BASIC09 is a version of the BASIC programming language designed to run on the Motorola 6809 microprocessor, which was used in home computers of the late 70s and early 80s. The language has extensions that allow it to manipulate hardware directly. Its commands are similar to other BASIC dialects with features such as line labels, subroutines, loops, and conditional statements. BASIC09 can create GUI applications by calling operating system routines to draw windows and perform other user interface tasks without deep system knowledge.