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

Function of the card:
SDTDL and SDTRL 3K Resistor Load
SDTDL and sdtrl 3k resistor load

Listed in 1401 SMS card usage

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

Saturated Drift Transistor Resistor Logic (SDTRL) is a form of resistor-transistor logic using faster drift-field transistors.

Part number: 370371

PCB number: 492345

Used in: IBM 1401, IBM 1410

IBM SMS card type DHD 370371

References: 1410_SMS_VOL_1.pdf, p95
Coslet data
2_2 SMS Cards, p98
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.