The Commodore CBM B500, was a similar computer to the P500, but for the business market. The VIC-II chip was replaced by a MOS 6545 CRT Controller, capable of 80 columns text. The SID Sound chip was not removed, but the two joystick ports were. Interestingly, the connectors do exist on the motherboard but the ports in the backside of the case have been removed in this model.

The B500 ran Commodore BASIC 4.0, and came in two versions. One version had 128K RAM, with 64kByte for BASIC and 64kByte for storage, and a version with 256kByte of RAM. This version used three banks of 64kByte of RAM for variable storage.

For storage these computers could use external cassette tapes or disk drives.

The Commodore 500 series was introduced in 1982. They are very similar to the CBM 600 series computers, which were launched at about the same time. Memory ranged from 64KByte to 256KByte. There were three models:

• Model 505 - 64KByte RAM (No documentation found about this machine)
• Model P500 - 128KByte RAM for the professional market
• Model B500 (CBM 510) - 128KByte RAM for the Business Market
• Model B500 (CBM 520) - 256KByte RAM for the Business Market

The machines have 24KByte ROM, a IEEE-488 Bus, a dual 8-bit user port, a RS232C communications port. It also has a joystick port, accessible on the motherboard, but there is no hole in the case for it.

The CBM 500 series uses a lot of the same chips that the Commodore 64 uses are used in the 500 series:

• VIC-II video chip - 320x200, 16 colors, 40 column text
• SID 6581 Sound chip - 3 channel sound

The 500 series uses the MOS Technology 6509 CPU which is capable of addressing up to 1MByte of RAM where the C64 uses the MOS 6502 which can only address 64KByte. In the end, the 500 series did not get produced for the American market due to regulatory problems and the fact that the C64 was much cheaper to manufacture.

Features:

• Extended Basic v4.0
• 40x25 video mode in 16 colors (VIC-II)
• 64/128/256 KByte memory
• MOS 6509 CPU, Clocked at 1MHz
• Built in machine language monitor
• 2 joystick ports, user port & cartridge port
• IEEE488 parallel connector, RS232C port

The CBM-II has two incarnations, the P series (P = personal, or, home use) and the B series (B = business use). The B series was available with a built-in monochrome monitor with detached keyboard (hi-profile) but also available as a single unit with built-in keyboard but no monitor (lo-profile). These machines are often referred to as the "Porsche PETs" due to incorrect rumors that the case was designed by Porsche. Though Commodore did initially consult Porsche for a case design, it proved too expensive to produce, so Commodore enlisted designer Ira Velinski to create one based on the original PET prototype