Programming DOS65 is made easy with a range of languages typical for the 80ties.

AS + ED Macro assembler and Text Editor

Basic, started life as Microsoft KB9 for the KIM-1. Relocated for DOS65, file support added (six open files, random access).

Pascal compiler, conforms to Pascal User Manual and Report. Written in assembler. Full source (65c02 version).

Comal, alternative interpreter language

Small C Compiler, subset Kernigan And Richie

AVR Forth