BA11 Mounting Box

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The BA11 mounting box was the first of a series of hex system unit backplane mounting boxes for 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 10-1/2" tall BA11 mounting box was designed for these spaces.

Although they were intended to be rack-mounted, they were available in table-top configuration as well.

BA11's csme in both 'basic box' and 'expansion box' models; the former contained the KA11 processor, and had a programmer's console front panel, and the latter was used to hold extra core main memory systems (each in their own custom system unit) and other devices, and had a blank front panel.

The BA11 came with the H720 Power Supply. The supply was mounted transversely in the box at the rear.

The system units were also mounted transversely, but because the cooling fans were mounted along the side of the box, they could not hold extended-length hex-height cards; only shorter (lower) modules, such as the M920 UNIBUS Jumper, could be placed in the A-row connectors.

The system units faced downward (unlike the later BA11 mounting boxes, where they were facing up); the reason was probably to give easier access to the backplane wiring for debugging. The unit could rotate to give easier access to the boards.

The BA11's dimensions were 10-1/2" high, 19" wide, and 23" deep; the H720 was 8" high, 16-1/2" wide, and 6" deep, and weighed 30 lbs.