BBC BASIC development

27-Feb-2009: Static variables implemented, variable reading and assignment mostly working, indirection working. Added ^ (AddrOf) function, calls to MOS functions working with returned registers returned to evaluator the correct way around. More work on getting interface to real Unix working. Bit of a slog getting SIGINT and SIGQUIT background handler working properly while allowing them to operate while waiting for raw-ish input.
01-Sep-2008: Full 7-level recursive expression evaluator written, full set of integer arithmetic routines, decimal number printing, completed all I/O commands.
12-Feb-2008: Forgot to demo I/O commands when could see results. All work, but with test code removed from PRINT, can't see results of functions.
12-Feb-2008: PRINT works, including all print formatting. Number output currently returns a dummy string.
05-Feb-2008: Input doesn't echo, DEL in line input backspaces, ESC returns escape state and returns to generate error quitting restores tty state.
01-Feb-2008: Execution dispatch works. PRINT currently justs prints the evaluation result: type, value: string, string length, string start or integer, b16-b31, b0-b15 or real exponent, mantissa b16-b31, b0-b15. tty settings not set, so input echoes, and BS causes a quit.
31-Jan-2008: Reads input line, but dumps core Reading words from non-word aligned addresses
30-Jan-2008: Successfully starts up