BD50 Asynchronous Serial Line Interface

This document comprises engineering drawings and specifications for the Digital Equipment Corporation BD50 Asynchronous Serial Line Interface. The BD50 is a self-contained, two-channel interface designed to be plug-compatible with the I/O Bus systems of PDP-8 (positive or negative bus), PDP-9, and PDP-9/L computers. It expands a machine's communication capabilities to accommodate two devices, supporting 20 mA current loops or two parallel LA30 (DEC WRITER) units, or a combination thereof. It can also interface with EIA-level devices, such as high-speed asynchronous modems that meet EIA SPEC RS232-C requirements, and operates in full duplex.

Each channel of the BD50 utilizes independent variable clocks for transmitting and receiving, allowing for a wide range of baud rates (110 to 2400 BAUD). The interface supports program interrupt and skip facilities, with jumper-selectable IOTs for different PDP families.

The document provides detailed specifications, including mechanical dimensions (19"w, 53/16"h, 14"d), electrical power requirements (115V AC/60Hz or 230V AC/50Hz, H716 power supply), and operational characteristics (two channels, 20 mA current loop or EIA Levels up to 25 feet). It also outlines various BD50 model variations based on voltage and bus type, programming instructions with recommended IOT codes for both PDP-9 and PDP-8 families, and acceptance criteria requiring successful diagnostic tests and complete documentation.

The bulk of the document consists of various engineering drawings, including a drawing directory, customer print set index, module utilization details, schematics for channel transmitter/receiver and I/O bus interfaces, wire lists, and assembly drawings for level converters and wired assemblies.