How much accuracy can be expected though? Some of what the rom does is background poll hardware. I know I didn't account for any hardware speed in Cloudt other than the CPU.
A for loop doesn't do anything hardware wise but the ISRs are still running and basic ROM and Any TSRs (usually optroms) do their own housekeeping, which may interface with hardware. I guess all background has some I/o instructions. If they always only hit once each and don't result in any looping (or always the same amount of looping) it will be a consistent amount of time for the background. At the very least I would think a fudge factor would be needed to get parity with real world if we are compounding overhead error with big loops . Rex is an interesting variable because it hooks some callbacks for its own housekeeping code (I think to recover from warm resets) so it is expected to change the background overhead. -- John .
