Hello,
After building several Apple 1 and Apple II replicas, I had the crazy idea of building a Lisa replica from scratch.
Gerber PCBs are available, board production is not cheap, but you only live once :) I have all the parts needed for the build, except for the COP421.
Precisely. I have new (10pcs) COP421 DIP28, but I don't know how to program them? Does anyone have any ideas on how to program these chips? The BIN is available.
An alternative is to use this COP402/404 to COP421 adapter ( http://john.ccac.rwth-aachen.de:8000/patrick/COPSreader.htm ), but ironically - I can't get a COP402/404 anywhere.
HELP:)
Mateusz SQ9PXB
You cannot program a COP421 microcontroller. It seems to have a mask ROM, which means it can only be programmed during fabrication.
If you have the BIN file, you need to use an "emulator" like this one, which is basically a COP400 family microcontroller that works with an external PROM chip. You can find the COP402MCPN chip on eBay: https://www.ebay.com/itm/225424422717
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Hi,
Thanks for your reply. Studying the factory documentation, I'm not sure what it looked like in the 1980s. The most interesting thing is that my local vendor has new COP421L-JRL-N chips. But so what? It has to be programmable somehow....
Buying a COP402 from eBay from the US is a problem – very high shipping and customs costs per unit.
In my opinion, the optimal solution would be to replace the COPxxx with a modern PIC/AVR-style uC. You'd need to know exactly what commands the original COP421 transmitted to remap it.
Regards,Mateusz SQ9PXB
In the early 80s to program a COP400 family microcontroller you would get a COP400 Product Development System. It contained a ROM-less COP chip and some PROM sockets. You would use it to write and debug your code and when you are done you would send the ROM to National. They would produce for you thousands of COP chips with masked ROM containing your code. Some of these preprogrammed chips will be left unused, survive until the present day and be sold as NOS to unsuspecting customers.
COPSDevSystem.png
Source: https://seanriddle.com/NSC_COP400PDS_Users_Manual.pdf
What caught me off guard was that the store had a large number of COP421s. So I wonder what's in their ROMs :)
Unfortunately, it turns out that getting a COP402 for the adapter will be my biggest challenge with this project...
I hope so.
Regards,
Mateusz SQ9PXB
Here is another listing from China. Higher price than the one from the US, but the shipping to Poland is very cheap. Looks like it's the same seller with two different accounts. He accepts offers, so you can ask him to match the price of the other listing: https://www.ebay.com/itm/315553382173
Yes, I saw that Chinese ad, but it seemed suspicious to me. There are identical photos in another ad from a US store. I'm worried the Chinese seller might be a scammer.
BUT
I just bought the Soviet equivalent of the COP402 -KR1820VE1A, from a Lithuanian store for only 1.50 euros. Unfortunately, only one pcs was available. I hope this works.
https://www.evita.lt/en/m-1820ve1a-kr-microcircuit-kr1820ve1a?search=KR1820VE1A
Regards,
Mateusz SQ9PXB
Very nice! I love using Soviet and other Eastern bloc alternatives myself. They are super cheap, available in huge quantities and no one fakes them. With Soviet ones just be sure to use slotted sockets instead of machined ones, because they are metric and do not align perfectly.
Personally, I use Soviet chips as a last resort :) But if they're available and there's no alternative, why not? I recently built a manual programmer for KP556PT4A PROM chips (almost equivalent to the 74S287 - OC vs. 3-state). I've run Apple 1 and ACI on these Soviet chips... But that's off-topic.
https://www.youtube.com/watch?v=p6M5ABbfTHk
Regards
I just received the Russian replacement for the COP402, the KP1820BE1A. I hope it works. But there's still a long way to go.
IMG_20260128_161511.jpg
It's not Russian. This is the logo of "Integral" in Minsk.
Thanks for the info, I wasn't familiar with the Belarusian factory.
Out of curiosity, I bought a whole tube of COP421L from my local supplier. The date code is 1983, but the chance of it having a Lisa ROM-Mask is probably like winning the lottery :) But the price is nominal. I'll keep them as decorations.
Regards,
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In case your curiosity gets out of control, there is a project that lets you dump the mask ROM:
http://john.ccac.rwth-aachen.de:8000/patrick/COPSreader.htm
Yes, I know that site. I even cited it in my first post. Maybe someday I'll get around to reading my COP421 :)
This thread is duplicated (https://www.applefritter.com/content/report-assembly-apple-lisa), but it might be useful to someone. Today I bought 16 brand new COP402N chips and I'd be happy to share them with those in need (in Poland. If you're outside Poland, please suggest how to ship them - I'm not an expert on this....). In my (not) workinkg, the Lisa Rreplica behaves exactly like its Soviet counterpart, so I'm 100% sure these chips are functional (but I can't guarantee it, of course).
The COP421L shown above has also been tested and does not work (does not turn on even after soft power on) compared to the COP402N in the adapter board - its works.
Regards,
0.COP402.jpg