8088 vs. 80c88

Jim Leonard 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/
Help our electronic games project:           http://www.mobygames.com/
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