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From: "Brian G. Lucas" <bagel99@gmail.com>
Newsgroups: comp.arch
Subject: Re: The Seymour Cray Era of Supercomputers
Date: Mon, 26 May 2025 11:48:13 -0500
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On 5/19/25 2:14 PM, 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).
> 
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).

Brian


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