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

Function of the card:
Alloy – Oscillator 10.0 KC Free Running (Crystal)

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

Part number: 371930

Used in: 7030, IBM 7090


OSC: Oscillator. A free-running non-stable muitivibrator used to provide pulses of a given frequency and amplitude.

References: Drawing courtesy of Living Computers: Museum + Lab
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.