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

Function of the card:
SDTRL-Distributed Line Terminator with Optional Load Resistors
SDTRL-distributed line terminator with optional load resistors

Listed in 1401 SMS card usage

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

Part number: 370389

PCB number: 484145

Used in: IBM 1401, IBM 1311 Disk, IBM 1410

References: IBM 1311 ILD, p137
2_2 SMS Cards, p122
Coslet data
1410_SMS_VOL_1.pdf, p106
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.