4 Channel Asynchronous Option

This document provides a comprehensive description of a 4-channel asynchronous option, likely an expansion board, for Digital Equipment Corporation. It includes detailed information across seven pages:

• Page 1 serves as the title page, listing various drawing numbers, part numbers, and descriptions, primarily referring to "4CH. ASYNC. OPTION" and "ETCHED CIRCUIT BOARD." It also states the copyright to Digital Equipment Corporation.
• Page 2 presents a component-side view of the circuit board, indicating the placement of components, with a specific note about one item mounted on the wiring side.
• Page 3 shows etch views of both Side 1 and Side 2 of the circuit board, illustrating the copper traces.
• Page 4 contains a detailed parts list, specifying individual electronic components such as capacitors, diodes, headers, DIP switches, and integrated circuits (e.g., 9636 drivers, 9637 receivers, 8255A-5 programmable interface, receiver PCI), along with their quantities and reference designators. It also includes a revision history.
• Page 5 provides a power and ground table for various ICs, outlining pin assignments and connections for different signals (e.g., BAD, UA, SEL, RESET, REC, TX) and power rails (+12V, +5V, -12V).
• Page 6 features a schematic diagram detailing the interconnections for multiple asynchronous channels (channels 4-7), including function switches for port mapping and synchronization selection.
• Page 7 continues with schematic diagrams, showing more granular connections for channels 4-7, focusing on EIA (Electronic Industries Alliance) signals (e.g., REC, RING, CD, DSR, XMIT, DTR, CARRIER) and utilizing 9637 receivers and 9636 drivers, with notes regarding resistor values for signal slew rate.

Overall, the document covers the design, component breakdown, and electrical schematics for the 4-channel asynchronous option.