Consists of SBI backplane plus power supply. MicroVAX 3400 provides four option panel spaces for additional memory, (MS780-C/D, MS780-E/F or MS780-H/J), DW780, DR780, CI780, MBAs (MASSBUS adapters), and MA780 multiport interfaces. The CPU expansion cabinet also includes space for one H7112-A/B memory battery backup option. There are two locations for MicroVAX 3400 for mounting the power supplies included with the above options. OPS slots one and two share one supply location while OPS slots three and four share the other. There is a limit of two H9652-H cabinets per each MicroVAX 3400 or 11/780 system. UNIBUS expansion cabinets measure 106 centimeters high by 53 centimeters wide by 80 centimeters deep (41.8 inches high by 21.0 inches wide by 31.5 inches deep). The module(s) of a UNIBUS controller/interface mount in the DD11-CK,-DK UNIBUS backplanes which are mounted in a BAll-K box. The I/O connector panel inserts included with a UNIBUS option mount in the rear I/O connector panel mounting frames in the space(s) filled with blank insert panels. H9642-FA/FB UNIBUS expansion cabinet with space for one BAll-K expander box and one 26.6 centimeter (10.5-inch) disk, front loading. The cabinet for MicroVAX 3400 is partitioned into two sections. The top 26.6 centimeters (10.5 inches) of mounting space support an RL02, RA80, or RA81 disk. The remaining space supports a BAll-K expander box (ordered separately). The cabinet provides connection panel space to mount three groups of four panel units each and one additional panel unit. H9642-FC/FD This cabinet is fully shielded and contains a controller, an I/O connector panel, and space for a BA11-K or BA11-A expander box. The I/O connector panel has space to mount seven groups of four panel units each and one additional panel unit.