It's time for another 68k Mac repair. I thought it would be a quick and easy fix, but this turned out to be a but more mysterious.

-- Info

Microbug:

DM (dump memory)

SM (set memory)

Video page:

U15D VIA 6522 PA6 Pin 8 to U4G 74AS253 Pin 4

From microbug, I was writing to

3F A700 Screen Buffer 1

00 0000 - 3F FFFF 0M - 4MB Total address space

00 0000 - 0F FFFF 0M - 1MB

00 0000 - 07 FFFF 0K - 512k

xx FCFF Screen1 memory end

xx A700 Screen1 Memory start

xx 7C7F Screen2 Memory End

xx 2700 Screen2 Memory Start