Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Posting-Version: version nyu B notes v1.5 12/10/84; site acf4.UUCP
Path: utzoo!linus!philabs!cmcl2!acf4!tsc2597
From: tsc2597@acf4.UUCP (Sam Chin)
Newsgroups: net.micro
Subject: Re: AT vs Z-100 - a myth
Message-ID: <1040026@acf4.UUCP>
Date: Thu, 30-May-85 15:35:00 EDT
Article-I.D.: acf4.1040026
Posted: Thu May 30 15:35:00 1985
Date-Received: Sat, 1-Jun-85 12:25:48 EDT
References: <1040024@acf4.UUCP>
Organization: New York University
Lines: 38

<>

Some how I don't seem to be getting through!

(1) We were comparing and 8088 vs a 80286. We were not comparing a 8087 to
an 80287. No one ever mentioned benchmarks with the floating point
processors until someone from Caltech posted those benchmark times. It is
entirely true that a 4 Mhz 80287 (used on the AT) will be slower than an 8
Mhz 8087 (used on a Hudson board for example) but virtually all 8086
instructions will be faster on a 80286. Without even running benchmarks,
just look at the 80286 spec to see how many cycles are required for the
various instructions and then compare it to the 8088 spec. You will find out
that the 80286 requires less cycles for virtually all instructions. I think
I am just restating the obvious.

(2) What I can tell you about memory wait states is that my 2 256K RAM
boards from Lomas Data Products are loaded with 150ns RAMS. I have wire
wrapped exactly 1 wait state on a memory cycle and 2 wait states on i/o
cycles on the CPU board which has a 8 Mhz 8086. If I remove the wait state
on the memory cycle, the system occasionally hangs. The manual clearly
states that if I use a 8086 CPU above 5 Mhz, I have to enable the r/w 
acknowledge signal and enable the wait state on the memory cycle. It might
be possible that the 8088 is sufficiently slower than the 8086 that the wait
state is not necessary but then the 80286 is still faster than the 8086.

(3) My benchmark with generic MS-BASIC on the AT proves that the AT is
faster than an 8 Mhz 8086 running with 100ns static ram *even* with its one
wait state. The original BASIC benchmark didn't make sense because you were
not using the *exact* same basic interpreter. People all over the net
reported wildly varying times when they ran the benchmark on their own
versions of Microsoft Basic on their own machines.

Will someone from Intel get into this and clear this up. We are not
comparing uP from different companies.

Sam Chin
allegra!cmcl2!acf4!tsc2597
tsc2597.acf4@nyu