The Commodore B128-80 was to be the successor to the popular Commodore PET system. The "B" stands for "business", as this was Commodore's attempt to enter the market with a serious and powerful computer system which could compete with the other popular computers of the time. This line actually did fairly well in the small business realm, but was eventually scrapped for the PC-clones. There were several models in this business line including B128, B256, B128-80HP, B256-80HP and B500 in the U.S, and the CBM 500, 610, 620, 700, 710, and 720 in Europe. The 610 and 620 correspond to the B128 and B256 respectively, while the CBM 710 and 720 correspond to the B128-80HP, and B256-80HP respectively. All the machines in this line are distinguished by the MOS 6509 processor, Commodore BASIC 4.0, Commodore "SID" sound chip, an RS232-C port, IEEE-488 peripheral compatibility, and 80 column text video capability.

The B128, B256, B500, CBM 500, CBM 610, and CBM 620 constitute the "Low Profile" machines. A single integrated unit featuring a full business keyboard, numeric keypad, and 12 function keys.