Serial UNIBUS Repeater?

Mark J. Blair nf6x at
Mon Jun 15 10:57:43 CDT 2015

Has anybody ever made a UNIBUS repeater with a high speed serial link between the bus segments yet? I'm curious because my VAX-11/730 backplane is full, and it would be nice to be able to experiment with additional hardware without needing to pull out one of the existing boards, i.e., adding a TK50 interface without removing the DEUNA, adding a SCSI card to boot from a scsi2sd without pulling the integrated drive controller, etc. There's a blank spot in the TU80 cabinet that looks like it may be tall enough for an expansion chassis, but the thought of adding more big ribbon cables to the belly plate area and then routing them between racks doesn't appeal to me. Running something like a CAT5 cable between the two racks would be a lot easier. Another application would be for placing a small remote UNIBUS backplane on the test bench for easy access, and cabling it to a VAX or PDP-11 elsewhere in the room.

This should be quite possible with modern hardware, but I'm curious about whether something similar has been done before.

Mark J. Blair, NF6X <nf6x at>

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