馃嚝馃嚪 Matra Alice: Part 4 (Keyboard Fixed & Internal 8KB RAM Upgrade) [TCE #0578]
29Thanks to #PCBWAY for their continuing support! https://www.pcbway.com/
Check out their Shared Projects - ordering via PCBWAY helps out the creators:
https://www.pcbway.com/project/
I finally got the keyboard working properly - the new-old-stock Motorola 6803 CPUs arrived from Unicorn Electronics today ... I swapped out the original Thomson part and the keyboard started working as expected. Finally!
This meant I could also move on and try out my internal 8KB RAM upgrade daughterboard ... based entirely on Daniel Tufvesson's excellent blog:
https://www.waveguide.se/?article=expanding-the-trs-80-mc-10-internal-ram
Daniel was working on a Tandy TRS-80 MC-10 which has quite snug FCC shielding covering the CPU and RAM chips, so he had to get creative to squeeze a 6264 chip in.
The Matra Alice (and now also my MC-10) has no such problem so I designed a simple daughterboard based on Daniel's work. I had to do a little bit of detective work to figure out how the MC-10's A12 bodge wiring was implemented, but it turned out to be quite a simple change required.
Resulting free memory:
Stock Alice 4KB: 3142 bytes
Alice with 8KB: 7238 bytes
Alice with 4+16KB: 19526 bytes
Alice with 8+16KB: 19526 bytes (hmmm - no change)
I will upload the info to my Github and to PCBWAY's Shared Projects once it's ready:
https://github.com/0ddjob
00:00 ... Intro
01:40 ... CPU replaced
05:15 ... Free memory with 4KB & 20KB RAM
07:30 ... Internal RAM upgrade preparations
10:14 ... Internal 8KB RAM daughterboard
12:57 ... Daughterboard installation
16:08 ... A12 - A13 modification
18:18 ... Testing upgrade
23:00 ... Upgrade details (still images)
23:45 ... Channel thanks & outro
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For the MC-10, A/V mod:
https://hackaday.io/project/182433-mc-10-av-mod-board
https://github.com/Danjovic/MC-10
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From Part 2:
The replacement keyboard screws (M2x6 pan head) finally arrived ... but there are still problems with the keyboard. Some keys don't work at all, some keys do work fine and some others print the whole row of keys.
Oh, and look what I found:
https://github.com/Fred72z/ALICE
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From Part 1:
This boldly red computer is a French version of the Tandy MC-10 using the same Motorola 6803 CPU clocked at 890KHz and using the same MC6847 Video Display Generator (VDG). It was built by French companies Matra and Hachette but seems to be commonly known simply as the "Matra Alice".
The main difference, apart from the bold colour and AZERTY keyboard layout, is the RGB video output (via a 7-pin DIN) rather than RF modulated video ... yay!
The video pinout is:
Pin 1 = n/c
Pin 2 = ground
Pin 3 = red
Pin 4 = synch
Pin 5 = green
Pin 6 = audio
Pin 7 = blue
After building the video cable and supplying 10VDC, I got an image which was quite unstable. I noticed a variable resistor (R45) in the video output stage so gave it a tweak ... perfect, almost! This R45 looks to adjust the level of the FS (field synch) and HS (horizontal synch) signals coming out of the MC6487 VDG, which makes sense why it resolved the stability problem.
The keyboard wasn't working properly ... looks likely due to a mechanical issue ... missing screws! Whilst I have it apart I might as well give the case & key caps a good wash before reassembling with some replacement screws.
Then it'll be time to try loading some cassette software. I'm assuming I'll need the 16KB RAM expansion to play any modern software.
And I'm assuming that it should run Tandy MC-10 software ... although key mapping might be an issue due to the differences in the English QWERTY and French AZERTY layouts ...
I guess this machine could easily be converted to a bog-standard Tandy MC-10 by rearranging the keys and replacing the ROM ... a bright red MC-10 with built-in RGB video output ... but then it'd lose a lot of its charm!
This page (in French) looks to have some quite good information about the Alice series of computers:
https://alice.system-cfg.com/about.php
There were further versions ... this first one (same as the Tandy MC-10) is also known as the "Alice 4KB". The Alice 32 was next with 16KB of RAM and using a different video chip, then the Alice 90 with a proper keyboard & more memory, then finally the Alice 8000 that had both a Motorola 6803 and an Intel 8088.
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https://karlcasey.bandcamp.com/
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