BA11-F Mounting Box

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The BA11-F Mounting Box from DEC was primarily used in PDP-11/40, PDP-11/45 and PDP-11/70 to hold the CPU and its programmer's console. BA11-F's were also occasionally used in 'expansion box' roles, to hold extra devices, in which case it had a blank front panel.

It held hex system unit backplanes, and could contain up to nine standard size (4-slot) system units, although typically the backplane used to hold the CPU was a 9-slot (for the -11/40) or larger.

It was one of the BA11 mounting boxes, and was usually mounted in one of the H960 series of 19"-wide racks produced by DEC. The H960 racks provided 63" of vertical mounting space, divided into units of 10-1/2", which were further subdividable into a pair of 5-1/4" spaces. The 21" tall (nominally - see below) BA11-F was designed for these spaces. Slides allowed it to be slid forward for maintenance, etc.

The system units were mounted vertically, facing sideways (unlike the later BA11-K mounting box, where they faced up); they were always mounted with the A-row connectors at the backtop near the power distribution panel. A row of cooling fans mounted on the top, and in all later models, bottom, passed air over the boards.

The BA11-F came with the H742 Power Supply, which was a separate unit, permanently mounted directly to the H960, next to the BA11-F; a power harness connected to the two. The power supply contained up to five DEC standard modular regulators; the harness ended in a power distribution panel containing standard DEC power distribution connectors.

The BA11-F's dimensions were 21" high, 17-1/8" wide (including the power supply), and 24" deep. It was usually supplied with a vertical extension on the front, which increased the rack space usage to 31-1/2".