G219

This document is an electrical schematic for a Digital Equipment Corporation (DEC) Memory Selector, model G219, copyrighted in 1966.

Key points:

• Purpose: It is furnished for test and maintenance purposes only, and its circuits are proprietary.
• Circuitry: The schematic details a complex digital logic circuit, structured into multiple stages. Each stage appears to involve transistors (MM999 type), transformers (T-2071 type), and various diodes (D-664, D-672 types), resistors, and capacitors.
• Power Supply: The circuit operates on dual power supplies of +10V and -15V, with a common ground.
• Inputs/Outputs: It features multiple input lines (e.g., AV, AU, AS, AD, BV, BU, BS, BD) and output lines (e.g., AK, AJ, BF, BH).
• Component Specifications: Default specifications are provided for components, including 1/4W, 10% resistors. A "Transistor & Diode Conversion Chart" lists DEC part numbers (e.g., MM999, D664, D672) and their EIA equivalents.
• Physical Implementation: The design is intended for use with the etch board of the G209.