🚀 go-pugleaf

In article <3947@cruzio.santa-cruz.ca.us> aki@cruzio.santa-cruz.ca.us writes:
>
>Doing my thing I hit upon a truly strange op-code:
>
>It's 0F 3D,  i.e. 286+ 2-byte opcode that has 3D as the second
>byte.  Problem is,  that I can't find any reference to it anywhere.
>It looks like it's either something very new or undocumented.

I check inside Microsoft Macro Assembler 5.1 and found nothing.
This includes 80386 instructions.  However, I had to check each
instruction one at the time since there is no summary table
for all opcodes.  Could you indicate (1) references you already check
and (2) context where this instruction appeared.

In old Apple ][, the boot program was executing some text so that
1) you couldn't remove Apple name from EPROM in at least one place or
other modify the EPROM except in a few places
2) you couldn't replace the 6502 chip by a 65C?? (I forget the name, was
a more powerful version of 6502 with more instructions, like the 8088/V20)

I don't think this is possible in Sorftware running in any PC.  In the
6502, empty codes were doing always the same thing and most could
be documented and predicted.  In 80x86 _family_, this is not possible.

>
>I considered the possibility of the 0F being a 8088/8086 POP CS,
>but the surrounding code excludes this.
>
>Anyone have any idea what that opcode does?
>
>Aki.
>-- 
>/  Phone: 408-662 9664   Fax: 662 9676  |  "Aki" pronounced: Ah-Key. I know  \ 
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  \_\    Denis Beauregard  *  internet:beaurega@ireq.hydro.qc.ca
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