BASIC09

BASIC09 is a structured BASIC programming language dialect developed by Microware for the then-new Motorola 6809 CPU. Somewhat in the fashion of UCSD Pascal it was implemented via 'compilation' into an intermediate representation. It was paired with the OS-9 Operating system, also from Microware and took advantage of several OS-9 features (e.g., shared memory, module loading and unloading, etc.).

The language processor turned BASIC09 source code into a tokenized, optimized, bytecode, called I-code in the BASIC09 literature. If that bytecode version of the source were saved (called packing), it could also be executed by a much more compact version of the interpreter, called RunB (no editor, no prettyprinter, no extraneous information included for human convenience, no debugger, ...).

BASIC09 had very impressive features for its time (it was first available in 1980), and most especially for its memory requirements. It was also fast, in comparison with nearly all other microcomputer BASICs. Most of the features listed below have significant benefits for those writing more than example programs.

Microware produced a version of BASIC09 for OS-9/68k (for the 68000), calling it Microware BASIC, but did not develop a version for OS-9000 (the portable version of OS-9).