Path: utzoo!utgpu!news-server.csri.toronto.edu!mailrus!ames!uhccux!robin
From: robin@uhccux.uhcc.Hawaii.Edu (Robin Amano)
Newsgroups: comp.sys.ibm.pc.hardware
Subject: Re: IBM AT model 068 Speedup
Keywords: 6Mhz machine
Message-ID: <8861@uhccux.uhcc.Hawaii.Edu>
Date: 4 Aug 90 00:43:12 GMT
References: <1904@hsi86.hsi.UUCP>
Reply-To: robin@uhccux.UUCP (Robin Amano)
Distribution: usa
Organization: University of Hawaii
Lines: 14

In article <1904@hsi86.hsi.UUCP> tankus@hsi.UUCP (Ed Tankus) writes:
>I have the above machine and would like to rev this sucker up to
>8mhz (minimally) or 10Mhz (preferably).  I recall these machines
>may have had something in the POST to detect clock speed but this
>could be defeated once the POST was done.  Is this correct??
>

You are correct.  I can't remember exactly what version, but the older AT
machines need the rom replaced, when you change the crystal.  Find a newer
version take out the rom copy it into an eprom(27256-15) replace your old
rom and crystal and you should be set.  I think it costs an arm and a leg
to get the rom from IBM, although it's probably not exactly legal to copy 
the rom, I think.  Anyway I'll dig up the info and let you know what 
version we used.