A BA11-V is a small Qbus mounting box, the same size as a TU58. IIRC it contains 4 dual-height Q-bus slots (probably Q18 only) and a PSU. The auffix 'A' may mean it's set for 115V mains. I have no idea what the prefix 'O' means I beleive some model of TU58 didn't have an internal PSU, rather it took power from the PSU of a BA11-V that it was bolted to. May be worth checking. What (if anything) is in the Qbus slots of the BA11-V? [As an aside, the BA11-V was not uncommon in the UK as the housing for what was known as a 'York Box'. This was a unit to connect standard-ish hosts (PERQs and VAXen mostly I think) to the then-current X25 network. The BA11-V contains an SBC21 ('Falcon') CPU card, a RAM card (32Kw, I forget the model number, but it's the standard one), a DPV11 (sync serial port to connect to the X25 line) and a DR11 (parallel interface). The host was conenected either to the DRV11 (using, perhaps a DR11 in a VAX) or to one of the RS232 ports (async) on the SBC21)] -tony