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

Function of the card:
SDTDL-Inverter Low Speed w/o Loads
SDTDL inverter low speed w/o load
SDTDL inverter low speed w/0 load
Inverter-no 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.

Part number: 370372

Customer Eng reference number: 729922

PCB number: 484123

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

IBM SMS card type DHC 370372 IBM SMS card type DHC 370372 IBM SMS card type DHC 370372

References: Coslet data
IBM 1311 ILD, p126
1410_SMS_VOL_1.pdf, p96
IBM 1443 ALD, p101
IBM 2821 CCD, p58
2_2 SMS Cards, p97
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.