cbmbasic (Commodore BASIC V2 as a scripting language)

Commodore BASIC (cbmbasic) is a 100% compatible version of Commodore's
version of Microsoft 6502 BASIC as found on the Commodore 64. You
can use it in interactive mode or pass a BASIC file as a command line
parameter.

This does not emulate 6502 code; all code is completely native. On a
1GHz CPU you get about 1000x speed compared to a 1MHz 6502.
