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From: bcase@amdcad.UUCP (Brian case)
Newsgroups: net.arch,net.micro
Subject: First PC/RT benchmark!!
Message-ID: <8645@amdcad.UUCP>
Date: Thu, 23-Jan-86 21:19:14 EST
Article-I.D.: amdcad.8645
Posted: Thu Jan 23 21:19:14 1986
Date-Received: Fri, 24-Jan-86 22:12:00 EST
Organization: AMDCAD, Sunnyvale, CA
Lines: 51
Keywords: benchmark, PC/RT, RISC
Xref: watmath net.arch:2426 net.micro:13581

Ok, guys, here it is:  the first "benchmark" of the NEW, improved,
whiter, brighter, IBM PC/RT.  This is the guy with the ROMP RISC
processor in it.  We saw one at the IBM Palo Alto Engineering
Support Center.  It seems ok, but I personally hate system V UNIX.
We ran the famous while loop benchmark:

main ()
{
    register int i;
    for (i = 0; i < 1000000; ++i)
	;
}

Now, the compiler invoked by the cc comand, even with the -O
option, produced the most awful code I have ever seen.  So,we
edited the .s file and made the loop only 3 instructions:

L.15:
	c	5,0
	bltx	L.15
	sis	5,1

(Note the use of the delayed branch.)  I can't quite remember if the
increment was called sis or six, but whatever.  The compiler -O
produced a 6 instruction sequence with two branches, etc.  Yeech.

Well, the hand-optimized version runs in 1.5 secs (user).  On a
Vax 780, the cc -O version (compiles to one instruction) runs in
1.9 secs.  The RT cc -O (i.e., without hand-optimization) version
ran in 1.8 secs.  So, the RT looks to be indeed faster than a 780,
but by just how much we will not know until definative benchmarks
(like drystone (:-) are run.  Looks like a good box for the price.

We saw the low-res screen, but it was interlaced and had a very
good appearance.  We saw an automatic demo of a Mac-like editor
and the fonts and windows were very user-inviting.  I didn't like
the fact that IBM chose not to go with the tactile-feedback-type
of keyboard that they are famous for (IBM 3101, PC, 3270, etc).
We also tried another experiment:  we forked off 11 infinite loop
processes and then tried some vi and ps.  The machine still seemed
to have reasonable response to vi commands like 'j'.  They also
had a 5080 graphics substation on display, but not connected to 
the RT.  It is nice, I guess, but is HUGE compared to the RT.  I
tend to think that using an AT color graphics card and a small
monitor may be the way to go (unless the 5080 can turn somersaults
or something).

Does anyone know if the C compiler we used was indeed the one
written for the RT by Tartan Labs???

    bcase