Monday, February 17, 2014

CoCo 3 Upgrades: Hitachi 6309 CPU, 512KB RAM, PS2 keyboard

Installed a bunch of CoCo 3 upgrades from Cloud-9 Tech over the weekend:

  • I upgraded the old 68B09 CPU to the powerful Hitachi 63C09. This involved desoldering the old CPU and replacing it with a socket. I also put in a Pro-Tector+ board to protect the CPU from the inevitable torture I have planned for this thing (once I get all of my electronics gear out of storage and back in one place).

  • The Cloud-9 512K Triad upgrade board (the blue triangle) was trivial to install by comparison. Following the instructions, I removed the four old (128K) RAM chips, snipped a couple capacitors, and plugged it in:

  • Cloud-9 also sells a nice PS2-keyboard upgrade board which was an easy install (no soldering):

I enabled 6309 native mode (15%+ faster vs. 6809 mode) and tested it with my gcc6809 compiled test program. Here it is outputting text to the 40x24 text mode:

I'm currently scrolling the text screen up using a simple C routine. It's so embarrassingly slow right now (even at 1.89MHz 6309 native mode) that you can kinda see the scroll function move the lines up the screen. But this is fine for simple printf()-style debug output. I'm using this BSD-licensed tiny printf() for embedded applications.

I've also compiled in the DriveWire 4 assembly 115kbps/230kbps I/O routines into this test app, so I can do disk I/O without relying on OS/9 or the BASIC ROM routines. My plan going forward is to continue completely "taking over" the machine and just do my own thing (no OS at all). It should be easy to code up a DriveWire compatible I/O disk module (here's the DriveWire protocol specification).

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