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

Function of the card:
CTDL- “T” Line Latch

Listed in 1401 SMS card usage

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

Part number: 370357

PCB number: 493115

Used in: IBM 1401

IBM SMS card type CEM 370357 IBM SMS card type CEM 370357

Image courtesy of Randall Neff

References: Coslet data
1_2 SMS Cards, p81
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.