Mystery PERT 26/31 boards

[anachrocomputer]

I found two mystery PCBs in the loft, one with a pair of LM399 voltage references on it. The same board also has a pair of 12-bit CMOS DAC modules, dated 1983. It looks unused. The other board has a pair of 8085 chips on it, plus SRAM and a UART (but no EPROM). The boards have gold fingers on them for use with an edge connector. The two sets of fingers are different sizes and different pitches (but they're much smaller than Multibus). Both boards have "PERT 26/31" on them, which I think is a SCADA communications standard or protocol.

Does anyone know anything about them? Or about PERT 26/31?

Photos of the boards are on Flickr, here: https://www.flickr.com/photos/anachrocomputer/albums/72157668277965635

[rrinker]

 Ah those pre-search engine companies who thought they were being cute by naming the company BASIC. All that does is make searching for any information more difficult nowadays.

[bitslice]

Pert 1900 was an ICL machine, but that pre-dated this board by a decade

ICL were fond of naming things with a slash in the middle though