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

Function of the card:
T to U Converter (2 loads)
CTDL-High Speed One Way PNP Two 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: 371577

Used in: IBM 1401, IBM 7070

Cap code: VN (details, details)

Symbol: C

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 JFVN 371577 IBM SMS card type JFVN 371577 IBM SMS card type JFVN 371577 IBM SMS card type JFVN 371577

Image courtesy of Henk Stegeman

References: IBM Standard Modular System, Component Circuits, p157
2_2 SMS Cards, p22
1_2 SMS Cards, p39
Coslet data
SMS Cap Code Templates & Index
1401 Pocket Reference Manual

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.