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

Function of the card:
SDTDL - trigger

Saturated Drift Transistor Diode Logic (SDTDL) is a form of Diode-transistor logic using faster drift-field transistors.

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

Part number: 370222

PCB number: 484033

Used in: IBM 1311 Disk, IBM 1410


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 DEM 370222 IBM SMS card type DEM 370222

References: 1410_SMS_VOL_1.pdf, p39
IBM 1311 ILD, p115
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.