Standard Modular System: Difference between revisions

Revision as of 18:45, 14 April 2015

Revision as of 06:50, 22 April 2015

Line 11:

SMS cards were constructed of individual [[discrete component]]s mounted on single sided paper-epoxy [[printed circuit board]]s. Single width cards were 2.5 inches wide by 4.5 inches tall by 0.056 inches thick, with a 16 pin [[gold]] plated [[edge connector]]. Double width cards were 5.375 inches wide by 4.5 inches tall, with two 16 pin gold plated edge connectors. Contacts were labeled ''A–R'' (skipping ''I'' and ''O'') on the first edge connector, and ''S–Z, 1–8'' on the second.

The cards were plugged into a card-cage back-plane and edge connector contacts connected to [[wire wrap]] pins. All interconnections were made with wire-wrapped connections, except for power bussbus lines. The back-plane wire-wrap connections were mostly made at the factory with automated equipment, but the wire-wrap technology facilitated field-installation of engineering changes by customer engineers.

Some card types could be customized via a "program cap" (a double rail metal jumper bar with 15 connections) that could be cut to change the circuit configuration. Card types with a "program cap" came with it precut for the standard configuration and if a Customer Engineer needed a different configuration in the field he could make additional cuts as needed. This feature was intended to reduce the number of different card types a Customer Engineer had to carry with him to the customer's site.