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

Function of the card:
Diff Base – Gate Matrix Switch Select #2

Part number: 370331

Used in: IBM 7090

IBM SMS card type DBW 370331 IBM SMS card type DBW 370331

Image courtesy of Computer History Museum

References: Drawing courtesy of Living Computers: Museum + Lab
This page created by Ken Shirriff on Wed Sep 15 18:15:09 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.