From: utzoo!decvax!ucbvax!C70:info-cpm
Newsgroups: fa.info-cpm
Title: [cdh: IBM PC Benchmark]
Article-I.D.: ucb.1084
Posted: Sat May 15 00:51:31 1982
Received: Sun May 16 00:29:54 1982

>From W8SDZ@Mit-Mc Sat May 15 00:51:16 1982
Date: 13 May 1982 18:18:53 EDT (Thursday)
From: Carl D. Howe 
To:   decvax!harpo!duke!hes at Berkeley
cc:   info-micro at mit-ai
Re:   IBM PC Benchmark

        From: decvax!harpo!duke!hes at Berkeley

	....

        " Since the IBM PC is supposed to have its 8088 running with
        a 4.88 (?) MHz clock, it would appear that the present
        generation of IBM PC software does not take advantage of the
        internal 16 bit architecture of the 8088.  (Or perhaps is
        just not as efficient as some older, more polished software.)"

I suspect that the current generation of IBM software uses the 16 bit
architecture of the 8088 extensively, and therein lies the performance
problem.  When you assume that 16 bit operations are the right thing
ON AN 8-BIT BUS, you end up doing a lot of back-to-back bus
cycles, many of them needlessly.  If IBM was using an 8 bit bus that 
was capable of doing twice as many transactions per second as the rest 
of the industry, then the 16 bit architecture would be a big performance 
improvement.  As it is, the fact that the machine has an 8 bit bus and
runs it at a comparable speed to all the rest of the 8 bit machines dictates
that the machine has the performance of an 8 bit micro.

In short, chip architecture performance is often dominated by how fast 
you can get items into and out of memory.  You should view the use of an
8088 in the IBM PC as a feature to aid software development,
not as a feature to improve performance.  The IBM PC is still an 8 bit micro,
despite the 8088's 16 bit architecture.

Carl