Maxtor VL 17 manual Read DMA, Read Multiple

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INTERFACECOMMANDS

Read DMA

Multi-word DMA

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

1.The host initializes a slave-DMA channel prior to issuing the command,

2.Data transfers are qualified by DMARQ and are performed by the slave-DMA channel and

3.The drive issues only one interrupt per command to indicate that data transfer has terminated and status is available.

Ultra DMA

With the Ultra DMA Read protocol, the control signal (DSTROBE) that latches data from DD(15:0) is generated by the devices which drives the data onto the bus. Ownership of DD(15:0) and this data strobe signal are given DSTROBE to the drive during an Ultra DMA data in burst.

During an Ultra DMA Read burst, the drive always moves data onto the bus, and, after a sufficient time to allow for propagation delay, cable settling, and setup time, the sender shall generate a DSTROBE edge to latch the data. Both edges of DSTROBE are used for data transfers.

Any unrecoverable error encountered during execution of a Read DMA command terminates data transfer after the transfer of all sectors prior to the sector where the error was detected. The sector in error is not transferred. The drive generates an interrupt to indicate that data transfer has terminated and status is available. The error posting is identical to the Read Sector(s) command.

Read Multiple

Performs similarly to the Read Sector(s) command, except that for each READ MULTIPLE command data transfers are multiple sector blocks and the Long bit is not valid.

Execution is also similar to that of the READ SECTOR(S) command, except that:

1.Several sectors are transferred to the host as a block, without intervening interrupts.

2.DRQ qualification of the transfer is required only at the start of each block, not of each sector.

The block count consists of the number of sectors to be transferred as a block. (The block count is programmed by the Set Multiple Mode command, which must be executed prior to the Read Multiple command.) READ LONG command is limited to single sector requests.

When the Read Multiple command is issued, the Sector Count register contains the number of sectors requested — not the number of blocks or the block count. If the number of sectors is not evenly divisible by the block count, as many full blocks as possible are transferred, followed by a final, partial block transfer. This final, partial block transfer is for N sectors, where N = (sector count) modulo (block count)

The Read Multiple operation will be rejected with an Aborted Command error if attempted:

1.Before the Set Multiple Mode command has been executed, or

2.When Read Multiple commands are disabled.

The controller reports disk errors encountered during Read Multiple commands at the start of the block or partial block transfer. However, DRQ still sets, and the transfer occurs normally, along with the transfer of any corrupt data. Remaining block data from the following the sector in error is not valid.

If the Sector Count register contains 0 when the Set Multiple Mode command is issued, Read Multiple and Write Multiple commands are disabled; no error is returned. Once the appropriate action has been taken, the controller resets BSY and generates an interrupt. At power up, or after a hardware or software reset, Read Multiple and Write Multiple commands are disabled by default.

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Contents HA RD Drive Produc T MA Nual DiamondMaxVL REV EC no Section Description Date U T I O N Before You BeginContents Handling and Installation Product SpecificationsHost Software Interface AT Interface DescriptionInterface Commands Service and SupportGlossary Figures Abbreviations IntroductionMaxtor Corporation Manual OrganizationNumbering Signal ConventionsConventions Key WordsProduct Description DiamondMax VL 17 Key FeaturesFunctional / Interface Product FeaturesOn-the-Fly Hardware Error Correction Code ECC Logical Block AddressingDefect Management Zone DMZ Cache Management Major HDA Components Dual Drive Support Subsystem ConfigurationJumper Location/Configuration Cylinder LimitationModels and Capacities Product SpecificationsDrive Configuration Performance SpecificationsParameter Standard Metric Physical DimensionsEnvironmental Limits Power RequirementsPower Mode Definitions EPA Energy Star ComplianceShock and Vibration Reliability SpecificationsSafety Regulatory Compliance Radiated Electromagnetic Field Emissions EMC ComplianceCanadian Emissions Statement Important Notice Handling and InstallationHard Drive Handling Precautions Pre-formatted DriveMulti-pack Shipping Container Unpacking and InspectionPhysical Installation Recommended Mounting ConfigurationRepacking Drive Identification Information Handling PrecautionsTools for Installation System RequirementsHard Drive Identification General RequirementsMounting Drive in System Systems Using Cable SelectInstalling 5.25-inch Mounting Brackets and Rails Installing in a Device BayAttaching System Cables Attaching Interface and Power CablesSystem Setup Setting the Bios CmosBios Cmos Parameters Hard Drive Preparation System Hangs During Boot Pin Description Summary Interface ConnectorPIN Signal AT Interface DescriptionPin Description Table PIN Name Signal Name Signal DescriptionPIO Timing Timing Parameters ModeDMA Timing Ultra DMA Timing Mode MIN MAXSustained 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 Task File Registers Error RegisterFeatures Register Host Software InterfaceDevice/Head Register Sector Count RegisterSector Number Register Cylinder Number RegistersCommand Register Command Name Command Code Parameters Used Timer Value TIME-OUT PeriodSummary Digital Input Register Control Diagnostic RegistersAlternate Status Register Device Control RegisterReset and Interrupt Handling Reset HandlingInterrupt Handling Set Feature Commands Interface CommandsRead Commands Read SectorsRead Verify Sectors Read Multiple Read DMAWrite Verify Sectors Write CommandsSet Multiple Mode Write SectorsWrite DMA Write MultipleSet Feature Commands Set Features ModeValue Description Power Mode Commands Sleep Mode Initialization Commands Word Content DescriptionIdentify Drive 15-8 = PIO data transfer mode = Write Cache enabled Initialize Drive Parameters Format Track Seek, Format and Diagnostic CommandsExecute Drive Diagnostic Error Code DescriptionExecute S.M.A.R.T A.R.T. Command SetSupport Service and SupportService Policy No Quibble ServiceMaxFax Service Customer ServiceInternet Glossary Access TimeCylinder Zero Gigabyte GB Logical Block Addressing Read Gate Signal THIN-FILM Media
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