Altair BASIC

Summary

Bill Gates and Paul Allen’s BASIC interpreter for the Altair 8800 worked so well that MITS asked them to continue developing it. The friends interrupted their studies, founded Micro-Soft (the original spelling) and worked with MITS in Albuquerque. They hired another of Gates’s fellow students, Monte Davidoff, to implement floating-point arithmetic.

The original interpreter was distributed on punched tape and required 4 KiB of memory. Later versions used cassettes and floppy disks. The first ROM version, 6502 BASIC, appeared for the MOS processor of that name in two forms: an 8 KiB version with eight-digit floating-point numbers and a 9 KiB version with nine-digit numbers.

Apart from the first version, all subsequent interpreters were called Microsoft BASIC. It became the standard for home computers in the 1970s and 1980s.