diff --git a/constants/ATA.inc b/constants/ATA.inc
new file mode 100644
index 0000000..09fa7f2
--- /dev/null
+++ b/constants/ATA.inc
@@ -0,0 +1,116 @@
+; ATA-2 commands ************************
+
+ATA_EXECUTE_DEVICE_DIAGNOSTIC    equ 0x90
+ATA_IDENTIFY_DEVICE              equ 0xec
+ATA_INITIALIZE_DEVICE_PARAMETERS equ 0x91
+ATA_READ_SECTORS                 equ 0x20
+ATA_READ_VERIFY_SECTORS          equ 0x40
+;  equ 0x70-0x7f
+ATA_SEEK                         equ 0x70
+ATA_WRITE_SECTORS                equ 0x30
+
+
+; ****** additional commands ************
+
+ATA_ACKNOWLEDGE_MEDIA_CHANGE   equ 0xdb
+ATA_POST_BOOT                  equ 0xdc
+ATA_PRE_BOOR                   equ 0xdd
+ATA_CHECK_POWER_MODE           equ 0x98
+ATA_CHECK_POWER_MODE2          equ 0xe5
+ATA_DOOR_LOCK                  equ 0xde
+ATA_DOOR_UNLOCK                equ 0xdf
+ATA_DOWNLOAD_MICROCODE         equ 0x92
+ATA_IDLE                       equ 0x97
+ATA_IDLE2                      equ 0xe3
+ATA_IDLE_IMMENDIATE            equ 0x95
+ATA_IDLE_IMMENDIATE2           equ 0xe1
+ATA_MEDIA_EJECT                equ 0xed
+ATA_NOP                        equ 0x00
+ATA_READ_BUFFER                equ 0xe4
+ATA_READ_DMA                   equ 0xc8
+ATA_READ_LONG                  equ 0x22
+ATA_READ_MULTIPLE              equ 0xc4
+;  equ 0x10-0x1f
+ATA_RECALIBRATE                equ 0x10
+ATA_SET_FEATURES               equ 0xef
+ATA_SET_MULTIPLE_MODE          equ 0xc6
+ATA_SLEEP                      equ 0x99
+ATA_SLEEP2                     equ 0xe6
+ATA_STANDBY                    equ 0x96
+ATA_STANDBY2                   equ 0xe2
+ATA_STANDBY_IMMENDIATE         equ 0x94
+ATA_STANDBY2_IMMENDIATE        equ 0xe0
+ATA_WRITE_BUFFER               equ 0xe8
+ATA_WRITE_DMA                  equ 0xca
+ATA_WRITE_LONG                 equ 0x32
+ATA_WRITE_MULTIPLE             equ 0xc5
+ATA_WRITE_SAME                 equ 0xe9
+ATA_WRITE_VERIFY               equ 0x3c
+
+
+; **** device specific commands *************
+
+; TODO remap command
+ATA_FORMAT_TRACK          equ 0x50
+
+
+; command modificators
+; for ATA_READ_SECTORS, ATA_WRITE_SECTORS, ATA_VERIFY_SECTORS,
+;     ATA_READ_DMA, ATA_WRITE_DMA, ATA_READ_LONG, ATA_WRITE_LONG
+ATA_WITHOUT_RETRY         equ 0x01
+
+
+
+
+; ATA registers *****************************
+
+; command registers
+
+ATA_DATA_REG         equ 0
+ATA_ERROR_REG        equ 1
+ATA_FEATURES_REG     equ 1
+ATA_SECTOR_COUNT     equ 2
+ATA_SECTOR_NUMBER    equ 3
+ATA_CYLINDER_LOW     equ 4
+ATA_CYLINDER_HIGH    equ 5
+ATA_DEVICE_HEAD      equ 6
+ATA_STATUS           equ 7
+ATA_COMMAND          equ 7
+
+
+; control registers
+ATA_ALTERNATE_STATUS equ 0x16
+ATA_DEVICE_CONTROL   equ 0x16
+ATA_DRIVE_ADDRESS    equ 0x17
+
+
+; status register bits
+ATA_BUSY           equ 0x80
+ATA_READY          equ 0x40
+ATA_FAULT          equ 0x20
+ATA_SEEK_COMPLETE  equ 0x10
+ATA_DATA_REQUEST   equ 0x08
+ATA_CORRECTED_DATA equ 0x04
+ATA_INDEX          equ 0x02
+ATA_ERROR          equ 0x01
+
+
+; device/head register bits
+ATA_LBA            equ 0x40
+ATA_DEVICE         equ 0x10
+
+
+; device control register bits
+ATA_SOFT_RESET        equ 0x04
+ATA_INTERRUPT_DISABLE equ 0x02
+
+
+; error register bits
+ATA_UNCORRECTABLE          equ 0x40
+ATA_MEDIA_CHANGED          equ 0x20
+ATA_ID_NOT_FOUND           equ 0x10
+ATA_ABORTED                equ 0x08
+ATA_MEDIA_CHANGE_REQUESTED equ 0x04
+ATA_TRACK_0_NOT_FOUND      equ 0x02
+ATA_ADDERSS_MARK_NOT_FOUND equ 0x01
+;
\ No newline at end of file