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

Function of the card:
CTDL-Trigger No 2
CTDL Trigger 2

Listed in 1401 SMS card usage

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

Trigger is IBM's term for a flip flop or latch.

Part number: 371082

Used in: IBM 1401, IBM 7070


T: Trigger. A conditioned bi-stable device whose steady-state outputs change from one stable state to the other with two separate triggering levels, pulses, or voltage changes. The set input turns the trigger on if the reset input Is not on, and vice versa.
IBM SMS card type JZ 371082 IBM SMS card type JZ 371082

Image courtesy of Randall Neff

References: 2_2 SMS Cards, pp39,40
Coslet data
IBM Standard Modular System, Component Circuits, pp164,165
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, 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.