revenantOct 13

https://forums.nesdev.org/viewtopic.php?t=26295

wrote up a bit of info on a less common US revision of Micro Machines for the NES, featuring a pretty nasty bug, discovered just a little too late and then worked around by using a PLD to patch a single *bit*. this is what day one patches looked like in 1991!

Show threadcurtmack
@revenant Honestly, that's a pretty professional-looking job. Much cleaner than what Capcom did with the JP 1.0 version of Rock Man X (a.k.a. Mega Man X):
Oct 13 at 11:07pmWeb
Show threadrevenantOct 13

@curtmack bodge wiring is much cheaper than having to design a whole one-off PCB though

(coincidentally the anti-piracy stuff in MMX that prompted that hack is probably one of my favorite such things in a game)

Show threadcurtmackOct 13

@revenant Rock Man X has anti-piracy code that looks for working SRAM; if it finds any, it assumes it's running on a cartridge copier and enables some anti-piracy measures. This routine has an error where it sometimes detects a mirror of the game ROM as "SRAM," randomly informing legitimate purchasers that they have a pirated copy.

The bodge wire disables the ROM chip in those mirror addresses, so the buggy anti-piracy routine behaves properly.

Show threadcurtmackOct 13
@revenant (you clearly know all of this, but I'll leave it for anyone else reading this thread)