20 Oct
2010
20 Oct
'10
10:18 a.m.
Once, after doing something stupid (I'm not sayin'), I had a killed Alto on
my hands. To find the bug, I put a Biomation logic analyzer on the
backplane microcode address bits. Using a listing of the microcode I was
able to figure out which task was running when and that pointed out the loop
in the microcode. I was then able to work backward from the task logic to
figure the bug.
This is made possible because the Alto backplane was wirewrapped, which
meant that the signals are available for easy probing (and logic analyzer
pins).
Once upon a time I used to say "What I wouldn't give to have an Alto
again". Now, I know it's not $30,100.