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

Function of the card:
CTDL -N “Or” 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: 371074

PCB number: 528999

Used in: IBM 1401, IBM 7070


E: Extender. Provides additional inputs to logical blocks and triggers. Adds to drivers the ability to drive more loads.
IBM SMS card type CLVS 371074 IBM SMS card type CLVS 371074

References: Coslet data
1_2 SMS Cards, pp35,100
This page created by Ken Shirriff on Wed Sep 15 18:15:11 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.