Path: utzoo!utgpu!news-server.csri.toronto.edu!mailrus!wuarchive!cs.utexas.edu!rice!uupsi!rodan!amichiel
From: amichiel@rodan.acs.syr.edu (Allen J Michielsen)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Can you speed up an old 6Mhz IBM-AT to 12Mhz?
Message-ID: <3816@rodan.acs.syr.edu>
Date: 6 Jul 90 04:05:42 GMT
References: <6692@vax1.acs.udel.EDU> <57993@bbn.BBN.COM>
Reply-To: amichiel@rodan.acs.syr.edu (Allen J Michielsen)
Organization: Syracuse University, Syracuse, NY
Lines: 24

In article <57993@bbn.BBN.COM> sher@labs-n.bbn.com (Lawrence D. Sher) writes:
>In article <6692@vax1.acs.udel.EDU> bach@vax1.udel.edu (Baskaran Subramaniam) 
>>Is it possible to speed up an old 6Mhz IBM-AT (not a compatible) to 12Mhz
>>by changing the crystal in it?
>>We have an 80287/6Mhz and 512K RAM+1128K AST Rampage card in it. I think, th
>>RAM chips have a speed of 120ns.  Would changing the crystal create any probl
>>with using these?  Do I have to change the '287 and the RAM chips also?  Do I
>>have to change the '286 chip itself?
>Putting in a higher speed crystal will work, with increasing flakiness the
>higher the speed.
>The Isa bus has
>practical upper limit of just about 8 MHz.  Even at 8.5 MHz, you may already
>find some intermittent trouble, like in the disk controller.  I wouldn't try
>for more than 8.0 MHz.
  If the at bus has a practical upper limit of just about 8 Mhz, then all the
clone 10 & 12 Mhz bus computers must not work.  PC magazine had a article on
doing this.  Of course, the 286 & 287 will have to be scrapped.  I too
would be weary of taking a old war-horse 6 mhz at above 8 Mhz.  But hey
buy a 12 Mhz 286 (If you can find 1 with the right config--try harris)
and try it.  After getting a good max speed you'll be happy wiith, get
a 287 to match it.  When you get all done, if you pay yourslef $ 2 an hour
ypou just spend more than it costs to get a new 12 mhz motherboard.  But 
boy what a sense of self accomplishment you'll have.
al