Wednesday, 20 July 2016

I got a MAX machine - but with dead 6566 :(

I got a Max machine from a seller in tokyo in unknown condition for a fair (not cheap) price.
After checking the hardware I found the problem: The 6566 is dead - it doesn't divide the dotclock by 8.
I tried a 6567 on a breadboard as divider - and the machine runs (without picture).

Now I designed a 6566 replacement with a 6567:

- 74373 to isolate the A0 to A5 outputs with RAS
- 74373 to isolate A12 and A13 with CAS
- 74245 to tristate the A0 to A5 inputs in the VIC
- 7404 to invert AEC for the 245

I build this on a breadboard:

...and it works ;)

Now it's time to design a layout for an 6566/6567 adapter that fits in the 6566 socket.