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

Function of the card:
Ctdl-one way pnp
CTDL-One Way PNP 4 Loads Four on Card
T to U Converter (4 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: 371271

PCB number: 491441

Used in: IBM 1401, 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 CQZV 371271 IBM SMS card type CQZV 371271 IBM SMS card type CQZV 371271 IBM SMS card type CQZV 371271 IBM SMS card type CQZV 371271 IBM SMS card type CQZV 371271

Image courtesy of Randall Neff

References: Coslet data
1_2 SMS Cards, pp37,110
IBM Standard Modular System, Component Circuits, p54
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.