[comp.sys.ibm.pc.hardware] AMD's 80C287

a72@mindlink.UUCP (Raman Anand) (07/04/90)

I have a baby 286 12Mhz motherboard. I would like to know if its okay to
install an AMD 80C287 math co-processor in it. Has anybody done this?
Raman

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* Ramanjeet Singh Anand                                            *
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kislik@boole.seas.ucla.edu (Maxim Kislik/;093090) (07/06/90)

I remember that some 386s can handle a 287 as a co-processor.
How can I tell whether I can or cannot do this?

Max.

phil@brahms.amd.com (Phil Ngai) (07/06/90)

In article <2347@mindlink.UUCP> a72@mindlink.UUCP (Raman Anand) writes:
|
|I have a baby 286 12Mhz motherboard. I would like to know if its okay to
|install an AMD 80C287 math co-processor in it. Has anybody done this?

Speaking of the Am80C287, there seems to be some misunderstanding
about the extent of the product offering.  The product is being
advertised in the US. I don't think AMD is ready to go international
with this yet. Readers outside the US should probably wait until
they see advertisments with availability information.

Discussions on USENET do not constitute an advertisment or an
official offer of availability.

Mr. Anand, you seem to be in Canada so I don't know exactly where
that leaves you. Why don't you try the 800 number and see if the
call goes through.

I believe the 287 gets a clock 2/3 of the 286, so a 10 Mhz 287
should work just fine.

Of course, I do not speak for the company.

--
--
Phil Ngai, phil@amd.com		{uunet,decwrl,ucbvax}!amdcad!phil
PALASM 90: it's not the same old PALASM any more!

grege@gold.GVG.TEK.COM (Greg Ebert) (07/06/90)

In article <837@lee.SEAS.UCLA.EDU> kislik@boole.seas.ucla.edu (Maxim Kislik/;093090) writes:
>I remember that some 386s can handle a 287 as a co-processor.
>How can I tell whether I can or cannot do this?
>

According to my Intel databook, an 80287 is a 40-pin DIP device, and the
80387 is a pin grid array (PGA) device. So, I'd just look at the sockets.
An 80387 has 2 'rows' of pins which form a square; don't confuse it with a
socket for a Weitek, which is larger.

When I was at AST Research, I seem to recall our first '386 system had a
socket for an 80287.

The 80386 has an internal mode bit which tells it to run 16-bit (80287)
cycles or 32-bit (80387) coprocessor access cycles. Your setup utility MUST
have some sort of selection for this.