6 Nov
1998
6 Nov
'98
4:34 p.m.
Speaking of which, I read in a PC repair book that the 486SX is a
486DX with certain lines cut to disable the math coprocessor. The
thing that went into the coprocessor socket was a rebranded 486DX
that took over all functions of the SX when installed. Anyone know
about this?
that's
the
bus
Philip.Belben(a)pgen.com wrote:
>> No thanks to whoever said the 8088 and 8086 were the same thing. If
> the case,
the Pentium and the 80386 are the same thing :-)
>In general terms, without getting into a lot of super-geek discussion, 8086
>and 8088 are in the same category in that they are both predominantly
an XT
class
processor, despite the 8 and 16 bit differences....
Yes, to say that the 8088 and 8086 were the same is incorrect, but they
_basically_ had the same core and everything... it was just the data was 8 bit on the 8088 and 16-bit on the 8086. They were
fully
compatible
program-wise, just that the 8086 was faster as it could
push 2x data
over
the 8088.
Comparing the 80386 and the Pentium wouldn't be fair, tho. Comparing
the
80386SX (with the 16-bit data bus) and the 80386DX
(with the 32-bit
data
bus) would be a lot better comparison... as again, the
chips were fully
compatible, but the DX's were faster due to the larger data bus.
Just the way I seem to remember it...
Roger "Merch" Merchberger
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6 Nov
6 Nov
4:23 p.m.
New subject: 486DX/SX (was: Re: Classic != IBM AT)
Speaking of which, I read in a PC repair book that the
486SX is a
486DX with certain lines cut to disable the math coprocessor. The
thing that went into the coprocessor socket was a rebranded 486DX
that took over all functions of the SX when installed. Anyone know
about this?
PC Magazine back in the early 90's had something that mentioned this. If I
remember correctly it was one of the Dvorak columns. He mentioned that the
486SX was basically a marketing ploy by Intel to allow them to get rid of
486DX chips with defective Math CoPro units.
As for a Math CoPro for the 486, I'm not sure I ever saw a 487 chip, but I
always figured that they took the chips that didn't cut it as a normal
processor but had a good Math CoPro, and sold them as 487's.
I've no idea if this is true, but it made sense to me, since why through
out a chip with a good processor, with you can just package it as a 486SX,
and sell it at reduced cost. Sounds to me like everyone won. After all,
how many people really felt the need for a Math CoProcessor in the early
90's? I added one to a 386sx laptop in January of '94 when I was forced to
go from my 486DX/33 to a 386SX/16 laptop since I was mainly using it for
Linux, and didn't want to have to emulate the math functions, still I don't
know that I needed it.
Zane
| Zane H. Healy | UNIX Systems Adminstrator |
| healyzh(a)ix.netcom.com (primary) | Linux Enthusiast |
| healyzh(a)holonet.net (alternate) | Classic Computer Collector |
+----------------------------------+----------------------------+
| Empire of the Petal Throne and Traveller Role Playing, |
| and Zane's Computer Museum. |
| http://www.dragonfire.net/~healyzh/ |
6:10 p.m.
New subject: 486DX/SX (was: Re: Classic != IBM AT)
On Fri, 6 Nov 1998, Zane H. Healy wrote:
As for a Math CoPro for the 486, I'm not sure I
ever saw a 487 chip, but I
always figured that they took the chips that didn't cut it as a normal
processor but had a good Math CoPro, and sold them as 487's.
Has it been 10 years since the 486 came out? It must be getting close.
In any case, I think Max was right about the 487 really being just a 486
in a different package, and the 486SX was disabled by some logic when the
487 was present. I seem to recall that some software/hardware was able to
use the 486SX/487 combo as a crude multiprocessor box.
-- Doug
2:13 p.m.
New subject: 486DX/SX (was: Re: Classic != IBM AT)
Date: Fri, 6 Nov 1998 23:10:07 -0600 (CST)
Reply-to: classiccmp(a)u.washington.edu
From: Doug Yowza <yowza(a)yowza.com>
To: "Discussion re-collecting of classic computers"
<classiccmp(a)u.washington.edu>
Subject: Re: 486DX/SX (was: Re: Classic != IBM AT)
X-To: Discussion re-collecting of classic computers
<classiccmp(a)u.washington.edu>
On Fri, 6 Nov 1998, Zane H. Healy wrote:
Correct to restate:
487 is like 486dx with extra 1 pin and wired in a way to turn off the
486sx. Wasteful and expensive.
I usually don't personally OWN any SX machines unless for a very
good reason in very specific types like notebooks. No point in
saving few bucks.
original Celerons are like today's Pentium PRO SX but the 300A and
333 is fine Celerons.
Jason D.
As for a Math CoPro for the 486, I'm not sure
I ever saw a 487 chip, but I
always figured that they took the chips that didn't cut it as a normal
processor but had a good Math CoPro, and sold them as 487's.
Has it been 10 years since the 486 came out? It must be getting close.
In any case, I think Max was right about the 487 really being just a 486
in a different package, and the 486SX was disabled by some logic when the
487 was present. I seem to recall that some software/hardware was able to
use the 486SX/487 combo as a crude multiprocessor box.
-- Doug
email: jpero(a)cgocable.net
Pero, Jason D.
7:04 p.m.
New subject: 487 and Marketing Breakthroughs (was Re: 486DX/SX (was: Re: Classic != IBM AT))
"Zane H. Healy" <healyzh(a)ix.netcom.com> wrote:
As for a Math CoPro for the 486, I'm not sure I
ever saw a 487 chip, but I
always figured that they took the chips that didn't cut it as a normal
processor but had a good Math CoPro, and sold them as 487's.
No. The 487 is a *fully* functional 486DX, and it has to be, because when
you plug it into a 487 socket it disables your 486SX completely and takes
over.
The 487 is NOT a "math coprocessor". It's a "Marketing
Breakthrough" (*),
or so they had hoped.
The made the pinouts of the 486 and 487 slightly different, so that you
couldn't take out your old 486SX and simply install the 487 in its place,
which would leave you with a spare 486SX to give to a friend, i.e., less
sales of new chips for Intel.
Part of the reason it didn't work out in practice is that 486DX chips
were generally available for less money than the expensive retail-box
487.
Cheers,
Eric
(*) If you're not familiar with the concept of a Marketing Breakthrough,
see this advertisement which appeared in newspapers nationally a few
years ago:
http://www.milk.com/wall-o-shame/dish.html
Note that every statement in the advertisement is literally true; they
even utilize italics to emphasize the fact that the product is nothing
special.
I didn't buy their antenna, but I offered to pay them up to $20 for a
large poster of the advertisement. Unfortunately they never replied.
9391
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9391
days old
4 comments
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participants (5)
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eric＠brouhaha.com -
healyzh＠ix.netcom.com -
jpero＠pop.cgocable.net -
maxeskin＠hotmail.com -
yowza＠yowza.com