This is a UNIX Terminal Emulator for the BBC Micro, written in the mid 1980s by Clive D. Rodgers for the Oxford University Physics teaching laboratory, where their two HLH Orion minicomputers were accessed from a lab full of BBC Micros with this emulator installed as the default language ROM.
Some of Clive's original files are published (with his kind permission) in the bbc/ directory. The source file in the top directory is my own disassembly and reverse engineering, designed to be built using the ca65 assembler.