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

Function of the card:
U to T Converter (4 loads)
Ctdl-one way npn four loads
CTDL-One Way NPN Four
Ctdl-one way npn
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 1410, IBM 1414 I/O Synchronizer, IBM 1401, IBM 7070

Cap code: ZV (details)

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

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.