Humanities › History & Culture The First Historical Hobby and Home Computers The invention of Apple I, Apple II, Commodore PET and TRS-80 Share Flipboard Email Print By Ed Uthman - originally posted to Flickr as Apple I Computer, CC BY-SA 2.0, https://commons.wikimedia.org/w/index.php?curid=7180001 History & Culture Inventions Famous Inventions Famous Inventors Patents & Trademarks Invention Timelines Computers & The Internet American History African American History African History Ancient History and Culture Asian History European History Genealogy Latin American History Medieval & Renaissance History Military History The 20th Century Women's History View More By Mary Bellis Inventions Expert Mary Bellis covered inventions and inventors for ThoughtCo for 18 years. She is known for her independent films and documentaries, including one about Alexander Graham Bell. our editorial process Mary Bellis Updated December 24, 2017 "The first Apple was just a culmination of my whole life." Steve Wozniak, co-founder of Apple Computers In 1975, Steve Wozniak was working for Hewlett Packard, the calculator manufacturers, by day and playing computer hobbyist by night, tinkering with the early computer kits like the Altair. "All the little computer kits that were being touted to hobbyists in 1975 were square or rectangular boxes with non-understandable switches on them,” Wozniak said. He realized that the prices of some computer parts like microprocessors and memory chips had dropped so low that he could buy them with maybe a month's salary. Wozniak decided that he and fellow hobbyist Steve Jobs could afford to build their own home computer. The Apple I Computer Wozniak and Jobs released the Apple I computer on April Fools’ Day 1976. The Apple I was the first single circuit board home computer. It came with a video interface, 8k of RAM and a keyboard. The system incorporated some economical components like dynamic RAM and the 6502 processor, which was designed by Rockwell, produced by MOS Technologies and cost only about $25 dollars at the time. The pair showed the prototype Apple I at a meeting of the Homebrew Computer Club, a local computer hobbyist group based in Palo Alto, California. It was mounted on plywood with all the components visible. A local computer dealer, the Byte Shop, ordered 100 units if Wozniak and Jobs would agree to assemble the kits for their customers. About 200 Apple Is were built and sold over a 10-month period for the superstitious price of $666.66. The Apple II Computer Apple Computers was incorporated in 1977 and the Apple II computer model was released that year. When the first West Coast Computer Faire was held in San Francisco, attendees saw the public debut of the Apple II, available for $1,298. The Apple II was also based on the 6502 processor, but it had color graphics--a first for a personal computer. It used an audio cassette drive for storage. Its original configuration came with 4 kb of RAM, but this was increased to 48 kb a year later and the cassette drive was replaced with a floppy disk drive. The Commodore PET The Commodore PET–a personal electronic transactor or, as rumor has it, named after the "pet rock" fad–was designed by Chuck Peddle. It was first presented at the Winter Consumer Electronics Show in January 1977, and later at the West Coast Computer Faire. The Pet Computer also ran on the 6502 chip, but it cost only $795--half the price of the Apple II. It included 4 kb of RAM, monochrome graphics and an audio cassette drive for data storage. Included was a version of BASIC in 14k of ROM. Microsoft developed its first 6502-based BASIC for the PET and sold the source code to Apple for Apple BASIC. The keyboard, cassette drive and small monochrome display all fit within the same self-contained unit. Jobs and Wozniak showed the Apple I prototype to Commodore and Commodore agreed to buy Apple at one point in time, but Steve Jobs ultimately decided not to sell. Commodore bought MOS Technology instead and designed the PET. The Commodore PET was Apple’s chief rival at the time. The TRS-80 Microcomputer Radio Shack introduced its TRS-80 microcomputer, also nicknamed the "Trash-80,” in 1977. It was based on the Zilog Z80 processor, an 8-bit microprocessor whose instruction set is a superset of the Intel 8080. It came with 4 kb of RAM and 4 kb of ROM with BASIC. An optional expansion box enabled memory expansion and audio cassettes were used for data storage, similar to the PET and the first Apples. Over 10,000 TRS-80s were sold during the first month of production. The later TRS-80 Model II came complete with a disk drive for program and data storage. Only Apple and Radio Shack had machines with disk drives at that time. With the introduction of the disk drive, applications for the personal home computer proliferated as the distribution of software became easier.