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Friden "Four Counter" EC-132 MDD (Master Design Documentation) Computer Printout, June, 1965

This document is an internal Friden "Master Design Document" (MDD) that describes the entire design of the four-counter version of the EC-132 calculator (Serial Number below 3902). It documents the signals used, logic gate connectivity, and component connectivity and location on the circuit boards for the Four Counter EC-132 (Serial Number <3902).

This document has not been decoded fully in terms of how to read/interpret the content. It is presented here in hopes that it will solicit discussion and perhaps lead to the document being decoded. If you have comments or questions about this document, please contact the curator of the museum.

Section I (glossary) appears to define all of the signal names used in the machine. Section II (logic schematic), appears to define the machine in terms of its logic elements (gates, inverters, flip flops), and how the logic elements are interconnected. Section III (construction file) appears to define the actual component net-list and circuit board component layout.

The document also includes schematics for various subsections of the calculator, as well circuit board layouts, with all components identified by a number that refers back to the Card Map Legend page to specify the component value or part number.

This document is intended to be used with the Friden 132 Logic Schematic for troubleshooting purposes. The Logic Schematic can be used to identify the general logic that could be causing a problem, and the MDD then used to track down the actual components used to implement the logic in question. From there, diagnostic testing can identify any failed or out-of-spec components for replacement.

Any re-distribution of this document, printed or electronic, must include the watermark indicating its source as the Old Calculator Museum. Thank you.

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Friden EC-132 "Four Counter" MDD Computer Printout (June, 1965)

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