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

Function of the card:
CTDL-One Way NPN
U to T Converter (2 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: 371275

PCB number: 491443

Used in: IBM 1401, IBM 7070

Cap code: ZT (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 CRZT 371275 IBM SMS card type CRZT 371275 IBM SMS card type CRZT 371275 IBM SMS card type CRZT 371275 IBM SMS card type CRZT 371275 IBM SMS card type CRZT 371275 IBM SMS card type CRZT 371275 IBM SMS card type CRZT 371275 IBM SMS card type CRZT 371275 IBM SMS card type CRZT 371275 IBM SMS card type CRZT 371275 IBM SMS card type CRZT 371275

Image courtesy of Randall Neff

References: IBM Standard Modular System, Component Circuits, p55
2_2 SMS Cards, p2
1_2 SMS Cards, p36
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.