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

Function of the card:
2-5 way-no load.
SDTDL 2-5 way -a-o w and wo/load

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

Part number: 372209

Customer Eng reference number: 734374

PCB number: 484961 , hole pattern: 493457

Used in: IBM 1443 Printer, IBM 2821 Control Unit

Symbol:-A, -O

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

-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.

References: IBM 2821 CCD, p27
IBM 1443 ALD, p83
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.