1、INCITS TR-21-1999Information Technology Enhanced BIOS Services for Disk DrivesCopyright American National Standards Institute Provided by IHS under license with ANSINot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Copyright American National Standards Institute Prov
2、ided by IHS under license with ANSINot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NCITS TR-21-1999NCITS Technical ReportInformation Technology Enhanced BIOS Services for Disk DrivesSecretariatInformation Technology Industry CouncilAbstractThis technical report des
3、cribes new services provided by BIOS firmware to support ATA hard disks up to16 mega-tera-bytes (16x1018). Older BIOS services have a compatibility limit of 528 MB and a theoreticallimit of 8.4 GB.Copyright American National Standards Institute Provided by IHS under license with ANSINot for ResaleNo
4、 reproduction or networking permitted without license from IHS-,-,-This Technical Report is one in a series produced by the National Committee forInformation Technology Standards (NCITS). The secretariat for NCITS is held bythe Information Technology Industry Council (ITI), 1250 Eye Street, NW, Suit
5、e 200,Washington, DC 20005.As a by-product of the standards development process and the resources ofknowledge devoted to it, NCITS from time to time produces Technical Reports.Such Technical Reports are not standards, nor are they intended to be used assuch.NCITS Technical Reports are produced in so
6、me cases to disseminate thetechnical and logical concepts reflected in standards already published or underdevelopment. In other cases, they derive from studies in areas where it is foundpremature to develop a standard due to a still changing technology, orinappropriate to develop a rigorous standar
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11、d toavoid infringement in the use of this Technical Report.NCITSTechnicalReportSeriesPublished byAmerican National Standards Institute11 West 42nd Street, New York, New York 10036Copyright 1999 by Information Technology Industry Council (ITI)All rights reservedNo part of this publication may be repr
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13、 permitted without license from IHS-,-,-T13/1226DT Revision 7Page 1Contents PageForeword 41 Scope 12 Definitions and abbreviations . 22.1 Enhanced BIOS 22.2 Enhanced ATA Device . 22.3 Enhanced ATA Channel . 22.4 Conventional vs enhanced . 22.5 Logical Address 22.6 Physical Address 23 Device Paramete
14、r Tables (DPT) 33.1 Device Parameter Table (DPT) Extensions 33.2 The 528-megabyte barrier 33.3 Device capacities greater than 7.9 GB 53.4 Device Parameter Table (DPT) definitions 53.5 Device Parameter Table (DPT) Extension 74 BIOS extensions 104.1 Extended Int 13h calling conventions 104.2 Int 13h e
15、xtensions 124.3 Int 15h removable media eject 175 Compatibility issues . 195.1 Int 41h/46h . 195.2 Disk drive mapping . 195.3 Geometric translations 19Copyright American National Standards Institute Provided by IHS under license with ANSINot for ResaleNo reproduction or networking permitted without
16、license from IHS-,-,-T13/1226DT Revision 7Page 2Tables PageT ABLE 1 D ISK DRIVE MIN / MAX 3T ABLE 2 B IT S HIFT T RANSLATION . 4T ABLE 3 LBA ASSIST TRANSLATION 4T ABLE 4 S TANDARD DEVICE PARAMETER TABLE 6T ABLE 5 T RANSLATED DEVICE PARAMETER TABLE . 6T ABLE 6 D EVICE PARAMETER TABLE EXTENSION . 7T A
17、BLE 7 T RANSLATION TYPE . 9T ABLE 8 D EVICE ADDRESS PACKET . 11T ABLE 9 E XTENSION RESULT BUFFER 12T ABLE 10 R ESULT BUFFER 16T ABLE 11 H ARDWARE CONFIGURATION SUB - FUNCTIONS 17Copyright American National Standards Institute Provided by IHS under license with ANSINot for ResaleNo reproduction or ne
18、tworking permitted without license from IHS-,-,-T13/1226DT Revision 7Page 3AnnexPageA Bibliography 21Copyright American National Standards Institute Provided by IHS under license with ANSINot for ResaleNo reproduction or networking permitted without license from IHS-,-,-T13/1226DT Revision 7Page 4Fo
19、reword(This foreword is not part of American National Standard X3.*-199x.)This technical report describes new services provided by BIOS firmware to support ATA hard disks up to 16mega-tera-bytes (16x10 18 ). Older BIOS services have a compatibility limit of 528 MB and a theoretical limit of8.4 GB.Th
20、is technical report was developed by the ATA/ATAPI ad hoc working group of T13 during 1996-1997. Theapproval process started in 199x. This technical report includes an annex that is informative and is notconsidered part of the technical report.Requests for interpretation, suggestions for improvement
21、 and addenda, or defect reports are welcome. Theyshould be sent to the NCITS Secretariat, Information Technology Industry Council, 1250 Eye Street, NW, Suite200, Washington, DC 20005-3922.This technical report was processed and approved for submittal to ANSI by Accredited Standards Committee onInfor
22、mation Processing Systems, NCITS. Committee approval of the technical does not necessarily imply that allcommittee members voted for approval. At the time it approved this technical, the NCITS Committee had thefollowing members:James D. Converse, ChairmanDonald C. Loughry, Vice-ChairmanJoanne M. Fla
23、nagan, SecretaryOrganization Represented . Name of RepresentativeAmerican Nuclear Society Geraldine C. MainSally Hartzell (Alt.)AMP, Inc Edward KellyCharles Brill (Alt.)Apple Computer . Karen HigginbottomAssociation of the Institute for Certification of Professionals (AICCP) . Kennath ZemrowskiAT Th
24、e Int 13h interface allows more than two drives to be attached to a system but has no consistent methodfor storing the additional parameters; CHS-independent methods for accessing the drives have now been defined. These are drive-geometryindependent and require a different method of address represen
25、tation and operation; New methods of data transfer continue to be added to ATA devices. Capabilities such as, DMA modes,multi-sector data transfers and Fast PIO are not reported to the operating system; Systems require more than two disk drives, and with this requirement comes the requirement to ass
26、ign theorder in which the drives are to be accessed.Copyright American National Standards Institute Provided by IHS under license with ANSINot for ResaleNo reproduction or networking permitted without license from IHS-,-,-T13/1226DT Revision 7Page 22 Definitions and abbreviations2.1 Enhanced BIOSAll
27、 Enhanced BIOSs shall adhere to this technical report. Enhanced BIOSs should support at least one of thefollowing: PIO Mode 3 or greater; DMA Mode 1 or greater.2.2 Enhanced ATA DeviceAn Enhanced ATA Device is a hard disk or other device which interfaces to the system via Integrated DriveElectronics
28、(IDE). These devices must conform to ATA-2(X3.279-1996)/ATAPI(SFF-8020 rev 2.6) or later andshall support: PIO Mode 3 or greater and; DMA Mode 1 or greater.2.3 Enhanced ATA ChannelAn Enhanced ATA Channel (or Chip or interface card) provides a communications port with an Enhanced ATADevice. These cha
29、nnels must be at least ATA-2(X3.279-1996)/ATAPI(SFF-8020 rev 2.6) compliant and have oneof the following capabilities: PIO Mode 3 or greater; DMA Mode 1 or greater.2.4 Conventional vs enhancedWhen a word, term, or phrase is modified by the word “conventional” it refers to the legacy style, or method
30、 ofoperation which is limited to addressing ATA devices which have a 528 MB capacity or below. When a word,term, or phrase is modified by the word “enhanced” it means there is a “conventional” and an “enhanced” methodof operation, the “enhanced” method is defined by this technical report.2.5 Logical
31、 AddressA logical address is used to access a device by an application, such as DOS, using the Int 13 interface. Int 13Fn 8 returns the logical geometry of the device.2.6 Physical AddressA physical address is used to access the drive using the ATA command block registers. Words 1, 3, and 6 of theIDE
32、NTIFY DEVICE data define the physical geometry of a device.Copyright American National Standards Institute Provided by IHS under license with ANSINot for ResaleNo reproduction or networking permitted without license from IHS-,-,-T13/1226DT Revision 7Page 33 Device Parameter Tables (DPT)This clause p
33、rovides a description of the parameter tables that the BIOS makes available to OS and applicationsoftware. Register calling conventions limit the conventional Int 13h interface, resulting in the limitation of OSand application software as well. The Int 13h interface operates directly from the DPT an
34、d therefore limits thesize of the cylinder field in this table.This technical report defines a compatible version of the DPT, that has been implemented by some operatingsystem (OS) developers, that allows the BIOS to change the way the geometry is represented and then totranslate the changed (“logic
35、al“) geometry back to actual (“physical“) geometry when a disk access is performed.This Enhanced FDPT is identified by a signature byte (Axh) that indicates to the system that some form oftranslation is taking place.The DPT is directly accessible only for Int 13h device numbers 80h and 81h. Int 41h
36、and Int 46h providepointers directly to the DPT for drive 80h and 81h respectively. These pointers are maintained for backwardcompatibility with older DOS applications only. Geometry information for drive numbers 82h and above isavailable only through Int 13h function (Fn) 8h and Fn 48h.3.1 Device P
37、arameter Table (DPT) ExtensionsIt has become necessary for the BIOS to store information representing the type of translation currently inoperation, as well as any information relating to the current operation of the drive. One purpose of this technicalreport is to define a standard format for this
38、extension area and to document its fields and functions so that otherOperating System/Application software may easily use this information. This new information, called the “DeviceParameter Table Extension“ is 16 bytes long and is accessed via the extended Int 13h functions described in thistechnica
39、l report. See Table 4 , Table 5 , and Table 6 for a layout of the Device Parameter Table with itsExtension.3.2 The 528-megabyte barrierBIOSs provide Int 13h services for accessing ATA drives from DOS. For conventional Int 13h the Cylinder-Head-Sector (CHS) values supplied to the Int 13h interface we
40、re passed to the drive without modification. This methodof access allows “ill-behaved” applications to successfully access the drive, bypassing the BIOSs Int 13hinterface. ATA drives support more than 1024 cylinders but the Int 13h interface is limited to 1024, this preventsthe BIOS from accessing t
41、he full media by passing CHS values directly to the drive. Table 1 illustrates thelimitations caused by the differences between the Int 13h and ATA maximum geometries.Table 1 Disk drive min/maxBIOS ATA LimitMax sectors/track 63 255 63Max heads 256 16 16Max cylinders 1024 65536 1024Capacity 8.4 GB 13
42、6.9 GB 528 MBThis table illustrates how the conventional Int 13h interface with an 8.4 GB limit is restricted to 528 MB (63 * 16 *1024 * 512). One solution to this problem is to address the drive using the Int 13h Extensions described in thistechnical report. Another solution is to create a false ge
43、ometry that “fits” within Int 13h limitations, and also usesthe full capacity of the drive. This capability is called geometric or drive translation. The translated geometry isapplied in a manner that causes all sectors to maintain the same physical location on the media as when thedrive is used in
44、an untranslated environment. The Int 13h interface only has 10 bits for the cylinder, therefore Int13h Fn 08h always returns the altered geometry information. This allows all DOS applications to functionnormally. Windows 3.11 and below functions normally when 32-bit disk access mode is disabled. A W
45、indows driver which supports the geometry reported by Int 13h Fn 08h is required for 32-bit protected disk access mode.Due to the lack of a recognized standard, several independent drive translation methods have been implementedwhich do not conform to this technical report, thus causing a drive inte
46、rchange problem. The root of the problemis in the boot code and Partition Table stored at CHS=0,0,1. The boot sequence assumes that the geometrystored in the Partition Table matches the geometry returned by Int 13h Fn 08h. When a drive is moved from theCopyright American National Standards Institute
47、 Provided by IHS under license with ANSINot for ResaleNo reproduction or networking permitted without license from IHS-,-,-T13/1226DT Revision 7Page 4original system where the partitions were defined, to a new system with a different translation method, the bootsequence will use Int 13h with boundar
48、ies defined by the Partition Table in the boot sector. Boot failures are thencaused because the geometry in the partition table does not match the BIOS geometry.A simple bit-shift mapping scheme may create altered drive geometries. This method has the advantage ofworking with all ATA drives, including those drives which do not support LBA. A second advantage is thatoperation is fast and the code is small. The disadvantage of this method is that it lacks the flexibility to translateall geometries reported by a drive with a capacity less than 8.4 GB. However, drives which are ATA-2 (X3
