Grr, that's annoying. Here I was trying to come up with a way to do conditional arithemtic in a single register without conditionals, and you point out it's unnecessary. I was close, too - using rotates through the carry and then instructions like SBI $00. I think it's possible, though it needs lots of rotates. (Sequences like: use Dave Dunfield's code up through the second-last instruction (SBI $09), then SBI $F5; RLC; RLC; RLC; RLC; SBI $00; RRC; RRC; RRC; RRC. That gives too wide a gap, but I think it could be modified into the kind of solution I was thinking about.) Still, it was fun to work on. Trying to do things in a ridiculously constrained environment (like conditional arithmetic without conditionals) can be fun. /~\ The ASCII der Mouse \ / Ribbon Campaign X Against HTML mouse at rodents.montreal.qc.ca / \ Email! 7D C8 61 52 5D E7 2D 39 4E F1 31 3E E8 B3 27 4B