/* read/write */
#define HDC_DATA    0x1F0
#define HDC_ERROR   0x1F1
#define HDC_SECCOU  0x1F2
#define HDC_SECNUM  0x1F3
#define HDC_CYLLOW  0x1F4
#define HDC_CYLHIGH 0x1F5
#define HDC_SDH     0x1F6

/* read */
#define HDC_STATUS  0x1F7
#define HDC_ALTSTA  0x3F6

/* write */
#define HDC_COMMAND 0x1F7
#define HDC_FIXED   0x3F6

/* commands */
#define HDC_COMMAND_RESTORE 0x10
#define HDC_COMMAND_SEEK    0x70
#define HDC_COMMAND_READ    0x20
#define HDC_COMMAND_WRITE   0x30
#define HDC_COMMAND_FORMAT  0x50
#define HDC_COMMAND_READVER 0x90
#define HDC_COMMAND_DIAG    0x90
#define HDC_COMMAND_SETPAR  0x91
#define HDC_COMMAND_WRSTACK 0xE8
#define HDC_COMMAND_RDSTACK 0xE4
#define HDC_COMMAND_READPAR 0xEC
#define HDC_COMMAND_POWER   0xE0

#define HDC_FIXED_IRQ	    0x02
#define HDC_FIXED_RESET     0x04

#define HDC_STATUS_ERROR    0x01
#define HDC_STATUS_INDEX    0x02
#define HDC_STATUS_ECC	    0x04
#define HDC_STATUS_DRQ	    0x08
#define HDC_STATUS_COMPLETE 0x10
#define HDC_STATUS_WRFAULT  0x20
#define HDC_STATUS_READY    0x40
#define HDC_STATUS_BUSY     0x80