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

Function of the card:
H.S. logic inverter
SDTDL logic inv. hs load

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

Part number: 372592

Customer Eng reference number: 734369

Used in: IBM 2821 Control Unit, IBM 1311 Disk

IBM SMS card type ZGP 372592 IBM SMS card type ZGP 372592

References: IBM 2821 CCD, p118
IBM 1311 ILD, p153
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.