29 Jul
2014
29 Jul
'14
1:21 p.m.
Ken Seefried wrote:
On Jul 29, 2014, at 12:13 PM, Chuck Guzis wrote:
And before that Motorola had the 68030 dump practically all of the
modular programming stuff that had been added to the 68020 in order to
compete with the National 16032 and the Intel iAPX286. I don't remember
if there was a software solution to handle code that used the missing
instructions.
-- Jecel
Which brings up an interesting question--how many
other machines shrunk
their instruction set during the course of evolution, rather than the other
way around?
The MC68060 shed a number of integer mul/div, FP transendentals, and some
variants of conditional MOVE instructions that the MC68040 implemented, as
well as some privileged mode instructions like PTEST. I'm sure there are
others I've forgotten. Motorola provided exception handling software that
would emulate (many) of the unimplemented instructions.