🚀 go-pugleaf

>In article <TMH.92Aug26230950@doppel.first.gmd.de> tmh@doppel.first.gmd.de (Thomas Hoberg) writes:
>>In article <BtLGIG.3q2@pgroup.com> I write:
>>   Actually, the announcement was that Intel had admitted the failure of
>>   the i860 as a general-purpose CPU.  They still intend to support it in
>>   graphics and embedded applications; speculation is that they will also
>>   support it for the iPSC MPP systems.  No followon has been announced,
>>   but one would obviously be needed if they do indeed plan to continue to
>>   use i860-like chips in the iPSC.
>>
>>Why did it fail, though? While there might be better CPUs today, I
>>thought it pretty good when it came out. Was there anything seriously
>>wrong with it (except that it'd do virtual caching)? Was it just that
>>the various vendors were too busy promoting their own designs or
>>tuning their old architectures? Is it just bad luck that nobody
>>decided to pick it up or is there something about the i860 that I
>>missed?
>

My guess is that it is not a superscalar design. The chip relies heavily
of the code generating all the pipe lining. This makes  compiler
writing difficult (right Larry?). It makes assembly coding difficult.
It leads to slower nominal performance rates. While an i860 is very fast
on an infinitely long vector:vector operation (100 mflop @ 50 M) for 
floating point that doesn't vectorize, it is less than blazing. 

Superscalar designs also handle concurrent execution of different processing
units alot nicer. 

So, if INTEL took an i960 core, expanded it to 64 bits wide, mix in floating
point, of i860 speeds, with out that damned pipelining by hand stuff, 
had some SHARED registers between the floating point
and integer sections, did speculative instruction execution on the alu and
fpu, provided a 64 bit alu which ops could be segmented into 
2*32, 4*16, or 8*8 bit concurrent 2's compliment operations, AND ALLOWED THE
ENTIRE DATA CACHE TO BE BOOT TIME SELECTABLE AS EITHER DATA CACHE OR MEMORY
MAPPED FAST DATA STORAGE, I'd be happy, and I think it would sell, IMHO. 

-Rich

rstewart@megatek.com