🚀 go-pugleaf

In article <900302202...@en.ecn.purdue.edu> zaw...@EN.ECN.PURDUE.EDU
(Paul J Zawada) writes:

>> Not strictly true.  A common modification on the old IBM PCs is
>> to replace the 8088 with a NEC V-20 or similar ship and the crystal
>> with a faster one.  Thus a 4.77MHz machine might clock up to 8Mhz or
>> more instead.  This modification costs about $20.  

> Well... This doesn't always completely work....  Sure, you can replace an
> existing processor and crystal with a faster combination, but all you are
> doing is increasing the speed of the bus clock, which can cause more
> problems.  If the rest of the circuitry (logic, memory, etc.) in the computer
> can't handle the faster speed, the processor will end up sitting
> idle waiting on the rest of the computer.  (At the very least...)

Well, I agree with the thrust of what Paul is saying, but...

There seems to be a general misunderstanding extant that the memory chips
somehow tell the processor what speed they are, and can slow down the CPU.
** THIS IS NOT TRUE **

The CPU puts the address up, then some time later that only depends on the
CPU's internal timing it samples the data lines.  IF THE MEMORY WAS TOO SLOW
AND DIDN'T GET THE DATA UP IN TIME, TOUGH NOOGIES, *NOBODY NOTICES*!!!

That means you get *Bad Data* and your application crashes or prints absurd
numbers at you.


Sooo...  The CPU does *NOT* "sit idle waiting on the rest of the computer".
It really does go faster!  And produces nonsense data or crashes out.

Nuf Sed?

-- 
Sig     DS.L    ('ZBen')       ; Ben Cranston <zb...@Trantor.UMD.EDU>
* Network Infrastructures Group, Computer Science Center
* University of Maryland at College Park
* of Ulm