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From: roy@gitpyr.UUCP (Roy J. Mongiovi)
Newsgroups: net.micro.pc
Subject: Re: Detection of the Math Co-processor
Message-ID: <227@gitpyr.UUCP>
Date: Thu, 20-Sep-84 13:11:19 EDT
Article-I.D.: gitpyr.227
Posted: Thu Sep 20 13:11:19 1984
Date-Received: Wed, 26-Sep-84 07:29:01 EDT
References: <206@gitpyr.UUCP> <404@intelca.UUCP>
Organization: Georgia Institute of Technology, Atlanta, GA
Lines: 25

> Well, how about running a co-processor instruction and seeing if anything
> happens?  If on an 8088 a coprocessor instruction is executed and there
> isn't anything there listening to do anything with it, *nothing* happens
> (suprise?)  Although this will require a little assembly language
> (horrors) it is pretty foolproof.....
> 
> Ken Shoemaker, Intel, Santa Clara, Ca.
> {pur-ee,hplabs,amd,scgvaxd,dual,idi,omsvax}!intelca!kds

When you issue a command to the 8087, you have no way to know when the
result is complete except for issuing a WAIT instruction on the 8088.
This instruction halts the machine until the 8087 interrupts it.  If
there is no 8087, there will be no interrupt.  But here is your poor
little 8088 sitting there (forever) waiting for that interrupt.  How
does that help detect the presence of an 8087?  Is there some particular
8087 instruction that takes a predictable amount of time to execute
(so that a delay loop could be built to wait for the instruction to
complete) AND which produces predictable results both when the 8087 is
absent and present?
-- 
Roy J. Mongiovi.  Office of Computing Services.
Georgia Institute of Technology, Atlanta GA  30332
Phone:	(404) 894-6163,	(404) 894-4660 [messages]
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