The Commodore PET ("Personal Electronic Transactor") was a home/personal computer produced from 1977 by Commodore International.
The initial model, PET 2001, was announced at the Winter CES in January 1977 and the first 100 units were shipped later that year in October. However, the PET was back-ordered for months and to ease deliveries, early in 1978 Commodore decided to cancel the 4 KB version.
The PET's 6502 processor controlled the screen, keyboard, cassette machines and any peripherals connected to one of the computer's several expansion ports. The PET 2001 included either 4 KB (2001-4) or 8 KB (2001-8) of 8-bit RAM, and was essentially a single-board computer with discrete logic, driving a small built-in monochrome monitor with 40×25 character graphics.
The 2001 included a built-in Datassette (cassette tape recorder) for data storage. The Datassette was located on the front of the case, which left little room for the keyboard. The data transfer rate to cassette was 1500 baud, with the data being duplicated for safety, giving an effective rate of 750 baud. The computer's main board carried four expansion ports: a second cassette interface, a parallel port, an IEEE-488 port, and a memory expansion port.
Although the PET 2001 was fairly successful, there were frequent complaints about the tiny calculator-like keyboard, often referred to as a "chiclet keyboard" because the keys resembled the gum candy.
Source: Wikipedia, "Commodore PET", available under the CC-BY-SA License.