BA11 mounting boxes

The BA11 is the name for a series of hex system unit backplane mounting boxes for the H960 series of 19"-wide racks produced by DEC. Although they were intended to be rack-mounted, many were available in table-top configuration as well.

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 BA11 mounting boxes were designed for these spaces.

They included:

• BA11 - used in the PDP-11/20 (see below)
• BA11-A - a late unit, used for the PDP-11/44
• BA11-D - used for the PDP-11/05
• BA11-F - used in the larger -11's like the PDP-11/45
• BA11-K - used to hold both CPUs as well as devices
• BA11-L - ditto

The -F was a 21" box, and the -L a 5-1/4"; the rest were all 10-1/2".

There were also two boxes in the BA11 series which held quad QBUS backplanes:

• BA11-N
• BA11-S

BA11

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

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

The system units were also mounted transversely, but because the cooling fans were mounted along the side of the box, it 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.