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

Function of the card:
SDTDL power latch a
Power latch a

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

Part number: 372237

Customer Eng reference number: 734355

PCB number: 484987 , hole pattern: 493499

Used in: IBM 1443 Printer, IBM 1311 Disk

Symbol:+A, -A, DE, -O

+A: Positive AND. in-phase output is positive only when all inputs are positive. Out-of-phase output is negative for the above condition.

-A: Negative AND. In-phase output is negative only when all inputs are negative. Out-of-phase output is positive for the above condition.

DE: Driver Emitter Follower. A driver, operating on the emitter follower principle, used for power amplification, impedance matching, and isolation without inversion. Often used as a logical element.

-O: Negative OR. In-phase output is negative if one or more Input signals are negative. Outof-phase output is positive for the above condition.
IBM SMS card type AXX 372237 IBM SMS card type AXX 372237

Image courtesy of Mag

References: IBM 1443 ALD, p87
IBM 1311 ILD, p96
This page created by Ken Shirriff on Tue Jan 11 17:00:16 2022.

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.