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

Function of the card:
CTDL-High Speed 3-Way “And” No Loads
Three-Way -AND (no loads)

Listed in 1401 SMS card usage

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

Part number: 371586

Used in: IBM 1401, IBM 7070


-A: Negative AND. In-phase output is negative only when all inputs are negative. Out-of-phase output is positive for the above condition.

References: 2_2 SMS Cards, p28
1_2 SMS Cards, p40
Coslet data
IBM Standard Modular System, Component Circuits, p159
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, 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.