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From: mitchalsup@aol.com (MitchAlsup1)
Newsgroups: comp.arch
Subject: Re: The Seymour Cray Era of Supercomputers
Date: Mon, 26 May 2025 18:01:56 +0000
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On Mon, 26 May 2025 16:48:13 +0000, Brian G. Lucas wrote:

> 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).

Candidates:: RTL, DTL, CML

>                                                   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.