IBM ESC (374215)  
Written by Accutron on 2017-12-03  

The IBM ESC, P/N 374215 is a Standard Modular System (SMS) card from a currently undetermined mid-1960s IBM system. SMS modules are IBM's second generation modular computer circuit technology, preceded by tube-based finger modules and succeeded by proprietary SLT integrated circuit modules. Unlike SLT modules, SMS cards have a fairly standard PCB construction, and can be easily recognized by their single-sided 16-pin edge connector and an unusual number of topside jumper wires which serve the function of a second board layer. This particular card is a double width type, with 14 diode arrays and 12 TI-manufactured IBM Type 033 alloy junction germanium transistors, manufactured the 13th week of 1967.

IBM ESC (374215) SMS card.

ESC SMS card, underside construction.

This article is part of the [Logic & Memory Circuits] exhibit.

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