* Audio Disc Info      */
typedef struct {
        unsigned char sf_di;          /* call code=10   */
        unsigned char low_track;      /* low track      */
        unsigned char hi_track;       /* high track     */
        unsigned long end_sect;       /* ending sector  */
        } Ainfo_cb;

/* Audio Track Info */
typedef struct {
        unsigned char sf_ti;          /* call code=11       */
        unsigned char track_no;       /* track number       */
        unsigned long st_sect;        /* starting sector    */
        unsigned char control_info;   /* control information*/
        }  Tinfo_cb;

/* Device Status */
typedef struct {
        unsigned char sf_ds;          /* call code=6        */
        unsigned long stat;           /* status bits        */
        } DevStat_cb;

/* Media Changed */
typedef struct {
        unsigned char sf_mc;          /* call code=9        */
        char media_chnged;            /* reply code         */
        } Media_chg_cb;

/* Q-Channel Inquiry */
typedef struct {
        unsigned char sf_qc;          /* call code=12       */
        unsigned char control;        /* control info       */
        char track;                   /* current track #    */
        char point;                   /* point or index     */
               /* running time within the track     */
        char min;                     /* minute             */
        char sec;                     /* second             */
        char frame;                   /* frame              */
        char zero;                    /* unused             */
               /* running time within disc          */
        char dmin;                    /* minute             */
        char dsec;                    /* second             */
        char dframe;                  /* frame              */
        } Q_Chan_cb;

