BASIC09

BASIC09 is a structured BASIC programming language dialect developed by Microware on behalf of Motorola for the then-new Motorola 6809 CPU and released in February 1980.^[1] It is primarily used with the OS-9 operating system, released in 1979. Microware also released a version for OS-9/68k on the 68000 as Microware BASIC.^[2]

In contrast to typical BASICs of the era, BASIC09 includes a multi-pass compiler that produces compact bytecode known as I-code. I-code replaces a number of data structures found in other BASICs with direct pointers to code and values, speeding performance. Users can further compile code using the PACK command, at which point it can be called directly by OS-9 and operated as native code. In the case of PACKed code, a cut-down version of the BASIC09 runtime system is used, Runb, further improving memory footprint and load time.

The language includes a number of structured programming additions, including local variables, the ability to ignore line numbers in favor of named routines, user-defined structures, and several distinct base data types including 16-bit and 8-bit (byte) integers, in addition to floating point and strings.