Port of BBC Micro OS (MOS) and BBC BASIC to Commodore 64. Currently modifying the MOS ROM source code to work with the C64 hardware.
Build with the ACME Assembler. You'll need a version of ACME built from source code to get the feature that enables calling a macro passed as an argument to another macro, which is required to build the BASIC tables.
Original BBC BASIC annotated source code.
Original MOS 1.20 annotated source code.