29 Jul
2014
29 Jul
'14
9:54 a.m.
On Jul 29, 2014, at 12:13 PM, Chuck Guzis <cclist at sydex.com> wrote:
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 PowerPC 601 retained a number of instructions inherited
from POWER that were dropped in subsequent
second-generation
CPUs (603/604). It wasn't a straightforward shrink, though,
as some additional instructions were added (FRES, for example,
the fast floating-point reciprocal estimate, is 603 and up and
is optional).
A lot of the POWER instructions jettisoned were ones one might
traditionally associate with "business logic" like one might
see on an IBM mainframe; instructions like lscbx, which is a
weird-ass instruction but could certainly have applications
in a specific domain.
- Dave