The Standard Modular System (SMS) is a system of standard

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ized circuit boards and mounting racks developed by IBM in the late 1950s, originally for the

IBM 7030 Stretch The IBM 7030, also known as Stretch, was IBM's first transistorized supercomputer. It was the fastest computer in the world from 1961 until the first CDC 6600 became operational in 1964."Designed by Seymour Cray, the CDC 6600 was almost three tim ...

. They were used throughout IBM's second-generation computers, peripherals, the

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, the 1400 series, and the

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. SMS was superseded by

Solid Logic Technology Solid Logic Technology (SLT) was IBM's method for hybrid packaging of electronic circuitry introduced in 1964 with the IBM System/360 series of computers and related machines. IBM chose to design custom hybrid circuits using discrete, flip chi ...

(SLT) introduced with

System/360 The IBM System/360 (S/360) is a family of mainframe computer systems that was announced by IBM on April 7, 1964, and delivered between 1965 and 1978. It was the first family of computers designed to cover both commercial and scientific applica ...

in 1964, however they remained in use with legacy systems through the 1970s.

Overview

Many IBM peripheral devices that are part of System/360, but were adapted from second-generation designs, continued to use SMS circuitry instead of the newer SLT. These included the 240x-series tape drives and controllers, the 2540 card reader/punch and 1403N1 printer, and the 2821 Integrated Control Unit for the 1403 and 2540. A few SMS cards used in System/360 peripheral devices even have SLT-type hybrid ICs mounted on them ''(see right)''. SMS cards are constructed of individual

discrete component An electronic component is any basic discrete device or physical entity in an electronic system used to affect electrons or their associated fields. Electronic components are mostly industrial products, available in a singular form and are not ...

s mounted on single-sided paper-epoxy

printed circuit board A printed circuit board (PCB; also printed wiring board or PWB) is a medium used in Electrical engineering, electrical and electronic engineering to connect electronic components to one another in a controlled manner. It takes the form of a L ...

s. Single-width cards are 2.5 inches wide by 4.5 inches tall by 0.056 inches thick, with a 16-pin

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edge connector An edge connector is the portion of a printed circuit board (PCB) consisting of traces leading to the edge of the board that are intended to plug into a matching socket. The edge connector is a money-saving device because it only requires a sing ...

. Double-width cards are 5.375 inches wide by 4.5 inches tall, with two 16-pin gold plated edge connectors. Contacts are labeled ''A–R'' (skipping ''I'' and ''O'') on the first edge connector, and ''S–Z, 1–8'' on the second. The cards are plugged into a card-cage back-plane and edge connector contacts connected to

wire wrap Wire wrap is an electronic component assembly technique that was invented to wire telephone crossbar switches, and later adapted to construct electronic circuit boards. Electronic components mounted on an insulating board are interconnected by l ...

pins. All interconnections are made with wire-wrapped connections, except for power bus lines. The back-plane wire-wrap connections were mostly made at the factory with automated equipment, but the wire-wrap technology facilitated field-installation of engineering changes by customer engineers. Some card types can be customized via a "program cap" (a double-rail metal jumper bar with 15 connections) that could be cut to change the circuit configuration. Card types with a "program cap" came with it precut for the standard configuration and if a customer engineer needed a different configuration in the field he could make additional cuts as needed. This feature was intended to reduce the number of different card types a customer engineer had to carry with him to the customer's site. The card type is a two- to four-letter code embossed on the card (e.g., ''MX, ALQ''). If the card has a "program cap" the code is 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 Digital usually refers to something using discrete digits, often binary digits. Technology and computing Hardware *Digital electronics, electronic circuits which operate using digital signals **Digital camera, which captures and stores digital i ...

logic families In computer engineering, a logic family is one of two related concepts: * A logic family of monolithic digital integrated circuit devices is a group of electronic logic gates constructed using one of several different designs, usually with compati ...

were implemented (ECL, RTL, DTL, etc.) as well as

analog circuit Analogue electronics ( en-US, analog electronics) are electronic systems with a continuously variable signal, in contrast to digital electronics where signals usually take only two levels. The term "analogue" describes the proportional relati ...

s, to meet the requirements of the many different systems in which the cards were used. File:IBM SMS card component side.jpg, SMS card from an IBM 1401 File:IBM SMS card circuit side.agr.jpg.jpg, Circuit side of same SMS card File:IBM SMS card, front.jpg, SMS card, front File:IBM SMS card, back.jpg, SMS card, back File:SMS card with power transistors.jpg, SMS card from an IBM 1401 File:IBM 1401 card cage 2.agr.jpg, IBM 1401 card cage File:IBM 1401 backplane.jpg,

Wire wrap Wire wrap is an electronic component assembly technique that was invented to wire telephone crossbar switches, and later adapted to construct electronic circuit boards. Electronic components mounted on an insulating board are interconnected by l ...

ped

backplane A backplane (or "backplane system") is a group of electrical connectors in parallel with each other, so that each pin of each connector is linked to the same relative pin of all the other connectors, forming a computer bus. It is used as a backbo ...

the same 1401 card cage File:IBM 7070.jpg, IBM 7070 card cage

References

External links

Customer Engineering Instruction-Reference, Standard Modular System
PDF

*http://ibm-1401.info/index.html ** http://ibm-1401.info/IBM-StandardModularSystem-Neff7.pdf
IBM SMS Cards Database
{{DEFAULTSORT:Standard IBM computer hardware IBM 700/7000 series IBM 1400 series

Overview

See also

References

External links