Standard Modular System: Difference between revisions

Revision as of 00:29, 18 March 2018

Revision as of 00:31, 18 March 2018

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The card type was a two- to four-letter code embossed on the card (e.g., ''MX, ALQ''). If the card had a "program cap" the code was split into a two-letter card type code and a two-letter "cap connection" code (e.g., ''AK ZZ'').

When SMS was originally developed, IBM anticipated a set of a couple hundred standard card types would be all that would be needed, making design, manufacture and servicing simpler. Unfortunately that proved far too optimistic as the number of different SMS card types soon grew to well over 2500. Part of the reason for the growth was that multiple [[Digital data|digital]] [[logic families]] were implemented (ECL, RTL, DTL, etc.) as well as [[analog circuit]]s, to meet the requirements of the many different systems in which the cards were used in.

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