Damn, I should have thought of that! :oops::-)
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.
With some more ICs can do the trick to decode for DC to FB.I'll have a think about that! :)
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:
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!
You can probably use your eprom programmer to program the PAL.
Very Nice.......Yeah, I had a quick look at the schematics for the spectrum emulator last night as bedtime reading... :)
I agree with Zozo that it would be good to see if the Spectrum Emulator can be
addressed in the same way.....
Russ
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!
I've ordered a batch of 10 pcb's now, for the bargain price of under £10.Where you order?
Where you order?I would be interested to know that too!
I'm glad I went 'old school' and used all through hole components for the EP memory expansion. :DGood idea!
My PCB's arrived today! Looking good.Nice!
My PCB's arrived today! Looking good.Two tracks between pads - you'd never do that by hand!
This is the motherboard.Nice!
I now need to install Zozo's EXOS with fast memory checking!Good idea! :-)
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?
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.
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!
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!
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.
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 :-)
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.
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:Complete Z80 replace less than 10 minutes :-D
It's nice to think I'm helping keep the Enterprise alive! :)Thanks for the effort that you are putting in - It is appreciated.
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... :)
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!
all boards tested perfectly with advanced testGreat!
new batch of 10 PCB's ordered!When do you think the second batch available?
When do you think the second batch available?
Current orders from Hungary: 8!
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... :(
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.
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 ...
So what can be more cool than this internal 512KB expansion is a 1MB or 2MB internal expansion ... :)
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... :)
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!
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.
Can I ask where (and how) you order those GALs (and maybe the SRAM) exactly? Or is it some kind of "secret source"? :)
So in this case one of the "hungarian" boards could be 1MB.
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?
The 1M version can be chosen? It is a +5 GBP?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.
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.
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 )
so I don't think it should be a problem.
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.
The SRAM is actually 55nsI hope it is will be enought fast for 10MHz Z80!
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.
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!
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.
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.
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
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. :)
@SaintI'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:
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
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.
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.
My newly installed memory expansion (and EXOS 2.4beta) is working perfectly:ds_icon_cheesygrin:Great stuff! Glad to hear another is working... :smt041
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... :smt041Last 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.
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:
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?
Currently: 8x1M, 4x512K, another one waiting for answer.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.
Do you want some money prepaid? (For buying components.)
Today im very happy my precious Enterprise have 589kb memmory and working without problem :ds_icon_cheesygrin:Great stuff! :mrgreen:
THANKS !!!!!!!! JAMES!!!!!!!
Currently for Hungary: 8x1M, 5x512KThanks 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!!
Still waiting for pcb's and GAL's... :(Change possibly...? We may live in hopes? :-)
I have 20 GALs now. I will get on and finish the boards in the coming days... :DYeeeeaaah! :-)
Unfortunately the HUF got a very bad exchange rates at current days :evil: :cry: :(
Another 2x1MB finished and tested. Remaining 4x512KB finished, waiting for more SRAM (here in a couple of days).Thx! :-) Great! :smt041
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...
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 :-)
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.
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?
Boxed and ready... :)Great! :ds_icon_cheesygrin:
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:
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.
Hope this is useful... :)Thanks!
Boxed and ready... :)Arrived! :ds_icon_cheesygrin:
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:
First one installed to Szalai56 machine :ds_icon_cheesygrin:Awesome! Great to see my little boards getting fitted... :ds_icon_cheesygrin:
If a game would load all of the one megabyte,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.
for what time would it load ?
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 :-)
If a game would load all of the one megabyte,Using tape it would take ages. :D
for what time would it load ?
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 ?
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.
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 ...
but the sound will be almost broken ...Not broken just different. Sometimes very funny :-) You can easy try it in a emulator.
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 ;)
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?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)
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)It is ok! Thanks! I will try it :-)
Total 3264K used of the 4096K address space (http://enterpriseforever.com/Smileys/phpbb/ds_icon_smile.gif)Fck yeah ! :)
Zozo says he has re-modified further his Microteam, not the gal....The new GAL program also needed!
I think the emulator now needs to be adapted to 640k of posible ROM.It is can be done by epmemcfg.exe.
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.
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)
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
The DuPont connector was the supplier I ordered from,After 1 month wait I got the DuPont cables. Others got from local store :-)
1MB version also available?Yes, the new PCB's make it a bit easier to do the 1MB board as well.
Hello,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 ?
Is there someone out there who would do this job for me?Done :ds_icon_cheesygrin:
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.
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 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 :)
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 :)
It is equal, EP64 slower only, because everything is used from VRAM
both versions are in the picture, the new is the red PCB
thoughtful version in small and flat size
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 ?
Here is the explanation :)
The same functions with the same wiring, only in SMDWiring not same :-(
It is annoying....Yes. But existing "Saint cables" can be modified to universal with cutted dupont headers.
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.
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 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 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.
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).
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.
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.
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.
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.
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.
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.
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)?
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.
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)
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.
The order of the threads is changeable.
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).
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.
I have already asked him by mail. I am waiting an answer.
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.
Wow - great work! :smt041
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?
Not worrying about the order of the address and data lines makes life much easier doesn't it?
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.
Great decision to put a FlashRom.
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.
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.
Excellent work. :smt041
Btw, what program did you use to do the design?
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.
Cool, what's the minimum order quantity?
I'd definitely be interested
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.
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.
Unfortunately, I was too optimistic about EXP2. I can close the top, but it bends the plastic out about 1mm.
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 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?
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?
Unfortunately, I was too optimistic about EXP2. I can close the top, but it bends the plastic out about 1mm.
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.
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.
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?
Now I am really nervous if this is going to work at all. :roll:
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)!
Then the cable works well.I am very pleased. :smt026
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! ;)
My pcbs arrived today:
and everything seems to work okay. :)
If I knew the scart connector was good for you, I would have soldered it. Sorry! :oops:
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.
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! :)
For no sensible reason, just intellectual curiosity. And my GAL has so many unused outputs. :lol:
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:
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....
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. :)
Great! :smt038
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?
Somebody has cut that strip.
Just the point gets crackled on time, and a way to recover the membrane is to cut some millimetres.
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.
Get a new mylar. They are way better!
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.
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.
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....
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: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.
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?
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...
.....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?
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.
Are these the bare boards or are the surface mount components attached? My soldering skills are probably not up to soldering surface mount components.
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.
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.
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?
the Enterprise was created as a multi-session computer, even there are some tasks that can be stopped while doing others.
-Write a one program line, for example 10 REM.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:
-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.
If you type (blind) TEXT 40 it will reset the screen without rebooting.
I think this is a bug in EXDOS :oops:
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!
Great!
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.
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/).