ch_t
static void set_ch_t(struct ch_t *geo, __u32 cyl, __u8 head)
struct ch_t address;
struct ch_t geo;
struct ch_t beg_ext;
struct ch_t end_ext;
struct ch_t seek_addr;
struct ch_t seek_addr;
struct ch_t beg_ext;
struct ch_t end_ext;