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

Function of the card:
Two of Five Validity Check Circuit

Part number: 371504

Used in: IBM 7070

Symbol:VCK

VCK: Validity Check. Used for checking information bits in the 2-of-5 bit code system.

References: IBM Standard Modular System, Component Circuits, pp120,121,122
This page created by Ken Shirriff on Wed Sep 15 18:15:11 2021.

The information on these pages comes from a variety of sources, especially old IBM documents on bitsavers.org, 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.