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

Function of the card:
SDTDL trigger and driver
Trigger and Driver
Trigger and driver

Listed in 1401 SMS card usage

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: 370350

Customer Eng reference number: 729925

PCB number: 484127

Used in: IBM 1410, IBM 1311 Disk, IBM 1401, IBM 1443 Printer, IBM 2821 Control Unit, 7040

Cap code: None (details)

Symbol: T

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 DHF 370350 IBM SMS card type DHF 370350 IBM SMS card type DHF 370350 IBM SMS card type DHF 370350

References: IBM 1443 ALD, p103
IBM 2821 CCD, p59
IBM 1311 ILD, p127
2_2 SMS Cards, p101
1410_SMS_VOL_1.pdf, p89
Coslet data

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.