Implement more BBC MOS calls where appropriate.

[soruk42]

BBCSDL has these supported. It is not a stretch to implement these calls for Matrix Brandy also. The framework exists as OSCLI, OSBYTE and OSWORD are supported already. (Taken from the AArch64 BASIC thread on riscosopen.org)

    case 0xFFE0: // OSRDCH
        return (int) osrdch () ;

    case 0xFFE3: // OSASCI
        if (al != 0x0D)
            {
            oswrch (al) ;
            return 0 ;
            }

    case 0xFFE7: // OSNEWL
        crlf () ;
        return 0 ;

    case 0xFFEE: // OSWRCH
        oswrch (al) ;
        return 0 ;

    case 0xFFF1: // OSWORD
        osword (al, (void *) xy) ;
        return 0 ;

    case 0xFFF4: // OSBYTE
        return osbyte (al,xy) ;

    case 0xFFF7: // OSCLI
        oscli ((char *) xy) ;
        return 0 ;

[soruk42]

That's them done.