July 2014

Patching the Newton | Dadhacker
“So, how do you fix bugs in a ROM, if you can’t change the image? The basic idea is that you litter the code with indirect jumps that go through a jump table that’s been copied to RAM. When you need to patch something, chances are that you can do tricky and unnatural things to get control at the right spot, fix things up and continue.” This technique hasn’t gone away, of course. Tricky and unnatural = fun.
(tags: programming patch dadhacker rom)