Re: The Seymour Cray Era of Supercomputers

On Mon, 19 May 2025 18:14:17 +0000
mitchalsup@aol.com (MitchAlsup1) wrote:

On Mon, 19 May 2025 13:35:37 +0000, Michael S wrote:
 

On Sun, 18 May 2025 22:01:19 +0000
mitchalsup@aol.com (MitchAlsup1) wrote:
 

On Sun, 18 May 2025 8:33:30 +0000, Michael S wrote:
 

On Sat, 17 May 2025 21:27:04 +0000
mitchalsup@aol.com (MitchAlsup1) wrote:
 

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 ??
>
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.
 

>
Which voltage, current and frequency are we talking about? 

>
Vdd and Gnd which fed the integrated logic gates.
 

>
My question was about absolute numbers. Volts, amperes,
nanoseconds. 

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

I was wondering why the problem was not solved by improvement of
decoupling capacitors.

 

 

So, Cray got rid of the problem by presenting a DC-load to the
power supply.