 The entire AmigaDOS module was originally written in BCPL (an ancestor of the C programming language), the same language used to write TRIPOS.AmigaDOS would later be rewritten in C from AmigaOS 2.x onwards, retaining backwards compatibility with 1.x up until AmigaOS 4 (completely rewritten in C) when AmigaDOS abandoned its BCPL legacy.TRIPOS provided features such as pre-emptive multi-tasking (using strict-priority scheduling), a hierarchical file system and multiple command line interpreters.