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

Function of the card:
SDTDL memory 1.200 usec delay line
SDTDL memory 1.2 usec delay line
SDTDL memory 1.200 usec delay line.

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

Part number: 370249

Customer Eng reference number: 734352

PCB number: 493389 , hole pattern: 492672

Used in: IBM 2821 Control Unit, IBM 1311 Disk, IBM 1410


DLY: Delay. Delays a pulse for a certain specified constant time.
IBM SMS card type DGH 370249 IBM SMS card type DGH 370249

Image courtesy of Henk Stegeman

References: IBM 1311 ILD, p120
IBM 2821 CCD, p48
1410_SMS_VOL_1.pdf, p62
This page created by Ken Shirriff on Wed Sep 15 18:15:10 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.