M174

This document is an electronic schematic for a "digital 4X9 DATA MIXER", designated as part number M174-0-1, by the Digital Equipment Corporation, copyrighted in 1969.

The schematic primarily illustrates the design using multiple DEC1074H53 Integrated Circuits (IC's), which are depicted as arrays of 4-input NAND gates (labeled E1 through E9). These gates process various input signals (e.g., AAI, ABI, AF2, AD1, etc.) to produce output signals (e.g., AL2, AF1, AL1, AR1, BAI, etc.).

Key features and details include:

• Power Supplies: The circuit operates with +5V and +3V lines, connected to various decoupling capacitors.
• Components: In addition to the DEC1074H53 ICs, the schematic shows resistors and capacitors. Default specifications are provided for these components (e.g., 1/4W, 5% resistors; .01uF, 100V, 20% capacitors).
• Parts List: A comprehensive list enumerates all required components, including flip-chip handles, eyelets, the 9 ICs, various resistors (100Ω, 150Ω), capacitors (.01uF, 39uF), and the etched circuit board. It also lists related engineering documentation such as module ECO history and hole layouts.
• Contextual Notes: A disclaimer states that the schematic is furnished "ONLY FOR TEST AND MAINTENANCE PURPOSES," and that the circuits are "PROPRIETARY IN NATURE." It also notes common IC pin assignments (Pin 7 on each IC = GND).

In summary, it's a proprietary engineering schematic from 1969 detailing the logic and component layout for a 4x9 Data Mixer, primarily utilizing DEC1074H53 NAND gates, intended for test and maintenance.