Xref: utzoo comp.sys.ibm.pc.hardware:3583 comp.sys.ibm.pc.misc:4372
Newsgroups: comp.sys.ibm.pc.hardware,comp.sys.ibm.pc.misc
Path: utzoo!utgpu!watserv1!ssingh
From: ssingh@watserv1.waterloo.edu (The Sanj - ISman (iceman))
Subject: Re: DTK Motherboards
Message-ID: <1990Dec5.015847.21620@watserv1.waterloo.edu>
Organization: University of Waterloo
References: <5714@crash.cts.com> <1990Nov20.180552.3474@cec1.wustl.edu>
Date: Wed, 5 Dec 90 01:58:47 GMT
Lines: 51

I have a question on DTK 386sx boards. I have a PPM 1630. I bought it 
in August of last year. I asked for 80 nanosecond RAMs. The board
is supposed to take 120 nanosecond RAMs. I was hoping for zero-wait-states.

When I saw that the Landmark rating was only 16 Mhz (not 18 or so), I started
asking questions.

I was told that the motherboard couldn't handle it.

Then I was told that I could get zero-wait-states by changing to the
latest BIOS. Supposedly DTK has only changed the BIOS to allow for
zero-wait-states.

Which brings me to the next question. I looked in Que's "Computer User's
Dictionary" (highly recommended) for the definition of wait state. It
said that these were "programmed into the system" to allow slower memory
to keep up with the CPU.

Presumably this means programmed into the BIOS. But it wouldn't work to
simply insert NOP (do nothing) instructions in the BIOS because the CPU
would be trying to execute the NOP instrutions themselves without any
slowdown. Finally, I came to the conjecture that since I have heard of
the idea of ROM shadowing on video cards to copy video BIOS into RAM for
faster execution, probably how wait states are implemented is that
using ROM chips causes enough of a slowdown to prevent timing problems.
This would cohere well with the idea of BIOS-shadowing offered by many
vendors of PC-compatibles.

First, is my reasoning correct?

Second, would using the latest version of DTK BIOS on a PPM 1630 with
80 nanosecond RAMS increase throughput? Does the latest version of
DTK BIOS allow BIOS shadowing? Does anyone have benchmarks available?

Lastly, what about operating systems like UNIX that bypass the BIOS
entirely, since all operations would be done in RAM, does this mean that
running UNIX would automatically yield better performance? If so, what
about timing problems, if I had used 120 ns. RAMs?

I know this is a barrage of questions, but I need help in this rather
important decision, and opinions, as you know are often contradictory.

Any assistance would be appreciated.

Ice.

-- 
"Weapon systems are L[+]CKED on you, Johnny-cake..."  
$anjay $ingh     Provost-Hunter     ssingh@watserv1.[u]waterloo.{edu|cdn}/[ca]
jwwong@a-provost: "I Come In Peace."	ssingh@watserv1: "You Go In Pieces."
"If this alt stuff makes you feel like shit, go to the john."-ssingh@watserv1