Path: utzoo!attcan!uunet!bu.edu!rpi!zaphod.mps.ohio-state.edu!sdd.hp.com!ucsd!ucbvax!husc6!spdcc!esegue!johnl
From: johnl@esegue.segue.boston.ma.us (John R. Levine)
Newsgroups: comp.arch
Subject: Re: Moto's data predicts 68040 performance well below 20 MIPS
Message-ID: <1990Jul18.231251.7279@esegue.segue.boston.ma.us>
Date: 18 Jul 90 23:12:51 GMT
References: <40088@mips.mips.COM> <14900009@hpdmd48boi.hp.com> <13266@cbmvax.commodore.com> <40231@mips.mips.COM> <13286@cbmvax.commodore.com>
Reply-To: johnl@esegue.segue.boston.ma.us (John R. Levine)
Organization: Segue Software, Cambridge MA
Lines: 23

In article <40231@mips.mips.COM> paulr@mips.COM (Paul Richardson) writes:

>And do not forget that the Vax 11/780 is technically not a 1 mips machine.
>The clock cycle is 200ns.

Depends what you mean by MIPS, other than the accurate Meaningless Index of
Processor Speed.  It's true, a 780 typically executes about 600K instructions
per second.  The 1 MIPS figure came about when someone observed that the 780
is about as fast as an IBM mainframe (370/158?) that was rated 1 MIPS.
Evidently it accomplished somewhat more work per instruction than a 370 did.

IBM mainframes have been rated in MIPS for 25 years.  IBM 360/370 MIPS are
somewhat more meaningful than others since the comparison is among machines
that implement the same architecture and at least at first was calibrated to
reality, i.e. a 1 MIPS 360 was one that actually executed a million
instructions per second in some instruction mix.  It was also easier to do
such benchmarks on 360s since pesky things like caches and restartable string
moves didn't mess up the measurements.

-- 
John R. Levine, Segue Software, POB 349, Cambridge MA 02238, +1 617 864 9650
johnl@esegue.segue.boston.ma.us, {ima|lotus|spdcc}!esegue!johnl
Marlon Brando and Doris Day were born on the same day.