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From: coffee@aero.ARPA (Peter C. Coffee)
Newsgroups: comp.sys.intel,comp.sys.ibm.pc
Subject: Re: Clock speed on those darn 80?87 chips ...
Message-ID: <17428@aero.ARPA>
Date: Fri, 18-Sep-87 19:34:45 EDT
Article-I.D.: aero.17428
Posted: Fri Sep 18 19:34:45 1987
Date-Received: Sun, 20-Sep-87 11:35:44 EDT
References: <454@hubcap.UUCP> <17263@aero.ARPA> <7385@steinmetz.steinmetz.UUCP>
Reply-To: coffee@aero.UUCP (Peter C. Coffee)
Distribution: na
Organization: The Aerospace Corporation, El Segundo, CA
Lines: 18
Keywords: 8087, 80287, et al those math processors ....
Xref: mnetor comp.sys.intel:350 comp.sys.ibm.pc:7981

In article <7385@steinmetz.steinmetz.UUCP>...bill davidsen writes:
>In article <17263@aero.ARPA> coffee@aero.UUCP (Peter C. Coffee) writes:
>
>|8088, 8086, and 8087 run at board clock rate.
>|80286 runs at 1/2 board clock rate. I don't know about the 80386.
>|80287 runs at 1/3 board clock rate. I don't know about the 80387.
>
>This isn't correct. The speed of the chip is not provided by the clock
>fed to it...For example, there is a company which plugs an 80287 running
>at 10MHz into the socket of an existing 80287.

You're kidding, right? You never noticed the CRYSTAL(!!!!) on the little
daughterboard that holds said 80287??? I specifically said, you can feed
the numeric chip its own clock if you want to; and yes, the 8087's execution
unit can also run asynchronously with its control unit.

Geez Louise--plug the chip in to 5VDC and off it goes at 10MHz...wait til
the crystal manufacturers find out about this...mutter, mutter.