W851

This document is a 1967 electrical schematic for the Digital Equipment Corporation PDP-IO BUS CONNECTOR BOARD W851. It is provided for test and maintenance purposes and details the proprietary circuitry of this interface board.

The schematic illustrates a circuit with:

• Two main sections, each featuring a bipolar transistor (Q1, Q2) and associated passive components like resistors (R1-R10) and capacitors (C1-C10) for filtering and coupling.
• A large array of diodes (D1-D46) connected to numerous labeled input/output pins (e.g., AC-AV and BC-BV), specified with various color codes (e.g., Blue, Red, Green, White, Silver, Black), indicating its function as a bus connector.
• Connections for Ground (GND) and -15V power.

The document also includes a comprehensive parts list, detailing specific component types (transistor: DEC3638B or DEC6534D, diodes: D664 or D662, specific resistor and capacitor values) and their corresponding part numbers. Additionally, a transistor and diode conversion chart provides DEC and EIA equivalents for the listed components. The schematic has undergone several revisions, with the latest being 'D'.