1/n Twitter-friend posted description of a real brain-twister of a bug, which reminds me of my personal favorite-ever-hardest-bug-to-find, so.. here is that tale... cast your mind back to 1988 - so long ago I suspect most of you were just a glint in your dad's eye.. ;-).. back in the days of 8-bit micros, in this case the Amstrad CPC (a popular - in Europe - Z80-based home computer). I worked for a games company, I was doing a conversion [i.e. rewrite] of Sega's "Shinobi" arcade machine onto this machine..

Anecdote: For 15 years floppy disk copy protection was fun cat+mouse hackery (Apple2, C64, Amiga; I was friends with the XCopy guys+I did 'Cyclone' hw copier) with lots of clever/complex tricks (sector sync, errors, long tracks, fat tracks, short tracks, 'weak bits' etc etc)... and there were all these nuances to how you'd try to detect and copy them if you were a pirate, or how to prevent copying (and yet still be able to commercially duplicate disks), and I dabbled on both sides for fun and profit..