Re: The Seymour Cray Era of Supercomputers

On Sun, 18 May 2025 15:23:03 +0000, Michael S wrote:

On Sun, 18 May 2025 05:46:37 -0000 (UTC)
Thomas Koenig <tkoenig@netcologne.de> wrote:
>

MitchAlsup1 <mitchalsup@aol.com> schrieb:

Did the book relate the story of why CRAY-1 presented a DC-load to
the power supply:: that is, the ECL gates were all of the form where
they would switch 20 ma into either the true or the complement out-
put and thus have no AC energy at the power supply level ??

>
That they didn't mention.  They stressed his decision to build
a machine which had good all-round performance, unlike the
predecessors like the STAR or the Texas Instruments ASC (which I
had never heard or read of).
>

>
May be, that aspect of CRAY-1 was different from STAR and ASC, but not
different from CDC 6600 or 7600 or from top models of Cyber-170 series.

CRAY-1 was relatively fast running scalar while ASC and STAR were not.

There was one part on the Cray-I design that I found weird.  After
writing that individual transistors would have been faster than
integrated circuits, but were chosen for density and manufacture,
they wrote
>

>
That part sounds correct. Logic ICs used in Cray-1 were indeed slower
than contemporary individual transistors.
>

"Concerning memory, as in the case of the CPU, Cray did not
choose the fastest individual components, which would have
been magnetic cores" due to their limitations in size.
>

>
That part does not sound right. CRAY-1  main memory was made of SRAM
with 48 ns access time. That was 4-5 times faster than contemporary
core memories. Plus, it didn't suffer from destructive read.
One part that is true is that faster and less dense memory components
were available, but they were SRAM as well.
>

What they also describe well is the tradeoff between different
vector lengths.  Also very interesting is the mechanisms of getting
the machines adopted by different industries.