Interrupt 13h Question

[renovatio]

What is the maximum number of sectors I can read with 2h function?

Is there any limitation apart from the AL register (255 max) and the amount of memory?

Thanks...

[bewing]

These sorts of questions are exactly what Ralf Brown's Interrupt List (RBIL) is supposed to help with.
Unfortunately, the answer is BIOS-specific. I haven't looked at my copy of RBIL, but I'd expect that you had best keep your transfers below 64K, and probably <128 sectors (NOT including 128). I have heard that some BIOSes have problems with transfers of 128 sectors, for a different Int13h command -- and I would expect it would happen for all Int13h commands on that BIOS. I always use max 32K transfers, myself.

[renovatio]

I'm sorry if I seemed to be lazy, I didn't know RBIL list of interrupts could help me. Anyway, thanks for your reply.

[abachler]

with sub function 0x02h there is a maximum of 255 sectors per call, use subfunction 0x42h if you want to read more per call, as its limit is 65535 per call

[Love4Boobies]

Not really. The extended services (AH=42H) only allow you to read 127 sectors at a time.