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

Function of the card:
CTDL-Translate Block NPN
II to T Converter

Listed in 1401 SMS card usage

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

Part number: 371258

PCB number: 491003

Used in: IBM 1401, 7030, IBM 7070


C: Converter. Used to translate from one voltage level to another, or to change the amplitude of the voltage swing about the same reference level.
IBM SMS card type CNWU 371258 IBM SMS card type CNWU 371258

Image courtesy of Randall Neff

References: IBM Standard Modular System, Component Circuits, p51
Coslet data
1_2 SMS Cards, p104
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.