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

Function of the card:
Free Running Crystal Oscillator (363.4KC)
Alloy-Oscillator 347.5KC Free Running (Crystal)

Listed in 1401 SMS card usage

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

Part number: 371788

PCB number: 491353

Used in: IBM 1401

Symbol:Osc

IBM SMS card type RK 371788 IBM SMS card type RK 371788 IBM SMS card type RK 371788 IBM SMS card type RK 371788 IBM SMS card type RK 371788 IBM SMS card type RK 371788

Image courtesy of Henk Stegeman

References: IBM Standard Modular System, Component Circuits, pp216,217
2_2 SMS Cards, pp58,59
Coslet data
This page created by Ken Shirriff on Sun Dec 16 16:11:05 2018.

The information on these pages comes from a variety of sources, especially old IBM documents on bitsavers.org, 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.