PDP-11/23B Mounting Box

This User's Guide, published by Digital Equipment Corporation in January 1982, provides comprehensive information for the PDP-11/23B Mounting Box (BA11-S), a core component of the PDP-11/23B computer subsystem.

The PDP-11/23B subsystem is introduced as consisting of a BA11-S mounting box, a KDF11-B microprocessor, and MSV11-P memory. The BA11-S itself is a rack-mountable enclosure (19-inch standard) that includes fans, an AC input unit, an H7861 power supply, and a nine-slot H9276 backplane, available with either a control panel or a blank front panel, and supporting 120V or 240V AC.

Key technical details covered include:

• The H9276 backplane's design to support dual- and quad-height LSI-11 modules with 22-bit addressing, detailing its extended LSI-11 bus and CD bus signal lines.
• Module loading considerations, specifically AC loading, DC leakage current, and power consumption, which are critical for system configuration and stability.
• Detailed specifications for the BA11-S mounting box (dimensions, weight, environmental conditions) and the H7861 power supply (current rating, output power, power-up/down characteristics).

The guide provides practical instructions for unpacking, installation, and operation:

• Unpacking: Initial removal from packaging and visual inspection for damage.
• Installation: Thorough preliminary checks including selecting the correct AC voltage, configuring backplane and front panel bezel jumpers, installing power controller cables, and properly inserting/removing modules (emphasizing power-off). It details mounting the logic box cover in an equipment rack and then installing the logic box base into the cover, including restraining cable procedures.
• Power Connections: Different methods for connecting single or multi-box systems to a power source.
• Installation Checks: Utilizing the KDF11-B's on-board diagnostic ROMs for post-installation verification.
• Operation: Explanations of the front panel switches (AUX ON/OFF, HALT, RESTART) and indicators (PWR OK, RUN).