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

Function of the card:
2-5 way -a-0 dlb w or wo/load h.s.
2-5 Way (-A-O) DLB Load or No Load H. S.

Part number: 372525

Customer Eng reference number: 734375

PCB number: 484961

Used in: IBM 2821 Control Unit

Symbol:-A, R, -O

-A: Negative AND. In-phase output is negative only when all inputs are negative. Out-of-phase output is positive for the above condition.

R: Load. Provides proper terminating impedance or optimum coupling of one circuit to another at the correct operating voltage level.

-O: Negative OR. In-phase output is negative if one or more Input signals are negative. Outof-phase output is positive for the above condition.
IBM SMS card type CEZ 372525 IBM SMS card type CEZ 372525

References: IBM 2821 CCD, p39
National Museum of Computing.
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.