[comp.sys.ibm.pc.misc] Speeding up an Old '286

crm@icad.com (Christopher McConnell) (11/06/90)

I have an old AT-286 clone which runs at 8mhz, using a 16mhz clock
crystal.  I understand that I can speed up the CPU by changing to a
faster crystal.  I tried using a 18mhz crystal and I was able to
only access 2 megs of my memory.  I tried using a 20mhz crystal and
I only could access the 1 meg of memory on the motherboard.  My
system is:
	1 meg of 150ns memory on motherboard
	2 megs of 120ns memory on a JRAM-AT card as extended
			memory.
Question:
	Is there something else I have to do to speed up the CPU?
and
	What are other inexpensive ways to get more speed without
	a lot of cost?  I am already using SmartDrive which came
	with windows.

I basically use the computer for Windows/3, C++, games, etc.
Please respond via email and I will post a summary.  Thanks,

						- Chris
						  crm@icad.com

crm@icad.com (Christopher McConnell) (11/13/90)

I asked this question before, and I received only one reply, which was
to go all the way and install a new 386 motherboard.  What I really want
to know is, how does one 'push' their CPU to a faster speed?  Is it just
changing the crystal, or is there anything more to it?

							- Chris
							  crm@icad.com

PS:  My reply was so far:

From: kaleb@thyme.Jpl.Nasa.Gov (Kaleb Keithley	)

Well, if you're adept at changing crystals, then you should be able
to handle a mother board swap.  For about $350 you can swap you 286
mother board for a 20mhz 386SX board.  Then you'll have to add memory,
because most of the 386SX boards use SIMM or SIPP memory, currently
running about $50 per MEG.  My 16mhz 386SX scored 18 on Norton's 4.5 SI.
compared to the 7 or 8 you would get with your 8mhz 286.

-- 
Kaleb Keithley                      Jet Propulsion Labs
kaleb@thyme.jpl.nasa.gov

6500spyk@ucsbuxa.ucsb.edu (Chris Brooks) (11/13/90)

In article <1990Nov12.221845.21901@icad.com> crm@icad.com (Christopher McConnell) writes:


>I asked this question before, and I received only one reply, which was
>to go all the way and install a new 386 motherboard.  What I really want
>to know is, how does one 'push' their CPU to a faster speed?  Is it just
>changing the crystal, or is there anything more to it?

The answer is yes, there is more to it.  I'm no expert, but it is more than
just the crystal that determines how fast your system will run.  For one,
your 80286 is probably not rated for speeds higher than 8MHz or so.  Also,
your RAM may not be able to keep up with a higher clock speed (without
inserting wait states).  So it is a pretty significant chore to speed it up
(unless of course you know that everything on board can keep up...)


--
Christopher L. Brooks                               6500spyk@ucsbuxa.bitnet
UC - Santa Barbara                                  brooks@faulty.ucsb.edu

phil@brahms.amd.com (Phil Ngai) (11/14/90)

In article <1990Nov12.221845.21901@icad.com> crm@icad.com (Christopher McConnell) writes:
|I asked this question before, and I received only one reply, which was

Fine, here's a reply from a person who designs hardware for a living.
(but doesn't make any money based on whether or not you push your
mother)

|to go all the way and install a new 386 motherboard.  What I really want
|to know is, how does one 'push' their CPU to a faster speed?  Is it just

The answer is: YOU DON'T. If the vendor could have made the system
run reliably at a faster speed, don't you think he would have?
If you don't care whether your system runs reliably, then I think
you're misguided.

|changing the crystal, or is there anything more to it?

Yes, there is more, a lot more. What would you have to do to make
your car fly? Would you put a propeller on it? Oh, don't forget
the wings. New landing gear?

Your microprocessor is probably not rated to run faster than it's
going now. Your memory is also not rated to run faster. Your memory
control logic is not rated to run faster. Your interrupt controller,
DMA controller, timer chips etc...

So the guy who told you to replace your motherboard is right.

--
KristallNacht: why every Jew should own an assault rifle.

2113av@gmuvax2.gmu.edu (John Porter) (11/18/90)

"KristallNacht: why every Jew should own an
 assault rifle." <- why everyone else should own an assault rifle.