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

Function of the card:
Cm hi speed 1 way pnp fld replace
CTDL-High Speed One Way PNP No Loads
T to II Converter (no loads)

Listed in 1401 SMS card usage

Complemented Transistor Diode Logic (CTDL) is IBM's term for a form of diode-transistor logic.

Part number: 371579

Field replacement part number: 370982

Used in: IBM 1401, IBM 7070


C: Converter. Used to translate from one voltage level to another, or to change the amplitude of the voltage swing about the same reference level.
IBM SMS card type JF 371579 IBM SMS card type JF 371579

References: 1_2 SMS Cards, p39
2_2 SMS Cards, p20
Coslet data
IBM Standard Modular System, Component Circuits, p157
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.