Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!samsung!rex!uflorida!novavax!rm1!browner
From: browner@rm1.UUCP (Michael Browner)
Newsgroups: comp.sys.ibm.pc
Subject: Re: 8087 Coprocessor
Message-ID: <890@rm1.UUCP>
Date: 20 Jul 90 14:20:29 GMT
References: <1990Jul11.172043.525@bigsur.uucp> <673@mtune.ATT.COM>
Organization: Racal Milgo, Sunrise, FL
Lines: 13

In <673@mtune.ATT.COM> klh@mtune.ATT.COM (Ken Hinds) writes:

>Well, I have a dual speed 8088 micro processor in my Leading Edge 
>Model D and I have added an 8087 math coprocessore but, it is listed
>as an 8087-2  which implies dual speed... Sorry I don't recall the
>manufacturer but, I'm sure you could find it if you ask for it specifically.

The 8087-2 does not imply dual speed the -2 designation means the chip will
run the 8Mhz.  The 8087-1 will run 10Mhz, while the 8087-3 is a 5Mhz chip.
As for the orignal post, I tried running a 8087-3 in a turbo XT, if the 
machine was booted at 4.77Mhz it would run, if I changed the speed to 8Mhz
after it booted or booted at 8Mhz then it would lock up.  My advice is get
a 8087 that matches the highest speed of the machine.