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

Function of the card:
CTDL-High Speed One Way NPN All Loads
U to T Converter (4 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: 371587

Used in: IBM 7070, IBM 1401

Cap code: VP (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 JJVP 371587 IBM SMS card type JJVP 371587 IBM SMS card type JJVP 371587 IBM SMS card type JJVP 371587 IBM SMS card type JJVP 371587 IBM SMS card type JJVP 371587

Image courtesy of Christoph Methfessel
Image courtesy of Randall Neff
Image courtesy of Henk Stegeman

References: 2_2 SMS Cards, p34
IBM Standard Modular System, Component Circuits, p160
1_2 SMS Cards, p41
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.