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

Function of the card:
Ctdl 3 way and npn field replacement
Three-Way +AND (no loads)

CK is listed in some sources with part number 371270, which corresponds to CKWF.

Complemented Transistor Diode Logic (CTDL) is IBM's term for a form of diode-transistor logic.

Field replacement part number: 370978

Used in: IBM 1401, IBM 7070


+A: Positive AND. in-phase output is positive only when all inputs are positive. Out-of-phase output is negative for the above condition.
IBM SMS card type CK IBM SMS card type CK

Image courtesy of Henk Stegeman

References: IBM Standard Modular System, Component Circuits, p46
This page created by Ken Shirriff on Wed Sep 15 18:15:10 2021.

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.