Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!purdue!tut.cis.ohio-state.edu!ucbvax!LONEX.RADC.AF.MIL!koziarzw
From: koziarzw@LONEX.RADC.AF.MIL (Walter Koziarz)
Newsgroups: comp.sys.zenith.z100
Subject: 10MHz 8087 & 8088
Message-ID: <8907191451.AA17733@lonex1.radc.af.mil>
Date: 19 Jul 89 14:50:58 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 36

I wrote:

>>The 10MHz clock-rate tinker seems (from my fractal-image oriented perspective)
>>to be much more worth pursuing.  The only real question I am still uncertain
>>of with regard to 10MHz is whether the PALs on the 8087 board can keep-up.

Ken  (absolutely correctly) responds:

>Another serious consideration here is the 8087 itself, which is
>particularly prone to heat (hence speed) related problems.  When I
>increased the speed on my 100 from 5 to 8 Mhz, I found that the
>machine would lock up at odd times, unpredictably.  I put in an 8088-2
>(8 Mhz model) and that improved the situation slightly, then I put in
>an 8087-2 (when the prices were ~$100) and voila - no more lockups,
>ever.  The PALs, while probably not rated for 8 Mhz operation, had no
>problem whatsoever.  My H-100 continues to run at 8 Mhz with 100%
>reliability (knock on wood...).

>Ken

>Kenneth R. van Wyk
>Technical Coordinator, Computer Emergency Response Team
>Software Engineering Institute
>Carnegie Mellon University
>Internet: <krvw@SEI.CMU.EDU>

I had ommitted the statements that an integral part of the 10MHz work is
acquiring an 8088-1 and an 8087-1.  These are both rated for 10MHz operation.
Gern also suggests replacing the clock generator (8284) with a newer 10MHz
rated part (8284-1, I think).  Appologies for any confusion!!!

BTW, Ken, are you using the ORIGINAL PALs from the 5MHz 8087 board?

Cheers,

Walt K.