The Commodore CBM-II series is a short-lived range of 8-bit personal computers from Commodore Business Machines (CBM), released in 1982 and intended as a follow-on to the Commodore PET series. Technical description 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 (hi-profile) with detached keyboard, and also 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. The P-series uses the VIC-II 40-column color video chip like the Commodore 64 (C64). It also includes two standard Atari-style joystick ports. The 6509 CPU runs at 1 MHz in the P-series due to the use of the VIC-II chip. Both B and P-series machines have a 6581 SID chip, although the B-series' 2 MHz clock speed makes it impossible to read any of the SID's registers. The B-series uses a 6545 CRTC video chip to give an 80-column "green screen" monochrome output more suitable for word processing and other business use than the VIC-II's 40-column display. Most models have the Motorola 68B45 installed which is a pin-compatible variant rather than the MOS 6545A1 2 MHz part. On the B-series the 6509 CPU runs at 2 MHz. The joystick ports are not present on the B-series, but the connector is still on the motherboard. CBM-IIs are the only Commodore 8-bit machines with an RS-232 port instead of the standard user port. The I/O registers for the user port are still present (as they're an internal function of the 6522 chips) but there is no connector for it on the motherboard. A cartridge slot is also included on the machines; however, no known cartridge software was developed. The B-series retained the IEEE-488 interface from the PET instead of the IEC serial interface on the VIC-20 and C64. The small amount of software Commodore developed for the B-series was distributed on 500k 8050 format disks rather than the 170k 4040/1541 format. Features common to both the P and B-series included an MOS Technology 6509 CPU, an enhanced version of