An interesting British, cross platform, Multi-user OS written in COBOL. For mainframes PDP-11, VAX, 8080, 6800 and Z80 machines.
According Wikipedia Business Operating System
https://thedarts.eu/comphist/comphist.html
Also in Practical Computing, July 1987 (page 92) next to other multi-user OSes, floppy disks can be used in either machine (but how to put an 8" floppy into a home computer disk drive?)
There are several other operaing systems called BOS (next to BOSS)
BOS (1) 1969 For medium-scale batch processing. Capable of simultaneously executing one batch process and up to two sub processes. Fujitsu FACOM 230 and 235 Fujitsu, Japan -
BOS (2) 1974< Basic OS for Interdata (later Perkin-Elmer) minicomputers. Interdata computers Interdata, USA -
BOS (3) 1970s Batch operating system for Honeywell System 700. Honeywell System 700 Honeywell, USA -
BOS (4) 1970s Operating system for Billings computers. Billings computers USA -
BOS (5) 2000s Bubach Operating System. No-kernel small x86 operating system written in Assembly. - Christoffer Bubach
BOS II 1971 BOS with Multiprocessing of up to 4 jobs. Fujitsu FACOM 230 and 235 Fujitsu, Japan -
BOS/360 1965 Basic Operating System. Early interim version of DOS/360, briefly available at a few Alpha & Beta System/360 sites IBM System/360 IBM, USA
BOS/5 1980s Business Operating Software. Business oriented OS for Z80, PDP-11, 8086, and 68000. Z80, PDP-11, i8086, and 68000 BOS National, USA -
BOS/D 1976 Business Oriented System. Floppy-disk oriented operating system for OKITAC office computers. Oki OKITAC System 9 Oki, Japan
BOS/F 1976 Business Oriented System. Hard-disk oriented operating system for OKITAC office computers. Oki OKITAC System 9 Oki, Japan
BOS/NET 1980s Multitasking, multiprocessing version of BOS/5. - USA -
BOS/VS 1974 BOS with Virtual memory control. Fujitsu FACOM 230 and 235 Fujitsu, Japan