20 Nov
2007
20 Nov
'07
8:44 p.m.
On Nov 20, 2007 11:34 AM, Tony Duell <ard at
p850ug1.demon.co.uk> wrote:
Is it a true 486? or a 486SLC (which is really a Cyrix 386SX with an
internal cache and a couple of the 486 instructions included)? IBM
and TI were second sources for the Cyrix processor. But it really
wasn't instruction compatible with the 486, and most instruction
timings were more 386 like than 486 like. It didn't work like a 486
especially where cache control was involved, even though it had 486 in
the name. But the cache, and better integer multiply circuitry, made
it significantly faster than a 386SX of the same clock speed. That
is, assuming you could run the program to enable the cache, or had
BIOS support for the cache.
Cyrix also made a 486SRX2 which was clock doubled, as well as the
32bit versions, the 486DLC and 486DRX2 which would work in a 386DX
socket.
Anyway, the SLX or SRX2 (which have 386SX pinouts) would be much
easier to adapt to an 80286 socket than a true 486 would be.
Eric
Eric and others:
Ever you had IBM sourced 486 SLC/SLC2/SLC3? Far better than Cyrix/TI
486SLC wannabes. Cyrix/TI utilized 1K cache. IBM had 8K and 16K and
much better optimizations.
Cheers, Wizard
I'd
like to see an 80286 to 80486 upgrade card. It would need to somehow
I have one. It's currently running in the machine I am typing this on.
It's a little module with a TI 486-compatile processor on one side and,
IIRC, the floating poiut coprocessor for it on the other (or at least
that's the only explanation I can find for 2 large PQFPs). A couple of
PLDs and a PLCC 'plug' to go into the 80286 socket.