Mastering CHIP-8

While trying to nail down the last few bugs in my own chip-8 emulator I consulted other emulators on github (there are tons). Weirdly, some instructions behave slightly differently with every emulator. I found this guide to be the most complete one and hence thought it's worth bringing up. However, I could not find consensus on what "borrow" means for the SUB instructions (8XY5 and 8XY7) - most implementations set the borrow bit even when the two operands are equal.

In the early 90s CHIP-8 was moderately popular on HP-48 calculators, most interpreter/emulators had no problem running at "full speed". I don't remember if they were assembly or RPL/RPN or what.

Superficially based on long distant memories CHIP-8 games somewhat resembled Atari 2600 games in resolution and gameplay. So they were a lot of fun for folks who measured fun via gameplay, but not so fun for folks who measured fun via pixel resolution or feature checklists, for example.

The Atari 2600 comparison gives you some idea of the game genres available, some pacman and pong and driving games not so much FPS or platformers or fighting games. I am pretty sure there was a good space invaders.

I have often thought it would make a decent assembly language training environment. People do like games and something like pong in CHIP-8 is a reasonable goal.