[comp.sys.ibm.pc.hardware] Various 486 questions

rose@malibu.sedd.trw.com (02/21/91)

I have three questions:

1) I have seen a lot of recent price drops in 486/25 machines.
For example in the last 6 months Gateway 2000 has dropped
there 486/25 with 4 MB and 150 MB HD from $5295 to $3995
and increased the ram to 8MB and HD to 200 MB. Also there are
several unknowns for as low as $3100 for a 486/25 w/ 4MB and
200 MB HD, super VGA, 1MB on board, etc.  Is there any specific
reason that prices have dropped so drastically recently? And 
any opinion on whether these prices will continue down or start
back up?

2)  This has probably been asked before but I missed it so here 
goes.
   Does the 486 machine truly contain a built in math co-processor?
Will "any" software that requires or can use a co-processor
be able to run on the 486?  If the above is true: then why does 
Tri-Star advertise a "CAD" system which contains an 80387?
This was in the computer shopper.  The system contains a digitizer
in addition to the basic computer.

3) Is there any specific software and methods for testing the 
true compatability and speed of a 486 machine?

Thanks for any info in advance.

Marc

ganter@urz.unibas.ch (02/21/91)

In article <708.27c232c6@malibu.sedd.trw.com>, rose@malibu.sedd.trw.com writes:

> 1) I have seen a lot of recent price drops in 486/25 machines.
..stuff deleted...
> Is there any specific
> reason that prices have dropped so drastically recently? And 
> any opinion on whether these prices will continue down or start
> back up?

I think, there are still some 486/25 with B9 mask around. These are
told to have bugs, that prohibit multiprocessor use without external
logic (delivered by Intel with the processor). The main problem wouldn't
be the actual processor, but an eventual newer one (connect pin x with 
ground ..., etc). I don't think, that a C1 or higher would run in such
an environement. Because of these bugs, the machines containing them are
sometimes much cheaper. If You are kind with Your B9-486 all that stuff
perhaps doesn't matter for You. But I'd be carefull.
Another reason is certainly the 486/33 entering the market now.
 
>    Does the 486 machine truly contain a built in math co-processor?
> Will "any" software that requires or can use a co-processor
> be able to run on the 486?  If the above is true: then why does 
> Tri-Star advertise a "CAD" system which contains an 80387?
> This was in the computer shopper.  The system contains a digitizer
> in addition to the basic computer.

Yes, the 486 contains a full 387 coprocessor. The 486 built in FPU is faster 
(i.e. fever clock counts for some instructions) and has the same parallel
facilites as the 386/387 processors have. 
Perhaps the 387 is meant as the built in 387 (Or do they use a second one
only for the digitizer part ?).

Most 486 boards have a second socket for the Weitek 4167 FPU (not compatible
to the 387, but faster).
 
Robert

Robert Ganter
University of Basel
Switzerland
ganter@urz.unibas.ch

wk0x+@andrew.cmu.edu (William Stephen Kish) (02/22/91)

   Yes, the i486 does have a numeric coprocessor built in.  It is
basically a '387, but FP performance is somewhat enhanced since it is on
the same chip as the rest of the processor.

Bill Kish
Carnegie Mellon University
wk0x+@andrew.cmu.edu 

gw1e+@andrew.cmu.edu (Gabriel M. Wachob) (02/22/91)

It is true that the 387 is built into the 486. I just bought one of
those oh-so-cheap 486/25's. I think the reason they are getting cheaper
is becuase the 486/33's are starting to come out and because (maybe) the
486/50's (yeah, that's right, 50Mhz!!) will start being produced or
shipped or somthing soon...
I have no idea whether the price will drop or go up.. But, from past
experience, it shouldn't go up much if at all.
-gmw

davidh@garfield.cs.mun.ca (David Hansen) (03/12/91)

I just obtained a good grant.  Should I
buy a 486??  I use huge spreadsheets
and I need the speed.  I need
complete compatibility with all DOS
applications, however.  Any advice?