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

Function of the card:
Alloy-Difference Amplifier
Alloy difference amplifier
Alloy Difference Amplifier

Listed in 1401 SMS card usage

Germanium alloy transistors were an early type of transistor, faster than the earlier grown-junction transistors.

Part number: 371671

Used in: IBM 1401, IBM 1410, 7030, IBM 1414 I/O Synchronizer

IBM SMS card type NT 371671 IBM SMS card type NT 371671

Image courtesy of Henk Stegeman

References: 1410_SMS_VOL_2.pdf, p106
2_2 SMS Cards, p49
Coslet data
National Museum of Computing.
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.