8088 vs. 80c88
trixter at oldskool.org
Thu Feb 12 13:49:17 CST 2009
Jim Leonard wrote:
> So a simple routine to try to identify the 8088 vs. the 80c88
> would look something like:
> mov cx,2 ; test if following instruction will be
> ; repeated twice.
> db 0F3h,26h,0ACh ; rep es: lodsb
> jcxz Yes ; intel non-CMOS chips do not care of rep
> jmp Nope ; before segment prefix override, NEC and
> ; CMOS-tech ones does.
It turns out my information is bad. The bug only asserts itself when an
interrupt occurs during the REP. Buggy CPUs don't continue; later ones
do. So to fix my detection code, I will increase the count in cx to
something much longer, probably f000.
Jim Leonard (trixter at oldskool.org) http://www.oldskool.org/
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