Maxtor 4320 manual Read Commands, Read Sectors, Read Verify Sectors

Page 50

INTERFACECOMMANDS

Read Commands

Read Sector(s)

Reads from 1 to 256 sectors, as specified in the Command Block, beginning at the specified sector. (A sector count of 0 requests 256 sectors.) Immediately after the Command register is written, the drive sets the BSY bit and begins execution of the command. If the drive is not already on the desired track, an implied seek is performed.

Once at the desired track, the drive searches for the data address mark of the requested sector. The data address mark must be recognized within a specified number of bytes, or the Data Address Mark Not Found error will be reported. Assuming the data address mark is found:

1.The data field is read into the sector buffer.

2.Error bits are set (if an error was encountered).

3.The DRQ bit is set.

4.An interrupt is generated.

The DRQ bit is always set, regardless of the presence or absence of an error condition after the sector. Upon command completion, the Command Block registers contain the numbers of the cylinder, head and sector of the last sector read. Back-to-back sector read commands set DRQ and generate an interrupt when the sector buffer is filled at the completion of each sector. The drive is then ready for the data to be read by the host. DRQ is reset and BSY is set immediately when the host empties the sector buffer.

If an error occurs during Read Sector commands, the read terminates at the sector where the error occurred. The host may then read the Command Block to determine the nature of that error, and the sector where it happened. If the error type is a correctable or an non-correctable data error, the flawed data is loaded into the sector buffer.

A Read Long command sets the Long bit in the command code and returns the data and the ECC bytes in the data field of the specified sector. During a Read Long, the drive does not check the ECC bytes to determine if there has been a data error. The Read Long command is limited to single sector requests.

Read Verify Sector(s)

Identical to the Read Sector(s) command, except that:

1.DRQ is never set,

2.No data is transferred back to the host and

3.The long bit is not valid.

7 – 2

Image 50

Contents HA RD Drive Produc T MA Nual DiamondMax Revisions Manual No Before You Begin U T I O NContents Product Specifications Handling and InstallationAT Interface Description Host Software InterfaceGlossary Interface CommandsService and Support Figures Manual Organization IntroductionMaxtor Corporation AbbreviationsKey Words Signal ConventionsConventions NumberingDiamondMax 4320 Key Features Product DescriptionProduct Features Functional / InterfaceDefect Management Zone DMZ On-the-Fly Hardware Error Correction Code ECCLogical Block Addressing Software ECC CorrectionBuffer Segmentation Read-Ahead ModeCache Management Automatic Write Reallocation AWRMajor HDA Components Cylinder Limitation Subsystem ConfigurationJumper Location/Configuration Dual Drive SupportPerformance Specifications Product SpecificationsDrive Configuration Models and CapacitiesPhysical Dimensions Parameter Standard MetricEPA Energy Star Compliance Power Requirements AveragePower Mode Definitions Environmental LimitsReliability Specifications Shock and VibrationCanadian Emissions Statement Safety Regulatory ComplianceRadiated Electromagnetic Field Emissions EMC Compliance Pre-formatted Drive Handling and InstallationHard Drive Handling Precautions Important NoticeUnpacking and Inspection Multi-pack Shipping ContainerRepacking Physical InstallationRecommended Mounting Configuration Before You Begin General Requirements Mounting Drive in System Attaching Interface Power Cables System Setup Hard Drive Preparation System Hangs During Boot Pin Description Summary Interface ConnectorAT Interface Description PINPIN Name Signal Name Signal Description Pin Description TableTiming Parameters Mode PIO TimingDMA Timing Mode MIN MAX Ultra DMA TimingSustained Ultra DMA Data In Burst Device Terminating an Ultra DMA Data In Burst Initiating an Ultra DMA Data Out Burst Device Pausing an Ultra DMA Data Out Burst Device Terminating an Ultra DMA Data Out Burst Host Software Interface Error RegisterFeatures Register Task File RegistersCylinder Number Registers Sector Count RegisterSector Number Register Device/Head RegisterCommand Register Summary Command Name Command Code Parameters UsedTimer Value TIME-OUT Period Device Control Register Control Diagnostic Registers Alternate Status Register Digital Input RegisterInterrupt Handling Reset and Interrupt HandlingReset Handling Interface Commands Set Feature CommandsRead Verify Sectors Read CommandsRead Sectors Read DMA Read MultipleWrite Sectors Write CommandsSet Multiple Mode Write Verify SectorsWrite Multiple Write DMAValue Description Set Feature CommandsSet Features Mode Power Mode Commands Sleep Mode Identify Drive Initialization CommandsWord Content Description 15-8 = PIO data transfer mode = Write Cache enabled Initialize Drive Parameters Error Code Description Seek, Format and Diagnostic CommandsExecute Drive Diagnostic Format TrackA.R.T. Command Set Execute S.M.A.R.TNo Quibble Service Service and SupportService Policy SupportInternet MaxFax ServiceCustomer Service Access Time GlossaryCylinder Zero Gigabyte GB Logical Block Addressing Read Gate Signal THIN-FILM Media