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

Function of the card:
CTDL-Extender Card
Extender and Limiter Card

Listed in 1401 SMS card usage

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

Part number: 371255

Used in: IBM 1401, IBM 7070

Cap code: VQ (details)

Symbol: E

E: Extender. Provides additional inputs to logical blocks and triggers. Adds to drivers the ability to drive more loads.
IBM SMS card type CLVQ 371255 IBM SMS card type CLVQ 371255 IBM SMS card type CLVQ 371255 IBM SMS card type CLVQ 371255

Image courtesy of Randall Neff

References: 1_2 SMS Cards, pp35,98
IBM Standard Modular System, Component Circuits, p48
Coslet data
SMS Cap Code Templates & Index

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.