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Messages - elmer

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Hardware / Re: Capacitors - wrong orientation?
« on: Yesterday at 04:20 »
I replaced the C9 capacitor on my 64/128 motherboard with a bipolar one. Working perfectly.

Excellent, that is great to see. :)

I am very jealous of that beautifully clean motherboard! ;)

Wanted / Re: EP with working 08-47 Nick
« on: 2020.October.18. 00:26:58 »
Only in games and demos or the little BASIC test program on my TFT

Thank you for that link, it was really helpful to read that thread! :cool:

The differences on the defective Nick are: strange pixel glows on multicolour screens
My revision 4 motherboard with 08-04 Nick doesn't seem to be showing any propblems (yet) on a CRT

OK, now that I know what to look for, I can confirm that my Egyptian EP64 has the problem too! :cry:

It just takes a minute or two for my Nick chip to warm up enough so that the flashing pixels appear.

I can also see the same problem if I run WP 2.6 ... the two text lines at the bottom of the screen start to show pixel flickering after a few minutes when the Nick chip warms up.

Apart from that ... good luck with the hunt!

Well, I guess that now I'm going to be on the hunt for a motherboard/computer with an 08-47 Nick chip as well.

Jeez, I really wish that I hadn't given away my lovely Enterprise 128 when I moved to America! :oops:

In the meantime, does anyone have any hints or tips for removing the heatsink on my Nick chip so that I can try to replace it with a better one?

Wanted / Re: EP with working 08-47 Nick
« on: 2020.October.16. 20:45:31 »
I would like to get a fully working 08-47 Nick without the blinking pixels.:smt022

When do you see blinking pixels, is it on the boot screen, or just within games?

My revision 4 motherboard with 08-04 Nick doesn't seem to be showing any propblems (yet) on a CRT ... are you viewing on a CRT, or upscaling to an LCD?

Apart from that ... good luck with the hunt!

Interface / Re: Internal memory expansion
« 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.


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 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?

Interface / Re: Internal memory expansion
« 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?

Games / Re: Nebulus CPC port
« on: 2020.October.14. 19:41:56 »
Sadly OP Wolf is Speccy port :( Amstrad port with EP enhancements would much bettah :)

Andy and Ivan did a really good job on both those ports, and it was really nice to see scrolling in an Amstrad game!

OTOH, the Amstrad does have simpler background graphics than the Spectrum (probably due to lack of memory).

Either way, you wouldn't likely see much (if any) improvement on the Enterprise, because the game's screen layout doesn't allow it to take easy advantage of the Enterprise's features, and it would take a major rewrite of the game code to change that.

Interface / Re: Internal memory expansion
« 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 ...





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?

Interface / Re: Internal memory expansion
« 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.

Interface / Re: Internal memory expansion
« 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?

Hardware / Re: Capacitors - wrong orientation?
« on: 2020.October.10. 05:13:49 »
Thanks. On my EP it was 6.3V, but of course these are prone to failure and might have been replaced in the past, so it might not have been the original original! :lol:

FYI, I finally opened up my EP64, serial #71370 (so fairly late manufacture), and it also uses 6.3V 100uF capacitors for C9, C11 and C12.

In this case they are all old-style axial, and Unicon brand (another decent-quality Japanese manufacturer).

That is on an issue 4 motherboard, which unfortunately has 300ns video RAM, so I presumably won't be able to change to a 6MHz clock unless I replace those. :(

Interface / Re: Internal memory expansion
« 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.

Interface / Re: Internal memory expansion
« on: 2020.October.10. 04:43:14 »
My pcbs arrived today:
and everything seems to work okay. :)

Congratulations! :mrgreen:

Interface / Re: Internal memory expansion
« 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! ;)

Hardware / Re: Capacitors - wrong orientation?
« on: 2020.October.06. 02:07:34 »
I found it here...

Cool, eBay to the rescue! ;)

It looks like you can get the smaller voltage ones here.

Interface / Re: Internal memory expansion
« 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. :)

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