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

Function of the card:
Ctdl-one way npn
Ctdl-one way npn four loads
U to T Converter (4 loads)
CTDL-One Way NPN Four
CTDL - One Way NPN Four 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: 371274

PCB number: 491443

Used in: IBM 1401, IBM 1410, IBM 1414 I/O Synchronizer, IBM 7070

Symbol:C

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 CRZV 371274 IBM SMS card type CRZV 371274 IBM SMS card type CRZV 371274 IBM SMS card type CRZV 371274

Image courtesy of Randall Neff

References: 1_2 SMS Cards, p36
Coslet data
IBM Standard Modular System, Component Circuits, p55
1410_SMS_VOL_2.pdf, p74
National Museum of Computing.
2_2 SMS Cards, p3
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 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.