Attended an Acorn BBC User Group (ABUG) gathering at the Centre for Computing History in Cambridge at the weekend. Amongst the Acorn items that we managed to archive were four Acorn Communicators, and all had different ROM sets.
The first is a very early example donated by Acorn co-founder Chris Curry. The serial ends in 004 and after adding to MAME turns out to be an evaluation prototype from 1985 (according to the not yet present Help option).
Another later prototype from 1986 runs the same MOS but a different selection of apps.
A later production model turned out to be the elusive Italian version.
There was also the Briefcase Communicator http://www.computinghistory.org.uk/det/1327/Acorn-Briefcase-Communicator/
on display, which we painstakingly disassembled. This ran the same MOS v1.00 set already in MAME, but also hiding in the briefcase was an expansion board containing another ROM and 8 'ASTRON Card Slots'. With the ROM present the machine reports MOS v1.70.