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

Function of the card:
CTRL-Oscillator, 10 KC Free Running (Crystal)
Ctrl-oscillator, 10 kc free running (crystal)

Listed in 1401 SMS card usage

Complemented Transistor Resistor Logic (CTRL) is IBM's term for a form of resistor-transistor logic.

Part number: 371245

Used in: IBM 1401, IBM 1410

IBM SMS card type JB 371245

Image courtesy of Philipp Müller

References: 2_2 SMS Cards, pp113,114
Coslet data
National Museum of Computing.
1410_SMS_VOL_2.pdf, p68
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.