Shortly after the release of Atari BASIC, the owner of Shepardson decided to dissolve the company. The Atari staff formed their own company, Optimized Systems Software (OSS), and purchased the licenses to the Atari products. Basic A+ was one of OSS's first products, consisting largely of the bug-fixed versions of Atari BASIC along with a few expansions. Among the notable additions were PRINT USING (for formatted output), trace and debug enhancements, and direct DOS commands.
Too large to fit on a 8k ROM, the product was sold on disk only. Because BASIC A+ had to be purchased, programs developed using its extended features could not be shared with people who did not own the interpreter. A+ was never particularly popular, and soon superseded by the greatly improved Basic XL.