Changing self-timer delay
I'm just wondering how easy it would be to change the self-timer delay in the red PV2s. Would it simply be a matter of hex editing a value other than 20 seconds in the firmware, or is it more complex than that? If it's the former, does anyone know where in the 6550 firmware the selftimer delay value is stored?

It's easy enough to boost to 15 seconds, but no higher. For some reason, they used the lower four bits of the variable as the timer, and the higher four bits as some kind of flag. It would be a royal pain to split this out into 2 proper variables.

Where exactly is it in the 6550 red firmware? I may be able to make a longer timer. How long do people want the timer?

Don't know where it's in the 6550 firmware. I documented it in the 6410 firmware analysis available from morcheeba's site. You can probably find it in the 6550 firmware binary by searching for "e0 1a c8". R0 is loaded with 1a, and then it gets stored in the variable. The 1x part of the number is a flag, and the xa part is the timer.

Most of the routines are the same between the 6410 and 6550 - though obviously located at different locations in memory. If you have my partially commented full disassembly of the 6550 FW, then you could probably find it fairly quick.