[net.micro.pc] AT speedup

maddox@renoir.berkeley.edu (William Maddox) (05/11/86)

Keywords:

I have recently seen an AT clone running at 10mhz, and was quite
impressed at the noticeable improvement in responsiveness under Xenix.
Has anyone *reliably* increased the speed of a genuine IBM AT to
10Mhz?  I am not interested in simply putting in a faster crystal and
hoping that it will work, that the 286 will not overheat, etc.  At a
minimum, I would assume that a certified 10mhz 80286 would be needed.
Also, how fast need the memory be?  I have no idea where to get faster
piggyback chips should they not be fast enough.

I would greatly appreciate hearing from anyone who has succesfully
upgraded an AT to 10Mhz, as well as any reports on reliability
problems.  Sources and prices for the required components would also
be helpful.  I will post a summary to the net.  Thanks.

Bill Maddox
UUCP:  ucbvax!renoir!maddox
ARPA:  maddox@renoir.berkeley.edu

2212msr@whuts.UUCP (ROBIN) (05/13/86)

> Keywords:
> 
> I have recently seen an AT clone running at 10mhz, and was quite
> impressed at the noticeable improvement in responsiveness under Xenix.
> Has anyone *reliably* increased the speed of a genuine IBM AT to
> 10Mhz?  I am not interested in simply putting in a faster crystal and
> hoping that it will work, that the 286 will not overheat, etc.  At a
> minimum, I would assume that a certified 10mhz 80286 would be needed.
> Also, how fast need the memory be?  I have no idea where to get faster
> piggyback chips should they not be fast enough.
> 
> I would greatly appreciate hearing from anyone who has succesfully
> upgraded an AT to 10Mhz, as well as any reports on reliability
> problems.  Sources and prices for the required components would also
> be helpful.  I will post a summary to the net.  Thanks.
> 
> Bill Maddox
> UUCP:  ucbvax!renoir!maddox
> ARPA:  maddox@renoir.berkeley.edu

I've got a 'true' AT, purchased in September 1984, which I run at 10Mhz as
a normal event.  I've been doing this using a Megahertz Corp. Turboswitch II.
This provides a switch for 6Mhz/'Turbo' operation and a rotary
switch to select speeds in .5Mhz increments to either 11 or 12Mhz (I'm
not on my machine so I can't check.)  Discussion w/Dave Stafford at Mhz
indicates that 60 -70% of the stock machines tried have been able to run
successfully.  System configuration includes 80287 and 3M of RAM on
AST Advantage! board.  Only caveat seems to be that 80287 run noticeably
warmer than before.  This might be expected, considering that theis
chip is only rated at 5mhz and is running at 6.66Mhz.  For what it's
worth, Norton's Utilities Sysinfo yields a value of 8.4 average.
(Obviously I have no way of measuring actual clock speed and am taking
Mhz's word for it.)  Mhz products seem quite reliable and I've been
very pleased w/technical help. (Mhz is in Salt Lake City - see PC or
Byte for address/phone no.)

Max S. Robin 
AT&T Bell Laboratories
email:whuxg!2212msr
voice:201-386-6865