The Commodore P500 is s short-lived computer from the CBM-II series. It has 128KByte of RAM, and similar video and sound capabilities to the Commodore 64.

Due to the MOS 6509 processor, this computer was able to address up to 1MByte of RAM via bank switching, the C64 can only address 64 KByte. The bank switching technology was later re-used in the Commodore 128. The P500 design has two joystick ports on the rear, these were still present in the B500, the business version of this computer, but removed in later versions of the CBM-II computers.

Since the C64 was so much easier to produce, and cheaper as well, the US launch of the P500 was cancelled. In Europe where the machine did launch, the computer was discontinued in favor of the Commodore 64.

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