

The previous chaos explains why there are only a few programs that can really benefit from more memory. But don't forget EXOS as the main beneficiary of more memory, because a lot of extensions can be loaded on Ram, better and bigger Ram Disks can be created, Roms can be emulated, etc.
Title: Re: Internal memory expansion
Post by: elmer on 2020.October.16. 18:08:08
I would be interest for one in case if remains, i do not want to stole the opportunity from others who really need the expansion.

It looks like over 30 EP64's have been sold by the Egyptian sellers on eBay recently, but I can't see anywhere near that many new users here.

I'll put you down for one of the boards! :)

Once I've sold my spares, I'll release the design files and final JLCPCB manufacturer-approved Gerbers so that anyone can place another order for more ... they were an easy company to deal with and their board quality and SMT manufacturing seems excellent (to me), and very affordable.


Are these the bare boards or are the surface mount components attached? My soldering skills are probably not up to soldering surface mount components.

The surface mount (SMT) compnents were all factory (i.e. robot) installed by the board manufacturer ... that is why I wanted to create a simple single-sided board design. I certainly couldn't solder those small components myself either!  ;)

The two 0.1" headers male headers for EXP1 and EXP2 do still need to be soldered onto each SRAM board by the purchaser.

[attach=1]


I tried to create contiguous memory. Is this the wrong approach and should I change the address range?
I think contiguous range is the best way, as i remember i worked with at least 1 program which searches the biggest contiguous memory ranges for use.

Keeping the memory contiguous might be the best for anyone that wants to maximize their Enterprise with external modules ... but what I have done doesn't seem like it would cause a problem in practice with any of the expansion hardware designs that currently exist (including the Symbiface3).


The simple 74HCT138 decoding scheme that I have used can fit up to 2.5MB of RAM into the Enterprise's address space, with 2MB of that being contiguous.

Using a GAL/CPLD/FPGA for decoding definitely allows more flexibility, but I think that it is worth pointing out that the Enterprise's designers expected discontiguous blocks of 64KB RAM memory ... the original external 64KB expansion module (http://enterprise.iko.hu/schematics/Enterprise-64k-External-Mem-Expansion-1.jpg) was mapped into one of six different 512k regions of address space, resulting in a maximum of 384KB+128KB of RAM on a fully-expanded Enterprise.


Now, it might not be too difficult to extend what I have done and make a 1.5MB internal RAM expansion board, which could then use an external Symbiface3 to give a full 4MB of memory (3.5MB RAM and 0.5MB ROM) ... but how many people would really want such a board?
Title: Re: Internal memory expansion
Post by: geco on 2020.October.17. 17:56:37
Thank you very much :-)
I created full 4mb  RAM config with sf3 for testing purpose, only 128 KB was ROM, worked without problem :-) , but memory test took quite long even with fast RAM test too, i think 512 kb RAM is enough nearly in all cases, as i remember 1 or 2 programs using the advantages of more RAM, but with SD card interface it does not matter, because both of them loads the whole program into memory if there is enough free memory.
Smaller portions of ranges can limit only 2 programs if i remember well.
The most important in all approach to include F8-FB segments nto the expansion, by this solution all non EXOS compatible programs will work too.
Title: Re: Internal memory expansion
Post by: emptiness on 2020.October.17. 19:53:45
The surface mount (SMT) compnents were all factory (i.e. robot) installed by the board manufacturer ... that is why I wanted to create a simple single-sided board design. I certainly couldn't solder those small components myself either!  ;)

The two 0.1" headers male headers for EXP1 and EXP2 do still need to be soldered onto each SRAM board by the purchaser.

Excellent! Please sign me up for one. I've no problem soldering non-SMT stuff.

Now, it might not be too difficult to extend what I have done and make a 1.5MB internal RAM expansion board, which could then use an external Symbiface3 to give a full 4MB of memory (3.5MB RAM and 0.5MB ROM) ... but how many people would really want such a board?

Hmmmm :ds_icon_cheesygrin:
Title: Re: Internal memory expansion
Post by: emptiness on 2020.October.17. 19:56:23
the Enterprise was created as a multi-session computer, even there are some tasks that can be stopped while doing others.

The more I learn about the Enterprise the more impressed I become. The hardware and solftware feel in a different league from the likes of the ZX Spectrum (the computer I grew up with).
Title: Re: Internal memory expansion
Post by: gflorez on 2020.October.18. 01:23:08
I don't only want to throw words as true: on the emulator or on the real machine, if you have a SD cartridge or a floppy controller you can try this:

-Write a one program line, for example 10 REM.
-Execute LIST to see you program list....
-Execute :EXDOS . This will open you an EXDOS screen where you can for example do a DIR.
-Press the ESC key. The EP will freeze, but if you press once the reset key you are again on Basic.
-Execute LIST.

You can also do the same with the included word processor:
-Execute :WP on the Basic editor. This will open the word processor.
-Write some random text
-Press F8 and execute EXDOS+Enter
-Again the EXDOS screen will open. Make a DIR.
-Press the ESC key. This time the EP has not freezed, and you have returned safely to the text edition.

---------------

Basic itself is multisession, you can edit several programs at the same time, even jump between them while on execution.

-Write this program:
10 TEXT
20 CHAIN 1
-Execute this command: CHAIN 1
-Insert these lines:
10 print "HELLO"
20 CHAIN 0
-Execute this command: CHAIN 0

-You now see a flashing HELLO.

The CHAIN command not only swaps programs, also executes them.

-------

Another proof that the EP is multisession: almost all programs and some games have a clean exit to EXOS:

-Basic has the ":"
-WP has the F8 key
-EXDOS has its prompt.
-Try to search the exit on other languages or utilities, like Hisoft-Pascal, Lisp, Forth, Epdos, EGI, PaintBox, IS-Chess, etc

--------

The main tool to make this possible is an efficient management of memory. Every program will ask EXOS the necessary amount of memory, and at exit they have to free it, returning the memory to EXOS.
Title: Re: Internal memory expansion
Post by: BruceTanner on 2020.October.18. 09:54:41
-Write a one program line, for example 10 REM.
-Execute LIST to see you program list....
-Execute :EXDOS . This will open you a EXDOS screen where you can for example do a DIR.
-Press the ESC key. The EP will freeze, but if you press once the reset key you are again on Basic.
-Execute LIST.
It hasn't actually frozen, but it has failed to restore the text screen correctly. If you type (blind) TEXT 40 it will reset the screen without rebooting. I think this is a bug in EXDOS :oops:
Title: Re: Internal memory expansion
Post by: gflorez on 2020.October.18. 11:38:03
Ah, yes... I have only repeated what you pointed some time ago.... but I didn't remember about executing TEXT blindly.

Thanks.
Title: Re: Internal memory expansion
Post by: dangerman on 2020.October.19. 22:31:15
If you type (blind) TEXT 40 it will reset the screen without rebooting.

To avoid blind typing, by default you can press F5 for "TEXT" or even SHIFT F5  which will redisplay an existing text screen.

I think this is a bug in EXDOS :oops:

I'm not sure it's a bug as such. EXDOS has no easy way of knowing what was previously displayed.
Title: Re: Internal memory expansion
Post by: Judge on 2020.December.02. 20:27:34
It looks like over 30 EP64's have been sold by the Egyptian sellers on eBay recently, but I can't see anywhere near that many new users here.

I'll put you down for one of the boards! :)

Once I've sold my spares, I'll release the design files and final JLCPCB manufacturer-approved Gerbers so that anyone can place another order for more ... they were an easy company to deal with and their board quality and SMT manufacturing seems excellent (to me), and very affordable.


The surface mount (SMT) compnents were all factory (i.e. robot) installed by the board manufacturer ... that is why I wanted to create a simple single-sided board design. I certainly couldn't solder those small components myself either!  ;)

The two 0.1" headers male headers for EXP1 and EXP2 do still need to be soldered onto each SRAM board by the purchaser.


Thanks, John!

[attach=1]

[attach=2]
Title: Re: Internal memory expansion
Post by: elmer on 2020.December.02. 20:37:26
Thanks, John!

Excellent, I'm so glad that you had no problems installing the board, and it's good to see it working on some else's computer! :ds_icon_cheesygrin:

Your soldering skills look so much better than my old hands and eyes were capable of doing! ;-)
Title: Re: Internal memory expansion
Post by: elmer on 2021.January.12. 17:41:15
I only have 2 of the 512KB memory expansion boards left, if there is anyone else out that that wants to add some memory to the Enterprise 64 that they recently bought from Egypt or Russia. ;-)

(https://enterpriseforever.com/index.php?action=dlattach;topic=891.0;attach=25631;image)
Title: Re: Internal memory expansion
Post by: elmer on 2021.February.18. 18:32:56
I only have one 512KB memory expansion board available if anyone wants it! ;-)

Here are my memory board design files for EasyEDA (https://easyeda.com/), together with the Gerber files and production order files for anyone that wants to get another batch of boards manufactured at JLCPCB (https://jlcpcb.com/).

I have also included the final "Production" files that I got back from JLCPCB, which have the "Tooling Holes" that JLCPCB added so that they could manufacture the boards.

The only strange thing in the process was that I had to edit the "PickAndPlace" file to rotate the SRAM chip 90 degrees, because EasyEDA had output the file with the wrong orientation.  This was only visible when I uploaded the files to their website, and then looked at rendering of the board before finally confirming the order.
Title: Re: Internal memory expansion
Post by: gflorez on 2021.February.18. 20:23:31
Great!

Thanks for being so kindly sharing your work.
Title: Re: Internal memory expansion
Post by: elmer on 2021.February.18. 21:33:59
Great!

Here's a design that you might find even more interesting! ;-)

After I had confirmed that the 512KB board was working, I decided to see if I had learned enough about EasyEDA to expand it into a larger board.

Here's the design for a 1.5MB SRAM board. :cool:

I don't plan on actually making any of these for myself, because I think that I may have come up with an idea that better fits my needs, but someone else here might be interested in this.
Title: Re: Internal memory expansion
Post by: kokkiklhs on 2021.March.03. 11:28:46
Thank you, Elmer!
This is really fantastic!!!