The Commodore B128-80 (at one time, called the C128-80), was to be the successor to the popular Commodore PET system.
The "B" is for "business", of course, as this was Commodore's attempt to enter the market with a serious and powerful computer system which could compete with the other popular units of the time.
There were other similar "B Series" models, some with built-in floppy drives, and even a swivel monitor attached to the top. All of the current Commodore peripherals could be used with the "B Series", this includes cassette data recorders, floppy drives, and printers. From Oldcomputers.net