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 principally 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 sub-dividable into a pair of 5-1/4" spaces. The BA11 mounting boxes were designed for these spaces.

They included:

• BA11-A - the terminal letter notwithstanding, a late unit, used for the PDP-11/44
• BA11-B - mentioned briefly in some early documentation; the details of what it was are still unclear
• BA11-C - the first, used in the PDP-11/20
• BA11-D - used for the PDP-11/05 and early PDP-11/40's
• BA11-E - expansion box, used with the early PDP-11s
• BA11-F - used in the larger UNIBUS -11's like the PDP-11/45
• BA11-K - used to hold both CPUs as well as device controllers for UNIBUS -11's
• BA11-L - ditto

The -F was a 21" box, and the -E and -L were 5-1/4"; the rest were all 10-1/2". All of them other than the earliest -C and -E models provided the standard DEC power distribution connectors; the 9-pin version in the -D, and the 6/15 version in the others.

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

• BA11-M
• BA11-N
• BA11-S

These were all 5-1/4" high.