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Speeding up the AT [message #80957] Tue, 04 June 2013 00:01 Go to next message
Anonymous
Karma:
Originally posted by: shonle@csu-cs.UUCP (Greg Shonle)
Message-ID: <2652@csu-cs.UUCP>
Date: Thu, 1-Nov-84 14:06:06 EST
Article-I.D.: csu-cs.2652
Posted: Thu Nov  1 14:06:06 1984
Date-Received: Sun, 11-Nov-84 22:16:38 EST
Distribution: net
Organization: Colo State Univ - CS Dept
Lines: 13

[]

I was just reading in InfoWorld that it is possible to speed up
the PC/AT.  According to the latest InfoWorld, somebody pulled out
the 12 mhz chip, and put an 18 mhz crystal in (the crystal is socketed,
not soldered).  It worked, except for the 80287, a diagnostics program,
and some clock-sensitive software, such as communication programs.
It looks like IBM can speed the AT up by 50% whenever they want to.

-------------------------------------------
 
				    Greg Shonle
	 ...!{boulder,cires,denelcor,hao,hplabs,mit-vax,unmvax}!csu-cs!shonle
Re: Speeding up the AT [message #80960 is a reply to message #80957] Tue, 04 June 2013 00:01 Go to previous messageGo to next message
greenber is currently offline  greenber
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Message-ID: <12400017@acf4.UUCP>
Date: Sun, 11-Nov-84 10:49:00 EST
Article-I.D.: acf4.12400017
Posted: Sun Nov 11 10:49:00 1984
Date-Received: Tue, 13-Nov-84 01:16:11 EST
References: <2652@csu-cs.UUCP>
Organization: New York University
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Nf-ID: #R:csu-cs:-265200:acf4:12400017:000:276
Nf-From: acf4!greenber    Nov 11 10:49:00 1984

<>


Interestingly enough, the only socketed "chip" on the moma-board is the
clock chip.  IBM states (from a usually reliable source) : "We are waiting
for the higher speed FP chip to be fully debugged!"


Ross M. Greenberg  @ NYU   ---->  allegra!cmcl2!acf4!greenber  <----
Re: Speeding up the AT [message #83481 is a reply to message #80957] Mon, 10 June 2013 21:44 Go to previous messageGo to next message
toby is currently offline  toby
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Message-ID: <6331@apple.UUCP>
Date: Tue, 13-Nov-84 12:42:00 EST
Article-I.D.: apple.6331
Posted: Tue Nov 13 12:42:00 1984
Date-Received: Thu, 15-Nov-84 03:05:37 EST
References: <2652@csu-cs.UUCP>
Lines: 19

Sticking a faster clock in one machine is no proof that *all* machines will
Distribution: net
Organization: Apple Education Research Group, Cupertino CA
Lines: 15

work at the faster clock.  Will the machine still work at higher than normal
temperature? Does the machine still pass RFI standards at the higher speed.
Does the machine consume more power now? There was some mention of some 
diagnostics failures, which ones failed? How easy is it going to be to speed
up the 80287? Who gave info world the idea to do this? Who gave them the 
machine? Who loves to spread rumors about future product directions that may
or may not be true?

I'll believe a cheap 80286 system can run at 18MHz when I see it.

toby

(The opinions expressed here are mine and do not reflect those of my   
employer)
Re: Speeding up the AT [message #83490 is a reply to message #80957] Mon, 10 June 2013 21:44 Go to previous messageGo to next message
topher is currently offline  topher
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Message-ID: <455@cyb-eng.UUCP>
Date: Thu, 15-Nov-84 12:46:06 EST
Article-I.D.: cyb-eng.455
Posted: Thu Nov 15 12:46:06 1984
Date-Received: Sat, 17-Nov-84 20:00:43 EST
References: <2652@csu-cs.UUCP>
Distribution: net
Organization: Cyb Systems, Austin, TX
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 >  I was just reading in InfoWorld that it is possible to speed up
 >  the PC/AT.  According to the latest InfoWorld, somebody pulled out
 >  the 12 mhz chip, and put an 18 mhz crystal in (the crystal is socketed,
 >  not soldered).  It worked, except for the 80287, a diagnostics program,
 >  and some clock-sensitive software, such as communication programs.
 >  It looks like IBM can speed the AT up by 50% whenever they want to.

This may be true.  However, before anyone out there either tries to soup up
their own AT, or reaches the conclusion that IBM is playing marketing/demand
games, consider whether or not it will run at 18MHz when:
	the ambient temperature reaches 95F,
	or 40F,
	or the line voltage falls 10%,
	or you get a processor chip that is somehow marginal,
	or you get a memory chip that is just a tad on the slow side,
	or you plug in one more board, loading the bus drivers that much more,
	blah, blah, blah.
Anyone who has every gone through the rigors of preparing a product for
mass production will recognize that broadcasting the conclusion that 'it
can be speeded up 50% any time you want' on the basis of one casual
experiment is a bit premature.
Re: Speeding up the AT [message #83498 is a reply to message #80957] Mon, 10 June 2013 21:44 Go to previous messageGo to next message
kfl is currently offline  kfl
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Message-ID: <386@hoxna.UUCP>
Date: Mon, 12-Nov-84 09:07:49 EST
Article-I.D.: hoxna.386
Posted: Mon Nov 12 09:07:49 1984
Date-Received: Mon, 19-Nov-84 07:40:37 EST
References: <2652@csu-cs.UUCP>
Organization: Bell Labs, Holmdel NJ
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xxx
When changing crystals, I would be especially careful of how the
increased CPU speed affects RAM access and disk access, especially
floppy disks.
Re: Speeding up the AT [message #86435 is a reply to message #80957] Tue, 18 June 2013 23:01 Go to previous messageGo to next message
jec is currently offline  jec
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Message-ID: <1500026@iuvax.UUCP>
Date: Wed, 28-Nov-84 15:31:00 EST
Article-I.D.: iuvax.1500026
Posted: Wed Nov 28 15:31:00 1984
Date-Received: Fri, 30-Nov-84 04:42:51 EST
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Nf-ID: #R:csu-cs:-265200:iuvax:1500026:000:317
Nf-From: iuvax!jec    Nov 28 15:31:00 1984


[]
	I seriously doubt you are really running at 18Mhz.  I suspect that
the clock rate is divided at some point although I don't have the schematics
to back this claim.  If anyone knows for sure you might let us know.

--


					James Conley
					Indiana University
					68K Education Board Project
					..iuvax!jec
Re: Speeding up the AT [message #86468 is a reply to message #80957] Tue, 18 June 2013 23:01 Go to previous messageGo to next message
Anonymous
Karma:
Originally posted by: dan@rna.UUCP (Dan Ts'o)
Message-ID: <330@rna.UUCP>
Date: Sun, 2-Dec-84 00:34:49 EST
Article-I.D.: rna.330
Posted: Sun Dec  2 00:34:49 1984
Date-Received: Tue, 4-Dec-84 08:27:02 EST
References: <2652@csu-cs.UUCP> 
Reply-To: dan@rna.UUCP ( Ts'o)
Organization: Rockefeller Neurobiology, NYC
Lines: 7
Summary: 


	I believe that the PC/AT's clock is divided by three. Thus a
12 Mhz clock is really clocking the CPU and FPU at 4Mhz. 18Mhz -> 6Mhz
which is better than the PC's clock (4.7Mhz ?). But the 80287 at 4Mhz
is worst than the PC's 8087 at 4.7Mhz - essentially same FPU at a
slower clock.
Re: Speeding up the AT [message #86480 is a reply to message #80957] Tue, 18 June 2013 23:01 Go to previous messageGo to next message
b-davis is currently offline  b-davis
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Message-ID: <3132@utah-cs.UUCP>
Date: Mon, 3-Dec-84 11:46:59 EST
Article-I.D.: utah-cs.3132
Posted: Mon Dec  3 11:46:59 1984
Date-Received: Wed, 5-Dec-84 00:46:47 EST
References: <2652@csu-cs.UUCP> <1500026@iuvax.UUCP>
Reply-To: b-davis@utah-cs.UUCP (Brad Davis)
Organization: Univ of Utah CS Dept
Lines: 4
Summary: 

The standard AT uses a 12 mhz clock that is divided by 2 (6 mhz)
for the 80286 and 3 (4 mhz) for the 80287.  If an 18 mhz crystal
were used the clock speeds would be 9 mhz and 6 mhz.  80287's 
can't run at 6 mhz yet (as far as I know).
Re: Speeding up the AT [message #115463 is a reply to message #80957] Wed, 18 September 2013 17:59 Go to previous message
Anonymous
Karma:
Originally posted by: shonle@csu-cs.UUCP (Greg Shonle)
Message-ID: <2683@csu-cs.UUCP>
Date: Thu, 21-Feb-85 02:25:06 EST
Article-I.D.: csu-cs.2683
Posted: Thu Feb 21 02:25:06 1985
Date-Received: Tue, 26-Feb-85 20:12:18 EST
References: <2652@csu-cs.UUCP> <1500026@iuvax.UUCP>
Organization: Colo State Univ - CS Dept (Ft Collins, CO)
Lines: 12

[fnord!]

Just to set the record straight, the 80286 ALWAYS divides the external
clock speed by 2.  Ie, the current 12mhz clock gives a 6mhz effective
speed.  18mhz->9mhz effective.  The 80287 can either use the external
clock line directly, or it can divide by 3.  The AT divides by 3.  This
is controlled by one of the pins.  Therefore, the AT's 287 runs at 4mhz.
Speaking of speeding things up, does anyone know where one can
buy 8-10mhz 286's and 6mhz 287's in small quantities?

				    Greg Shonle
	 ...!{boulder,cires,denelcor,hao,hplabs,mit-vax,unmvax}!csu-cs!shonle
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