From: Hársfalvi Levente (levente_at_terrasoft.hu)
Date: 2003-09-22 18:53:48
Hi!,
> Hmmm, I thought more of expanding it to a full 64 KB RAM (or whatever
> is possible) ...
It's simple (or better said, a question of some practical skills and a good
soldering iron). I expanded a few C16s like below.
- Replace the two 4415 RAMs by 4464 chips (you can find schematics on Funet,
http://www.funet.fi/pub/cbm/schematics/computers/plus4 , see c16* )
- Cut the PCB route going to PIN 2 of U7 (74LS257)
- Cut the PCB route going to PIN 14 of U8 (74LS257)
(These were connected to +5v)
Now find A14 and solder it to P2/U7 by a wire. Find A15 and connect it
similarly to P14/U8. You can find the above two signals somewhere at the
PCB; for example, you can get it from P37 and P36 of the TED, or from the
expansion port, or the FPLA... (see the schematic diagrams).
Expanding the computer by an external module would probably be a wiser
decision (no hacking inside the computer), but I have no idea how that
circuit should look like :-(.
Best regards,
L.
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