Are there any CPC mainboard Gerbers, or Eagle, Kicad, Proteus, Altium

Started by jb2590, 00:51, 25 August 21

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jb2590

Hello All, I live in United States and unfortunately we dont have the Amstrad CPC easily available here. Based on Verilog code posted by @gerald , @DaDMaN , and others , I was able to write the 40010 gate array code to a Spartan6 FPGA. I don't have a CPC to test with so I am looking for a board file so I can build up a system to test the new FPGA 40010. The cost of A used CPC on ebay and shipping from Europe is around $200 USD usually for an untested parts machine.

Thanks for any help in finding a board file, or any other ideas.

John

GUNHED

Yes, CPCs in USA are a rare good. (For 8,5 years I lived in NOLA).
And users are few. Get in contact with this CPC user, he lives in the USA too and may be of help:
https://www.youtube.com/channel/UC1dEZ22WoacesGdSWdVqfTw/videos
http://futureos.de --> Get the revolutionary FutureOS (Update: 2022.03.09)
http://futureos.cpc-live.com/files/LambdaSpeak_RSX_by_TFM.zip --> Get the RSX-ROM for LambdaSpeak :-) (Updated: 2021.12.26)

jb2590

Thanks @GUNHED I sent him an email. Hopefully I am able to find a mainboard file. I could spend hours going over the schematic and transcribing it into Eagle, but I am worried I will introduce too many points of failure with an untested eagle design and untested FPGA. It would be a lot of trouble trying to learn what is actually causing problems when it doesn't work.

GUNHED

Maybe @TotO could help too, he did awesome hardware for the CPC.  :) :) :)
http://futureos.de --> Get the revolutionary FutureOS (Update: 2022.03.09)
http://futureos.cpc-live.com/files/LambdaSpeak_RSX_by_TFM.zip --> Get the RSX-ROM for LambdaSpeak :-) (Updated: 2021.12.26)

TotO

Hello and welcome,

If you want to build a CPC mainboard, you can put first all the real parts on it.
Next, to remove the gate array and interface your FPGA instead.

You will have to add a keyboard, a tape or floppy drive equivalent to run programs too.
I'm pretty sure that is more effort and time than buying a CPC for your main project.

A picture posted by gerald six month ago about his GateArray replacement:



Now, I can imagine the Spartan6 FPGA can replace the PAL, CRTC and the main RAM too.
So, what is the real goal? Doing something like a CPC Next?


"You make one mistake in your life and the internet will never let you live it down" (Keith Goodyer)

stevensixkiller

There seem to be a kicad file but for the aleste520x, a 1993 6128 clone. I don't know if it's 100% compatible with the real original:https://www.cpcwiki.eu/forum/amstrad-cpc-hardware/aleste-520ex/
https://github.com/LasDesu/Aleste-520EX/tree/master/sch

jb2590

Hello @TotO

I am really just looking for a good hobby project. I have wanted to build out my own 8 bit micro with modern or easily obtainable parts while trying to stay as true to the original hardware as possible. First I would need to change the design in some ways to make it easier to use, like a external keyboard connector. Then once i get something up and running  I could iterate through various designs to add extra capability. I was hopeful that there was a PCB file available somewhere I could use as a starting point.

I think the best way forward if there are no current board files available is to just buy a used CPC. Using that I can build out a working GateArray replacement. Then I can begin laying out a board design around the GA replacement and iterating through design changes to build my own 8-bit Micro.

I don't really want to just run everything in FPGA, otherwise I would just build out a ZXUno4ALL or some other similar FPGA system replacement and just load whatever core I wanted.

Do you know if @gerald released any files for his replacement? I was successful in writing the Verilog code he posted onto my Spartan6 dev board, so after adding some level shifting and testing on real hardware, hopefully I can get a working GateArray to build my computer around.

Thanks,
John

TotO

Helo @jb2590 ,

Some peoples have already done their own custom CPC mainboards. From my side, I have not reproduced the original CPC design. My schematics are inspired from it, but I have introduced many changes from the begin for my own projects.

When I speak about including the GA, PAL, CRTC into a the FPGA, it is because Amstrad does that for the last CPC release (pre-ASIC). It will allow to dramaticaly reduce the mainboard complexity by removing all the dedicated video buses and keep the interresting Z80 computer design around that (not a one chip computer but a one chip display controller).

It is an interresting way to follow, because it can allow you next to do a custom Amstrad PLUS computer.

  TotO
"You make one mistake in your life and the internet will never let you live it down" (Keith Goodyer)

TotO

May be I can help to start by releasing some parts of the CPC schematics I have redraw with eagle.
"You make one mistake in your life and the internet will never let you live it down" (Keith Goodyer)

Bread80

I have schematics I've transcribed into KiCad, but they're utterly untested. I've also made a few changes, such as upgrading to SRAM.


The SRAM logic means changes to the video data bus and I know that isn't working, based on other tests I've done. I currently have an SRAM plugin board at the printers to test revised ideas for this.


I've also taken the 'combined' KiCad files and split it into separate parts to go into an RC2014 backplane. This will enable me to test the schematics in parts. This project is currently waiting the final revisions to the SRAM circuit.


And I've been working on a gate array replacement using Raspberry Pi RP2040/Picos. Off the back of this I've learnt a tonne of stuff about the gate array signals and timings - some of this is on my article at http://bread80.com/2021/06/03/understanding-the-amstrad-cpc-video-ram-and-gate-array-subsystem/


If any of that is of use to you then I'm happy to share or collaborate.

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