Commodore PetEdit

The Commodore PET was one of the first mass-market personal computers, released by Commodore International in 1977. It combined a built-in keyboard, a built-in monochrome monitor, and data storage on a cassette tape into a single, compact unit. Designed around the 8-bit era's philosophy of price-per-performance, the PET aimed to bring computing into schools and small businesses with a turnkey experience. Its all-in-one design and straightforward BASIC interpreter helped many users get up and running quickly, making the PET a popular starting point for tens of thousands of early programmers and computer users. In the broader arc of computing history, the PET helped establish Commodore as a major player and set a precedent for integrated, user-friendly machines that could be deployed with minimal friction in education and light commercial work. Commodore MOS Technology 6502 Commodore BASIC kasette tape cassette tape

History and development

Origins and design goals

Under the leadership of Commodore’s founders, the company pursued a strategy of delivering affordable, easy-to-use machines that could be purchased by individuals, schools, and small offices without extensive configuration. The PET’s design encapsulated this approach: a self-contained unit with a single chassis, a built-in display, and a basic programming environment in ROM. This reduced the need for multiple peripheral purchases and simplified maintenance, a point of appeal for buyers constrained by budgets or unfamiliar with assembling a computer system. The choice of the 6502 CPU and a compact BASIC interpreter reflected the era’s emphasis on cost-effective, accessible computing. The PET was introduced alongside other early Commodore efforts and soon shared a platform philosophy with later machines like the VIC-20 and Commodore 64.

Market introduction and competition

First shipped in 1977, the PET entered a crowded field of early personal computers that included the Apple II and the TRS-80. Its integrated approach stood in contrast to more modular competitors, offering a turnkey experience that appealed to schools and small businesses looking to avoid the complexity of assembling a system from separate parts. The PET’s price point—often cited in the hundreds to low thousands of dollars depending on configuration—was a major selling feature, intended to maximize the return on investment for institutions with tight budgets. The PET’s emphasis on reliability and ease of use helped Commodore win a foothold in markets where many buyers valued straightforward deployment over cutting-edge performance. Apple II TRS-80 cassette tape 5.25-inch disk

Variants and evolution

The early PET models, such as the PET 2001, emphasized a compact, all-in-one package with a built-in monitor and cassette drive. Over time, Commodore expanded the line with variants that offered more RAM and, where feasible, disk-based storage to expand capabilities. The PET family laid groundwork for later 8-bit machines from Commodore, which would continue to push affordable computing into schools and homes. See also the broader lineage of Commodore’s 8-bit machines, including the VIC-20 and Commodore 64 families. PET 2001 CBM DOS

Technical characteristics

  • CPU: 6502 running around 1 MHz, a common speed for early home and education machines.
  • RAM: Base configurations typically included around 4 KB of RAM, with options to expand in some variants.
  • ROM and BASIC: The machine carried a BASIC interpreter in ROM, giving users an immediate programming environment without additional software. The interpreter’s lineage traces to the broader BASIC ecosystem and, on Commodore systems, to Commodore BASIC.
  • Storage: A built-in cassette tape interface provided data storage and loading, complemented by optional disk-based options on later models.
  • Display and input: A built-in monochrome monitor coupled to an integral keyboard made the system a compact, self-contained unit, suitable for classroom demonstrations and small offices.
  • Expandability: Although intentionally streamlined, PETs allowed auxiliary peripherals and, in some configurations, disk storage to broaden capabilities beyond the base system. See also cassette tape for how data was stored on the platform.

Market impact and legacy

The Commodore PET’s all-in-one design and approachable BASIC environment helped popularize personal computing in non-specialist settings. In schools, the PET was often chosen for its reliability and ease of deployment, enabling curricula to incorporate programming and computer literacy with relatively low training costs for teachers. In business contexts, the PET offered a compact, dedicated tool for simple data processing and automation tasks, without requiring a large IT department to maintain.

A key element of the PET’s legacy is how it framed the debate over closed versus open system design. Its integrated chassis and bundled software minimized compatibility headaches for new users but also constrained upgrade paths compared with more open, modular systems. Proponents argued that the PET’s design delivered predictable performance and lower total cost of ownership, while critics claimed that its closed architecture limited long-term growth and hindered third-party expansion. The discussion over these trade-offs helped shape consumer expectations for next-generation machines, including Commodore’s subsequent VIC-20 and later Commodore 64—machines that continued to push price-per-performance advances into the mainstream. Commodore MOS Technology 6502 Commodore BASIC CBM DOS

See also