Read Commands, Read Sectors, Read Verify Sectors | Maxtor 6800

INTERFACE COMMANDS

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

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Maxtor 6800 manual Read Commands, Read Sectors, Read Verify Sectors

Contents

HA RD Drive Produc T MA Nual DiamondMax U T I O N Before You Begin Contents Handling and Installation Product Specifications Host Software Interface AT Interface Description Service and Support Interface CommandsGlossary Figures Maxtor Corporation IntroductionManual Organization Abbreviations Conventions Signal ConventionsKey Words Numbering Product Description DiamondMax 6800 Key Features Functional / Interface Product Features Logical Block Addressing On-the-Fly Hardware Error Correction Code ECCDefect Management Zone DMZ Software ECC Correction Cache Management Read-Ahead ModeBuffer Segmentation Automatic Write Reallocation AWR Major HDA Components Jumper Location/Configuration Subsystem ConfigurationCylinder Limitation Dual Drive Support Drive Configuration Product SpecificationsPerformance Specifications Models and Capacities Parameter Standard Metric Physical Dimensions Power Mode Definitions Power RequirementsEPA Energy Star Compliance Environmental Limits Shock and Vibration Reliability Specifications Radiated Electromagnetic Field Emissions EMC Compliance Safety Regulatory ComplianceCanadian Emissions Statement Hard Drive Handling Precautions Handling and InstallationPre-formatted Drive Important Notice Multi-pack Shipping Container Unpacking and Inspection Recommended Mounting Configuration Physical InstallationRepacking Tools for Installation Handling PrecautionsSystem Requirements Drive Identification Information Hard Drive Identification General Requirements Installing 5.25-inch Mounting Brackets and Rails Systems Using Cable SelectInstalling in a Device Bay Mounting Drive in System Attaching System Cables Attaching Interface and Power Cables Setting the Bios Cmos System SetupBios Cmos Parameters Hard Drive Preparation System Hangs During Boot AT Interface Description Interface ConnectorPin Description Summary Pin Description Table PIN Name Signal Name Signal Description PIO Timing Timing Parameters Mode DMA Timing Ultra DMA Timing Mode MIN MAX Sustained 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 Features Register Error RegisterHost Software Interface Task File Registers Sector Number Register Sector Count RegisterCylinder Number Registers Device/Head Register Command Register Summary Command Name Command Code Parameters Used SDH Alternate Status Register Control Diagnostic RegistersDevice Control Register Digital Input Register Reset Handling Reset and Interrupt HandlingInterrupt Handling Set Feature Commands Interface Commands Read Sectors Read CommandsRead Verify Sectors Read Multiple Read DMA Set Multiple Mode Write CommandsWrite Sectors Write Verify Sectors Write DMA Write Multiple Set Features Mode Set Feature Commands Power Mode Commands Sleep Mode Identify Drive Initialization Commands 15-8 = PIO data transfer mode = Write Cache enabled Initialize Drive Parameters Execute Drive Diagnostic Seek, Format and Diagnostic CommandsFormat Track Execute S.M.A.R.T A.R.T. Command Set Service Policy Service and SupportNo Quibble Service Support Customer Service MaxFax ServiceInternet Glossary Access Time Cylinder Zero Gigabyte GB Logical Block Addressing Read Gate Signal THIN-FILM Media