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

Function of the card:
CTDL-Integrator – U and – T
Ctdl - integrator - u and - t
CTDL - Integrator _U and -T
Ctdl integrator u and t

Listed in 1401 SMS card usage

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

Part number: 371996

Used in: IBM 1401, IBM 1410, IBM 1414 I/O Synchronizer

IBM SMS card type NGXX 371996 IBM SMS card type NGXX 371996

Image courtesy of Randall Neff

References: 1410_SMS_VOL_2.pdf, p123
2_2 SMS Cards, p48
Coslet data
National Museum of Computing.
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.