Microport UNIX System V/386 v 2.1 (ca 1987) uses mod R/M bytes for
the control register mov instructions where the mod bits are 0,
even though the 80386 spec claims they are always 1's. The fact
that it ran at all clearly indicates the real chips (at least 386
and 486) just ignores the bits and
On Fri, 27 Jul 2012, Matthew Ogilvie wrote:
Microport UNIX System V/386 v 2.1 (ca 1987) uses mod R/M bytes for
the control register mov instructions where the mod bits are 0,
even though the 80386 spec claims they are always 1's. The fact
that it ran at all clearly indicates the real chips
