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

Function of the card:
CTDL-Coupling Network
CTDL - Coupling Network
CM to CTDL Coupling Network

Listed in 1401 SMS card usage

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

Part number: 371256

Used in: IBM 1410, IBM 7070, IBM 1401

Cap code: None (details)

Symbol: R

R: Load. Provides proper terminating impedance or optimum coupling of one circuit to another at the correct operating voltage level.
IBM SMS card type CM 371256 IBM SMS card type CM 371256

Image courtesy of Christoph Methfessel

References: IBM Standard Modular System, Component Circuits, p49
1410_SMS_VOL_2.pdf, p70
1_2 SMS Cards, p102
Coslet data

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.