A May 2004 search of Yahoo for "BTOS+CTOS" still yielded about 1,400 hits! When a Unisys developed Microcomputer series/system, circa 1987, that automatically connected into a network, it was thought very innovative. And rather than openning the computer case to add say another hard drive, the series was built as 'slices' that exposed a common bus, thus the various slices could just be hooked together making it simple for the office IT person to 'adjust' a personal system physically.
Fantastic stuff for the era.
One project I did in a B24 (I think) terminal was to make a communication fix, and some keyboard fixes to an American application that provided some user friendly functions when dealing with a PC connected to a mainframe (Unisys A-series). You could actually 'copy' a mainframe file to the PC hard disk, the necessary 'translations', like line endings, provided, then swtich task back to Windows, run Mircrosoft Word, and load the mainframe list, database, information into the fast developing PC world full of user tools.
The particular program was in assembler, but I used the C compiler to build a small keyboard tool, to show me the scan code, the values and states, being returned when certain key combination were received. The French keyboard, like most European keyboards, uses the 2nd Alt key, as an 'Alt Gr' key, which yields a third character on many keys to fill out the character set used to include accented characters..
The communication glich, it would not logon to the A-Series, turned out to be something further down the communication stack was 'eating' the first character, a #. But this character was needed at the mainframe end to begin a sign in decode, and the fix was a 'hack' to insert a space before the trigger character. Luckily the A-Series sign on would always ignore this space, thus it was still a fix that would work after the 'character eater' was also fixed.
A tough bug to track down, and did some small keyboard fixes in between ;-))