• 2 x DD11-B 4 slots, 2 reserved for DF11 see the documentation.
• 2 x DD11-PK 9 slots PDP11-34 backplane, see the PDP11-34 documentation (chapter 4).
• MF11-UP 9 slots. that's a core memory with parity backplane. The parity card MUST be installed.
• VT11 subsystem backplane
• Unibus 9 slots.

QBUS