Re: The Seymour Cray Era of Supercomputers

On 5/19/25 2:14 PM, MitchAlsup1 wrote:

On Mon, 19 May 2025 13:35:37 +0000, Michael S wrote:
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On Sun, 18 May 2025 22:01:19 +0000
mitchalsup@aol.com (MitchAlsup1) wrote:
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On Sun, 18 May 2025 8:33:30 +0000, Michael S wrote:
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On Sat, 17 May 2025 21:27:04 +0000
mitchalsup@aol.com (MitchAlsup1) wrote:
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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 ??
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During the CDC 7600 reign, when performing vector calculations,
(even though CDC 7600 was not a vector machine, it could stream
calculations through its execution window at impressive rates);
Certain data bit-patterns in CDC 7600 would cause more Gnd bounce
and Vdd drop than the gates cols accommodate and the machine would
take a data-dependent hard crash.
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Which voltage, current and frequency are we talking about?

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Vdd and Gnd which fed the integrated logic gates.
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My question was about absolute numbers. Volts, amperes, nanoseconds.

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CDC 6600 was built with (effectively) RTL logic using individual parts
{transistors, resistors, capacitors, ...} well documented in "design
of a computer" Thornton.
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CDC 7600 was built with some kind of integrated circuits, but not
TTL or ECL. I don't remember which (its been too long).
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Could it have been DTL (Diode-Transistor-Logic).

                                                  In 1966 I worked
on an aerospace computer implemented with DTL, in flatpacks made
by Westinghouse (could that be?).  The computer was interesting
in that it had sine and cosine instructions (implemented by the
cordic algorithm).
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Brian
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So, Cray got rid of the problem by presenting a DC-load to the
power supply.