The battle for the System 80 has begun!
I started with no video, no CPU activity, and a very bodgy looking 64k DRAM upgrade using 4164s
Fixed the CPU issue by replacing a dead electrolytic in the reset circuit. Video came back when I replaced the cable between the boards.
I’ve reversed the 4164 upgrade and am working on the Drastik.
The time honoured “ROM of NOP” is generating square waves on the lower 8 address lines. Now I need to find where they stop being square!