16 Jun
2016
16 Jun
'16
12:54 p.m.
On Thu, Jun 16, 2016 at 12:53:15PM -0400, Peter Hiscocks via talk wrote:
The Commodore PET and 64 had a 60Hz real-time-interrupt that did a bunch of housekeeping. You could patch your own routines into it, which was really handy.
Wow so the original C64 actually passed 9V AC on a pair of power supply pins for the clock, while later models had an onboard crystal. I didn't know that. That would make doing a replacement power supply a bit tricky.
After a particularly nasty bug, that's where I learned about the importance of semaphores in controlling access to shared resources ;)
Good lesseon to learn early. -- Len Sorensen