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

Function of the card:
SDTDL memory .525 usec delay line

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

Part number: 370247

Customer Eng reference number: 734351

Used in: IBM 2821 Control Unit, IBM 1311 Disk


DLY: Delay. Delays a pulse for a certain specified constant time.

References: IBM 1311 ILD, p119
IBM 2821 CCD, p47
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.