Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!utgpu!water!watnot!watmath!clyde!rutgers!pyrnj!mirror!cca!dvmark
From: dvmark@cca.UUCP
Newsgroups: comp.sys.amiga
Subject: Re: MIPS, Turbo Amiga, Mac II
Message-ID: <13928@cca.CCA.COM>
Date: Sat, 14-Mar-87 00:38:27 EST
Article-I.D.: cca.13928
Posted: Sat Mar 14 00:38:27 1987
Date-Received: Sun, 15-Mar-87 07:40:48 EST
References: <12284247071.70.PKG.SPARKMAN@MCC.COM>
Reply-To: dvmark@CCA.UUCP (Mark Jay Jones)
Organization: Computer Corp. of America, Cambridge, MA
Lines: 39

Don't feel bad, there is much confusion about MIPS.  I have had to deal with
this for 15 years (notice my gray beard showing :^)= ).  IBM use to quote 
Millions of Instructions Per Second ratings on new machines years ago.  They
*ACTUALLY* sampled some real user's old 360 mainframes and got a standard
mix of instructions to use as a standard benchmark for IBM machines.  The
instruction set chosen contained a mix of binary arithmetic, address 
manipulation, character handling (strings to you C kind of guys) and packed
decimal arithmetic.  These were really good benchmarks, and gave useful
MIPS ratings within the IBM mainframe line.  

However, competition killed the good benchmark.  Sadly, IBM refuses to run
their standard benchmark on newer machines.  What happened is that some
mainframe competitors started running benchmarks with NOPs in a loop and 
reported twice the MIPS of IBM's machines (though the IBM machines were
really faster).  This is like deja-vu with the INTEL 80386 claim of 3-4 MIPS
(really NOPs) better than 68020 (running a good instruction set mix).

IBM's official line is:  MIPS stands for Meaningless Indicator of Performance.
IBM refuses to quote MIPS anymore.  Anyone can create a benchmark that favors
their machine and beat someone else's honest MIPS rating taken to try to 
explain to customers how much faster the new machine is than the old one.

To help answer the question, assuming the same bus width (16 or 32 bits), and
that all parts of the system are upgraded in step (if your CPU is running 
faster, you better have memory that doesn't hold up the CPU), a 14 mhz machine
will be twice the speed of a 7 mhz machine.  This only applies to an identical
hardware architecture.  The Amiga has hardware assists (in it's custom chips)
for some heavily CPU intensive stuff like graphics and sound that the Mac has
to do all in software.  That is why equivalent benchmarks on the 7.14 mhz
Amiga are better than the 8 mhz Mac.  The Mac has a different architecture
than the Amiga, so comparing mhz rating is not useful.  About all you can
say is that X architecture running at double the mhz of the old X architecture
should run twice as fast.  I am not going to go into cacheing, pipelining
and fancy stuff being done in the CPU to make them faster (like the 68000 vs
the 68020), read the 68k news group for that stuff.

_____
I wrote this with 3D glasses on, could you tell?