Re: [Fwd: starship-design: HIGHLY OPTIMIZED TOLERANCE]

[Steve VanDevender <stevev@efn.org>]

STAR1SHIP@aol.com writes:
 > In a message dated 3/23/00 7:10:59 AM Pacific Standard Time, 
 > lparker@cacaphony.net writes:

 > > On the reuse topic, you should look inside an electronic typewriter. The
 > >  "cpu" is an Z80!
 > >  
 > >  Lee

 > Lee,
 > Since the CPU chip used in the first PC's, was one of the many parallel 
 > processing chips of the early super computers. All CPU chips today still 
 > contain the lead input/output pins for connecting in series or parallel with 
 > other chips. In one case I used a Novel network board connected to these 
 > lead-in pins and wired many (100) used complete XT (Z-80 chip if my memory 
 > serves) and AT CPU's in parallel. It worked well and passed the "smoke test" 
 > :=). As used and new 386, 486 and pentium CPUs became available the CPU's 
 > were changed out.

Tom, you're making stuff up again.

The 8080, Z-80, 8086/8088, and 80286 don't have any intrinsic support
for hardware synchronization to allow multiple CPUs to share memory or
other peripherals in the same system.  People built external logic for
processors of that period to support multi-CPU systems with shared
memory and peripherals, but you can't just directly hook together the
only the microprocessor chips themselves and have it work.  In fact, it
makes no sense talking about wiring together the kinds of processors
you're talking about either in series or in parallel.  Even modern
microprocessors with intrinsic support for multi-CPU systems require
some external logic for things like bus arbitration and interrupt
handling.

Neither are "early supercomputers" that similar to microprocessors;
depending on how far you go back, earlier computer designs didn't use
integrated circuits at all or used a quantity of much simpler ICs to
implement the CPU.  Few of these designs supported multiple CPUs with
shared access to common memory or peripherals either.  When they did the
designs were architecturally very different from modern microprocessors.

There are certainly computing tasks where one can use a lot of
individual complete computer systems operating in parallel, but it's not
nearly as easy as soldering a stack of Z-80s together.