Path: utzoo!attcan!uunet!crdgw1!sixhub!davidsen
From: davidsen@sixhub.UUCP (Wm E. Davidsen Jr)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Can you speed up an old 6Mhz IBM-AT to 12Mhz?
Message-ID: <1225@sixhub.UUCP>
Date: 7 Jul 90 02:10:10 GMT
References: <6692@vax1.acs.udel.EDU>
Reply-To: davidsen@sixhub.UUCP (bill davidsen)
Organization: *IX Public Access UNIX, Schenectady NY
Lines: 35

In article <6692@vax1.acs.udel.EDU> bach@vax1.udel.edu (Baskaran Subramaniam) writes:
| 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, the 
| RAM chips have a speed of 120ns.  Would changing the crystal create any problem
| with using these?  Do I have to change the '287 and the RAM chips also?  Do I
| have to change the '286 chip itself?

  You can increase the speed of the *old* AT by putting in a new
crystal. The later ones didn't go any faster, but IBM put a check in the
BIOS to generate an error in POST if you did it. Good marketing... build
slow hardware and put the effort into ways to keep people from speeding
it up!

  The RAM probably will run 8MHz, but I'd replace all of it with at
least 100ns, maybe 80. RAM is just too cheap to take a chance. You will
probably get something which doesn't woirk between 8-10MHz. It's usually
the RAM, and if you go to better RAM you can often go a bit more. The
CPU and FPU will probably run to 10MHz, but I would suggest putting a
heat sink on at least the FPU.

  This is all stuff we did years ago. If it were mine I'd pull the
motherboard and throw it away, and put in a 386SX with 2MB for about
$500. Then it will all work, be within rated speed, and be reliable
enough to be useful.

  The last time I pulled a few AT motherboards I posted them on
misc.forsale as "best offer" and no one wanted them enough to make *any*
offer. The world has moved on.
-- 
bill davidsen - davidsen@sixhub.uucp (uunet!crdgw1!sixhub!davidsen)
    sysop *IX BBS and Public Access UNIX
    moderator of comp.binaries.ibm.pc and 80386 mailing list
"Stupidity, like virtue, is its own reward" -me