RE: [techtoolslist] 6800 -> 6502 fluke pod conversion

ok, had a squint at the 6502 pod schematics and noted down the jumper
differences. not too many differences, it *may* be possible to knock up a
GAL to allow you to have a single switch to alternate, but you'd still need
to replace the CPU each time.

basically, unless I mucked up somewhere ...

[W1 and W2]
now someone with real schematics may want to check this, it's not too clear.
it looks like it's picking up clock 02, buffers it and uses it to drive
things.
6502 = pin 39 (02 out)
6800 = pin 37 (02 in)

[W3 and W4]
eprom pin 19 : 6502 = GND, 6800 = 5v (two images in same rom)

[W7,W8 and W9]
changes what pin 39 is used for
6502 = ouputs signal through a buffer to BTSC signal (02)
6800 = inputs BTSC signal, AND's with ENABLE (TSC)

BTSC is labelled as '02 out' on schematics elsewhere, just seems odd to
change it to an input for 6800!

[W11 and W12]
6502 = connects pin 5 to VMA signal
6800 = connects VMA signal to 5v

[W14]
6502 : test socket pin 3 open
6800 : test socket pin 3 to reverse of clock to pin 37 (uses reverse output
of 7474)

[W16]
6502 : test socket pin 39 open
6800 : test socket pin 39 to 5v

so, whether a 6800 old style can be changed depends upon some signals
existing (is VMA implemented in any way, since it's tied high for 6800)

so, next on the agenda to look at the 6800 circuit, and see if the necessary
control lines exist.
Received on Wed Sep 10 16:55:20 2003