🚀 go-pugleaf

aki@cruzio.santa-cruz.ca.us writes:

>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.

According to the Intel 80286 Spec, there are several candidates, none of
which quite matches what you've got, but here's what I've found:

0f 06 CLTS - Clear Task Switched Flag (protected mode)

0f 02 LAR - Load Access Rights Byte (protected mode)

0f 01 LGDT/LIDT Load Global/Interrupt Descriptor Table Register
       Also used for Load Machine Status Word (Protected mode)
       Also used for SGDT/SIDT Store Global/Interrupt Descriptor etc.

0f 00 LLDT - Load Local Descriptor Table Register (protected mode)
             Also Load Task Register (protected mode)

0f 03 LSL - Load Segment Limit (protected mode)


So most likely what you've got is a 386 or 486 operand or an undocumented
feature.  My question is: does this actually execute or do you get a trap?

It's most likely that this is a direct microprocessor control code.  From
what application does it come?  386MAX? MS-Windows? QEMM? Desqview? or any
other app capable of manipulating the cpu directly?

Let me know,

BobK