Quote:
Originally Posted by Galahad/FLT
Its just not advised to use TAS at all on Amiga... EVER!
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Have you checked whether that applies when the operand is a data register? I'm pretty sure it doesn't, though maybe someone with access to a logic analyser could check for sure.
When the TAS operand refers to memory is where there are problems. It probably can't be used in chip RAM (or slow $C00000 RAM). Some true fast RAM expansions might not support read-modify-write cycles either.
Apparently Commodore's Janus PC Bridgeboard software uses TAS with memory operand. But in that case, presumably the memory is on the bridgeboard, so the software knows the the R-M-W cycle is supported.