Western Digital T13/2132-D Byte, Word at offset n, DWord at word offset n, QWord at word offset n

Page 22

T13/2132-D Revision 3

June 23, 2010

3.3.10 Byte, word, DWord, and QWord Relationships

Figure 2 illustrates the relationship between bytes, words, DWords, and QWords.

Byte																Byte
																Byte
													7	6	5	4	3	2	1	0
												MSB								LSB
Word at offset n												Word n
												Word n
								15 14 13 12 11 10			9	8	7	6	5	4	3	2	1	0
							MSB													LSB
									Byte 2n+1							Byte 2n
DWord at word offset n
							DWord n/2
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10											9	8	7	6	5	4	3	2	1	0
MSB																				LSB
	Byte 2n+3				Byte 2n+2				Byte 2n+1							Byte 2n
		Word n+1										Word n
QWord at word offset n
							QWord n/4
63 ...	56 55 ...		48 47 ...		40 39 ...		32 31 ...		24 23 ...			16 15 ...				8	7		...	0
MSB																				LSB
Byte 2n+7		Byte 2n+6		Byte 2n+5		Byte 2n+4		Byte 2n+3		Byte 2n+2			Byte 2n+1					Byte 2n
	Word n+3				Word n+2				Word n+1							Word n
		DWord n/2+1									DWord n/2

Figure 2 — Byte, word, DWord and QWord relationships

Unless stated or defined otherwise, in a field containing a multi-byte value (e.g., a word, DWord, or QWord), the byte containing the LSB is stored at the lowest offset and the byte containing the MSB is stored at the highest offset.

3.3.11 ATA string convention

ATA strings are sequences of bytes containing ASCII graphic characters in the range of 20h-7Eh. ATA strings shall not contain values in the range of 00h-1Fh or 7Fh-FFh.

10	Working Draft Enhanced Disk Drive - 4 (EDD-4)

Image 22

Contents Information technology Enhanced Disk Drive 4 EDD-4 Revision June 23T13/2132-D Revision 3June 23 Points of ContactWorking Draft Enhanced Disk Drive 4 EDD-4 Draft June 23 T13/2132-D RevisionAmerican National Standard T13/2132-D Revision June 23Document Status New Capabilities added to EDD-4Contents Working Draft Enhanced Disk Drive 4 EDD-4 Vii Viii Working Draft Enhanced Disk Drive 4 EDD-4 Tables Output ParametersFigures Foreword IntroductionXii Working Draft Enhanced Disk Drive 4 EDD-4 BSR Incits ScopeAmerican National Standard for Information Technology ATA8-APT ATA8-AST Approved references Normative references GeneralApproved Ansi References Name Other references References under developmentReferences Under Development Name Project Number June 23 T13/2132-D Revision Conventions Symbols and abbreviationsMaster Boot Record MBR The first LBA on a disk Abbreviation MeaningUnordered lists PrecedenceLists Lists overview Ordered listsT13/2132-D Revision June 23 Keywords NumberingNumbering conventions French English This standard Register and CF ContentsInterrupt Services and Functions Bit conventionsDWord at word offset n ByteWord at offset n QWord at word offset nWord ATA string byte swapping Word Byte Character in stringATA firmware revision example Byte ValueOverview Register Description 8GB INT 13h Functions Conventional FunctionsConventional Register Definitions Bit DescriptionConventional Function Definitions Function a Description Extended Function Definitions 8GB INT 13h Functions OverviewData Structure Function DescriptionT13/2132-D Revision June 23 Device Address Packet Offset Removable Media Fixed Disk Access SubsetFixed Disk Access Function Code INT 13h Interface SubsetsEnhanced Disk Drive EDD Support Subset Locking and Ejecting Function CodeEDD Support Function Code CD/DVD Boot Overview ISO 9660 CD Layout Working Draft Enhanced Disk Drive 4 EDD-4System Area Unused Boot Methods Emulation ProcessHard Drive Boot No Emulation BootFloppy Boot Floppy Geometries Type Cylinders Heads SectorsBoot Volume Descriptor Boot Volume Descriptor BVDCD/DVD Format T13/2132-D Revision June 23 Validation Entry Offset Type DescriptionJune 23 T13/2132-D Revision Initial/Default Entry Section Header00h Byte Header ID June 23 T13/2132-D Revision Section Entry Type DescriptionT13/2132-D Revision June 23 Section Entry Extension INT 13h Function Definitions Overview Reset Disk Subsystem FN 00h Get Status of Last Operation FN 01h Read Sectors into Memory FN 02h Write Sectors From Memory FN 03h Verify Sectors FN 04h Get Drive Parameters FN 08h Read Buffer FN 0Eh Write Buffer FN 0Fh Get Disk Type FN 15h Value DescriptionSet Media Type FN 18h Park Heads FN 19h Identify Device Information FN 25h Check Extensions Present FN 41h Interface Support Bit Map DescriptionExtended Read FN 42h Extended Write FN 43h Verify Sectors FN 44h Lock/Unlock Media FN 45h Eject Removable Media FN 46h Get Device Parameters FN 48h Result BufferAscii T13/2132-D Revision June 23 Interface Path Interface Path Definitions part 1 Host Bus Type OffsetDefinition Device Path00h ATA Device 01h 02h..FFh Reserved Byte Word DWord QWord Byte Port number Device parameter table extension Offset 0-1 I/O port base Offset 5 Bios use only Bios use only Offset 6 IRQ numberOffset 7 READ/WRITE Multiple command block count Offset 2-3 control port baseBit 8 Atapi device uses command packet interrupt Offset 10-11 Bios selected hardware specific option flagsBit 7 32-bit transfer mode Offset 9 PIO typeTranslation Type Bits Description Bit 13h 48-bit LBA addressing enabledJune 23 T13/2132-D Revision Bits 9-10 translation type Bit 11 Ultra DMAGet Extended Media Change Status FN 49h Initiate Disk Emulation FN 4Ah Value Emulation Working Draft Enhanced Disk Drive 4 EDD-4 Terminate Disk Emulation FN 4Bh Initiate Disk Emulation & Boot FN 4Ch Return Boot Catalog FN 4Dh CD Command PacketSet Hardware Configuration FN 4Eh Hardware Configuration Sub-FunctionsSend Packet Command FN 50h Formatted Command Packet Offset Type DescriptionFormatted Protocol Specific Data T13/2132-D Revision June 23 Output Parameters Security Protocol Commands FN 51h INT 15h Removable Media Eject GPT support for hybrid MBR boot code Hybrid MBR boot Hybrid MBR boot overviewAnnex a Hybrid MBR boot code Hybrid MBR boot code endeavor procedure EAXHybrid VBR boot code