This page describes the IBM SMS card "HG", and is part of the SMS card database.

Function of the card:
Digit Read-In Driver

Part number: 371517

Used in: IBM 7070

Cap code: None (details)

Symbol: D

D: Driver. Isolates a signal from its generating source and uses it to drive one or more other circuits without affecting or overloading the generating circuits. Can be used to supply the required power directly or only to activate the circuit through which power is actually supplied.

References: IBM Standard Modular System, Component Circuits, p148

The information on these pages comes from a variety of sources, especially old IBM documents on, as well as information from the IBM 1401 restoration team, especially Tim Coslet's SMS data and Jim Hunt's data. Much of this information was obtained through OCR, so don't expect complete accuracy. These pages are not associated with IBM in any way.