15:03 <proteusguy> For the 8bit computers when memory was just as fast as the CPU a tos register really didn't matter much. But for modern CPUs it's pretty useful.

17:08 <siraben> proteusguy: on the Z80 dereferencing memory is more expensive than working on a register, so I think the gains are worthwhile, e.g. inc hl takes 16 cycles but dereferencing the stack pointer into hl is already 20 cycles

17:37 <lispmacs[work]> 16 cycles to increment a register? Seems like a lot

17:53 <MrMobius> can you do any register to register operations on z80 other than move?

17:56 <siraben> lispmacs[work]: to increment a 16-bit register

17:56 <MrMobius> 4 bit ALU iirc

17:57 <siraben> MrMobius: there's exchanging de and hl IIRC

17:57 <MrMobius> ahh ok so still need memory access for add, or, and, etc

17:57 <siraben> yeah it has a 4 bit ALU because apparently it can go fast enough

17:58 <siraben> http://z80-heaven.wikidot.com/instructions-set:add

17:58 <siraben> here's the valid operands for add

18:09 <MrMobius> oh neat. so you can add register to register