Comment by AlyssaRowan
11 years ago
They're slower, but things like this can be really useful if you're golfing for size. They're available on some other chips like the 6502, as well - although how they actually work varies! (And is mostly undocumented, too - anything that wants to use the Z flag after an ADC, for example.)
You can also abuse them as part of things like base change routines sometimes… which is sort of what they're intended for.
The 6502 and variants (65c02, 65816, emulators, etc) have slightly different algorithms for BCD math. Adding illegal BCD numbers and checking the result is one way to identify the processor.