snugroh@hubcap.clemson.edu (Anto) (06/05/90)
I just bought a used NEC AT-compatible. It has 80286-8MHz. When I opened it, it looked like all memory (ROM and RAM) are for 12 MHz. So I wonder if I can just change the CPU and clock to 12 MHz to get better speed with cheap price. Has anyone ever done that ? There are several x-tals in the mother board (the motherboard has serial and parallel port), but the one that close to CPU is 24 MHz. Anyone know about clock divider by 3 ? If anyone know those stuff, please reply to me. Thanks for any response. -anto- snugroh@hubcap.clemson.edu snugroh@clemson.clemson.edu
silver@xrtll.uucp (Hi Ho Silver) (06/08/90)
In article <9207@hubcap.clemson.edu> snugroh@hubcap.clemson.edu (Anto) writes:
$I just bought a used NEC AT-compatible.
$It has 80286-8MHz.
$When I opened it, it looked like all memory (ROM and RAM) are
$for 12 MHz. So I wonder if I can just change the CPU and clock to 12 MHz to
$get better speed with cheap price.
It probably won't work. There are other items in your system besides
the ROM, RAM and CPU which may be affected. Chances are all the "glue"
chips will be able to run at the higher speed, but keep in mind that the
I/O bus that feeds the expansion slots probably takes its timing directly
from the CPU's clock, so by speeding up the CPU to 12 MHz, you'd also be
speeding up the expansion slots to 12 MHz and chances are at least one
of whatever cards you have plugged in will not work at that rate. There's
another discussion in this group on that topic; you might want to read it.
$There are several x-tals in the mother board (the motherboard has serial and
$parallel port), but the one that close to CPU is 24 MHz.
$Anyone know about clock divider by 3 ?
I'm not familiar with the various chips used to drive 80286s, but I
know on some other microprocessors the crystal frequency was divided by
three. The 24 MHz crystal is probably the correct one.
--
/Nikebo \ Nikebo says "Nikebo knows how to post. Just do it."\silver@xrtll/
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/yunexus!xrtll!silver (L, not 1)\ Hi Ho Silver \ just silver for short /
/Silver: Ever Searching for SNTF \ Life sucks. \ someone buy me a BEER! /hexmoon@bucc2.UUCP (06/09/90)
please post. I too am looking at the possibilities in speeding up a true AT in getting info from a machine feed, some data is lost. Red tape wise, it'd be a lot easier to put in a faster clock then replacing a machine that only flaw is being slow. hexmoon
jca@pnet01.cts.com (John C. Archambeau) (06/10/90)
silver@xrtll.uucp (Hi Ho Silver) writes: >In article <9207@hubcap.clemson.edu> snugroh@hubcap.clemson.edu (Anto) writes: >$I just bought a used NEC AT-compatible. >$It has 80286-8MHz. >$When I opened it, it looked like all memory (ROM and RAM) are >$for 12 MHz. So I wonder if I can just change the CPU and clock to 12 MHz to >$get better speed with cheap price. > > It probably won't work. There are other items in your system besides >the ROM, RAM and CPU which may be affected. Chances are all the "glue" >chips will be able to run at the higher speed, but keep in mind that the >I/O bus that feeds the expansion slots probably takes its timing directly >from the CPU's clock, so by speeding up the CPU to 12 MHz, you'd also be >speeding up the expansion slots to 12 MHz and chances are at least one >of whatever cards you have plugged in will not work at that rate. There's >another discussion in this group on that topic; you might want to read it. > >$There are several x-tals in the mother board (the motherboard has serial and >$parallel port), but the one that close to CPU is 24 MHz. >$Anyone know about clock divider by 3 ? > > I'm not familiar with the various chips used to drive 80286s, but I >know on some other microprocessors the crystal frequency was divided by >three. The 24 MHz crystal is probably the correct one. On a a 286, it's the clock crystal divided by 2 to get the clock speed of the CPU. On the math coprocessor, it's the crystal divided by three or four. // JCA /* **--------------------------------------------------------------------------* ** Flames : /dev/null | Small memory model only for ** ARPANET : crash!pnet01!jca@nosc.mil | Unix? Get the (*bleep*) out ** INTERNET: jca@pnet01.cts.com | of here! ** UUCP : {nosc ucsd hplabs!hd-sdd}!crash!pnet01!jca **--------------------------------------------------------------------------* */