9 Apr
2018
9 Apr
'18
1:46 p.m.
An interesting and sometimes useful hack at the AI Lab circa 1970 was hooking an oscilloscope to the Program Counter. The high 9 bits drove X (I think) and the low 9 bits drove Y. The display thus showed from where in memory the instructions were being fetched, and brightness represented rate of executing that location. Loops looked like — loops! Unexpected behavior was sometimes clearly evident. Nowadays, even if the PC were easily available, instruction rate is way too fast for a CRT to keep up with, but perhaps a pseudo-random sampling would accomplish the same effect. However, it wasn’t helpful enough to be a great tool, IMHO. — Mike