exxos's Atari, Amiga & retro forum

Yes, it should be finished during novembre, if all goes well

It took some time to make work the power supply adapter. It turns out the schematic had wrong values on some resistors that are part of the feedback loop around the LM311. With help from knowledgeable people on the french forum, we could assert the correct values. Same thing for the reset circuit, a wrong value (100uF instead of 1uF) gave a long delay (in the 5-10 seconds range).

Plugging a SDDrive extension (disk unit emulator using SD Card ) and a "music and game" extension (2 game controllers and a 6-bit DAC for sound), I could perform some typical activity on this remake, validating that most part of the computer are correct. I won't test the tape reader port nor the light pen port (no CRT anyway) on this assembly. I plan to get a finalized version ( actually a release candidate 2 or 3) and assemble it next spring.

:bravo:

Thanks, and here is the final timelapse :

It's a wonderful work it's very difficult to do this kind of job most of the time the published schematics are not accurate...
for example the commodore schematics if the many notes and patches are not taken into account it's not working


an interesting step would be one day to have a source of MO5 Asic perhaps a rebuild in a CPLD ?
I checked in the past but I never found any clear information on this chip

6502addict wrote: 30 Jan 2025 19:19 an interesting step would be one day to have a source of MO5 Asic perhaps a rebuild in a CPLD ?
I checked in the past but I never found any clear information on this chip

The gate array has already been reversed in VHDL by a two people, "Fool-DupleX" and "Whitebird". I plan to have a go at it later.

For the other custom chip, a PROM of 32 bytes that transcode pixel color into RGB-222, I have just done a substitute using a GAL16v8 : https://github.com/sporniket/kicad-conv ... eplacement


And to get the PROM data and check the result afterward, I made a little testbench with an Arduino.

6502addict wrote: 30 Jan 2025 19:19 It's a wonderful work it's very difficult to do this kind of job most of the time the published schematics are not accurate...
for example the commodore schematics if the many notes and patches are not taken into account it's not working

That's why I "proof-read" the schematic by reproducing an actual motherboard.

yes it works well, a friend Meridian was playing with a thaler 6502 the decoding was done by a prom
he asked me if I had a solution... in his case it was easy it was possible to map the prom bit to the gal pin
almost exactly I only had to build an adapter to connect VCC and GND

http://retro.hansotten.nl/uploads/files ... GAL-EF.pdf

if one day you are stuck with a prom I can help you
I have a dataman 48 pro 2 it can program old chips PROM / PLA / hight tension eprom
till know I find my PROM / PLA from utsource.net but there is a problem the sell "USED" or "NEW" chip
we have to be sure that we are buying "NEW" chips when we buy some PROM or PLA

for the ASIC due to the number of pins it is probably necessary to use an EPM7128S or EPM7160S
altera / intel CPLD require a GND and a VCC by side + 4 pins for JTAG

I'm thinking to rebuild the MO5 in VHDL (I have 80%) of the element but I will reproduce the memory map not the asic itself

6502addict wrote: 31 Jan 2025 10:32 I'm thinking to rebuild the MO5 in VHDL (I have 80%) of the element but I will reproduce the memory map not the asic itself

I see, have fun.

In fact it's only a variation on the SWTPC I already rebuilt on a DE10 lite
the difference is the graphic board not on the SWTPC but I already have it from
my CBM 8032 video signal to VGA converter....

the problem is the implementation of the lightpen... I guess the best idea is to replace the lightpen by a mouse
and return le location of the cursor...

problem... probably no way to use Daniel's floppy interface (timing problems)

actually I'm gathering the ressources...
precise memory map, rom image, floppy rom image...