Tiny Basic

Tiny BASIC is a dialect of the BASIC programming language that can fit into as little as 2 or 3 KB of memory. This small size made it invaluable in the early days of microcomputers (the mid-1970s), when typical memory size was only 4–8 KB. The prevalence of BASIC on the first generation of home computers is an outcome of Tiny BASIC.

Tiny BASIC is an example of a free software project that existed before the free software movement. It started in the newsletter of the People's Computer Company in 1975. Dennis Allison, a member of the Computer Science faculty at Stanford University, wrote a specification for a simple version of the BASIC programming language. He was urged to create the standard by Bob Albrecht of the Homebrew Computer Club. He had seen BASIC on minicomputers and felt it would be the perfect match for new machines like the MITS Altair 8800, which had been released in January 1975. This design did not support text strings and only used integer arithmetic. The goal was for the program to fit in 2 to 3 kilobytes of memory.

The Tiny BASIC contents of the newsletter soon became Dr. Dobb's Journal of Tiny BASIC with a subtitle of "Calisthenics & Orthodontia, Running Light Without Overbyte." Hobbyists began writing BASIC language interpreters for their microprocessor-based home computers and sending the source code to Dr. Dobb's Journal and other magazines to be published. Dick Whipple and John Arnold wrote an interpreter that required only 3K of RAM. By the middle of 1976, Tiny BASIC interpreters were available for the Intel 8080, the Motorola 6800 and MOS Technology 6502 processors. This was a forerunner of the free software community's collaborative development before the internet allowed easy transfer of files, and was an example of a free software project before the free software movement. Computer hobbyists would exchange paper tapes, cassettes or even retype the files from the printed listings.

...
Wikipedia