From: joef@extro.ucc.su.OZ.AU Subject: AMD Cyrix chips etc. Date: 31 Jul 1992 08:44:47 GMT
I've seen a few posts [and mailed a few back] about problems with the AMD
386 chips and their FPU exception's. Since I saw 3 messages abouth them when
I just had a read through I think I might as well post it to the net for
world-wide flaming by people who own 386/40's.
There is a problem with the AMD's FPU error routine, as compared with the
Intel [and I believe cyrix chips don't have this problem either] - When you
are asking the AMD chip to do a FPU instruction you can get delays of up
to _5_ milliseconds before the chip returns an error so that the Software
FPU emulation can kick in. This [unfortunatly] means that AMD chips go at
about the speed of a 8mhz XT [in real time] when you are asking it to do
anything involving FPU. [Xwindows springs immediatly to mind] so I would
HIGHLY recommend [if you have a AMD chip of course :-)] that you run off
to your local computer shop and pick up a Co-processor. This means you can
then invite your friend over who owns a 486DX/20 and do a huge ray-trace
and laugh at him while he wonders why he bought a slug of a machine :-)