Re: AS/400 on Intel?? - Very Long! -- MIDRANGE-L

This question was posed to Frank Soltis at a presentation he did back in May and
this is his response (paraphrased):

When it was uncertain whether IBM management would invest the significant sum of
money needed to continue development of the Power PC processor line, the
Rochester lab evaluated porting the System Licensed Internal Code to both the
Alpha architecture (it being the only other 64 bit chip at the time) as well as
to the Intel Merced/Itanium.

Dr. Soltis felt that Alpha would run out of steam about the same time as Power 
PC
and that neither Digital Equipment (at the time) or now Compaq were going to 
make
the huge investment required to keep it state of the art so Intel was the likely
winner if Power PC were dropped.

The trouble is, the Intel chip architecture suffers major performance hits when
doing the kind of standard I/O activities that commercial servers do. It's fine
for mathematical benchmarks and the engineers at Intel have done an amazing job
with graphic stuff BUT that isn't what AS/400's do for a living. AS/400's do a
bazillion calls to memory and disk I/O's. The Intel architecture hits the wall
VERY fast in that kind of activity. In addition the interface between memory and
processor in the Intel schema is VERY slow compared to current Power PC
processors.

When IBM management committed to funding further Power PC development out to
about 2003 (which is as far as can realistically be prognosticated), Rochester
chose to stay with what it knew as well as what it believed was the best
price/performance architecture.

----end of Dr. Soltis's comments----

In my own opinion, it helps that Dr. Soltis has had significant influence in the
design of the later Power PC iterations (if not all of them perhaps). He has 
been
able to get design tweaks that have been very helpful for achieving the kind of
performance a virtual machine architecture (like AS/400) needs to stay
competitive. It's my understanding (somebody correct me if I misunderstood Dr.
Soltis) that the newest generation Power PC just put into the RS/6000 and coming
out in the next generation of AS/400 is identical except for some switches set 
in
microcode that tell it whether it's an AS/400 or not. That means that floating
point calcs on the AS/400 would execute about as fast as on an RS/6000. Not that
you'd buy an AS/400 to model nuclear explosions but that would make applications
which deal with floating point calcs (Java, C++, etc.) much faster versus today.
This seems to be confirmed by the latest Midrange Computing Monday Morning 
Update
previously referred to.

Randy Mangham
Pacific Crest Consulting
San Diego, CA

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