diff options
Diffstat (limited to 'sys/doc/ata/ata-9')
| -rw-r--r-- | sys/doc/ata/ata-9 | 721 |
1 files changed, 721 insertions, 0 deletions
diff --git a/sys/doc/ata/ata-9 b/sys/doc/ata/ata-9 new file mode 100644 index 000000000000..4cd3f6684989 --- /dev/null +++ b/sys/doc/ata/ata-9 @@ -0,0 +1,721 @@ +9. Command Descriptions + +Commands are issued to the drive by loading the pertinent registers in the +command block with the needed parameters, and then writing the command code to +the Command Register. + +The manner in which a command is accepted varies. There are three classes +(see Table 9-1) of command acceptance, all predicated on the fact that to +receive a command, BSY=0: + + - Upon receipt of a Class 1 command, the drive sets BSY within 400 nsec. + - Upon receipt of a Class 2 command, the drive sets BSY within 400 nsec, sets + up the sector buffer for a write operation, sets DRQ within 700 usec, and + clears BSY within 400 nsec of setting DRQ. + - Upon receipt of a Class 3 command, the drive sets BSY within 400 nsec, sets + up the sector buffer for a write operation, sets DRQ within 20 msec, and + clears BSY within 400 nsec of setting DRQ. + +..rm102 + NOTE: DRQ may be set so quickly on Class 2 and Class 3 that the BSY + transition is too short for BSY=1 to be recognized. + +The drive shall implement all mandatory commands as identified by an M, and +may implement the optional commands identified by an O, in Table 9-1. V +indicates a Vendor Specific command code. + + TABLE 9-1: COMMAND CODES AND PARAMETERS + +-------+-------------------+ + +-----+ |Command| Parameters Used | + |Class| | Code |FR SC SN CY DH | + +-----+----------------------------------+---+-------+---+---+---+---+---+ + | 1 | Check Power Mode | O |98h E5h| | y | | | D | + | 1 | Execute Drive Diagnostic | M | 90h | | | | | D*| + | 2 | Format Track | M | 50h | * | y | | y | y | + | 1 | Identify Drive | O | ECh | | | | | D | + | 1 | Idle | O |97h E3h| | y | | | D | + | 1 | Idle Immediate | O |95h E1h| | | | | D | + | 1 | Initialize Drive Parameters | M | 91h | | y | | | y | + | 1 | Recalibrate | M | 1xh | | | | | D | + | 1 | Read Buffer | O | E4h | | | | | D | + | 1 | Read DMA (w/retry) | O | C8h | | y | y | y | y | + | 1 | Read DMA (w/o retry) | O | C9h | | y | y | y | y | + | 1 | Read Multiple | O | C4h | | y | y | y | y | + | 1 | Read Sector(s) (w/retry) | M | 20 | | y | y | y | y | + | 1 | Read Sector(s) (w/o retry) | M | 21 | | y | y | y | y | + | 1 | Read Long (w/retry) See 9.13 | M | 22 | | y | y | y | y | + | 1 | Read Long (w/o retry) See 9.13 | M | 23 | | y | y | y | y | + | 1 | Read Verify Sector(s) (w/retry) | M | 40 | | y | y | y | y | + | 1 | Read Verify Sector(s) (w/o retry)| M | 41 | | y | y | y | y | + | 1 | Seek | M | 7xh | | | y | y | y | + | 1 | Set Features | O | EFh | y | | | | D | + | 1 | Set Multiple Mode | O | C6h | | y | | | D | + | 1 | Set Sleep Mode | O |99h E6h| | | | | D | + | 1 | Standby | O |96h E2h| | y | | | D | + | 1 | Standby Immediate | O |94h E0h| | | | | D | + | 2 | Write Buffer | O | E8h | | | | | D | + | 3 | Write DMA (w/retry) | O | CAh | | y | y | y | y | + | 3 | Write DMA (w/o retry) | O | CBh | | y | y | y | y | + | 3 | Write Multiple | O | C5h | * | y | y | y | y | + | 3 | Write Same | O | E9h | y | y | y | y | y | + | 2 | Write Sector(s) (w/retry) | M | 30 | * | y | y | y | y | + | 2 | Write Sector(s) (w/o retry) | M | 31 | * | y | y | y | y | + | 2 | Write Sector(s) (w/retry) | M | 32 | * | y | y | y | y | + | 2 | Write Sector(s) (w/o retry) | M | 33 | * | y | y | y | y | + | 3 | Write Verify | O | 3Ch | * | y | y | y | y | + | | Vendor Unique | V | 9Ah | | | | | | + | | Vendor Unique | V | C0-C3h| | | | | | + | | Vendor Unique | V | 8xh | | | | | | + | | Vendor Unique | V |F5h-FFh| | | | | | + | | EATA Standard (CAM/89-004) | O |F0h-F4h| | | | | | + | | Reserved: All remaining codes | | | | | | | | + +-----+----------------------------------+---+-------+---+---+---+---+---+ + | | CY = Cylinder Registers SC = Sector Count Register | + | | DH = Drive/Head Register SN = Sector Number Register | + | | FR = Features Register (see command descriptions for use) | +.. | | | +.. | | M = Mandatory O = Optional V = Vendor Specific | + | | y - the register contains a valid parameter for this command. | + | | For the Drive/Head Register, y means both the drive and | + | | head parameters are used. | + | | D - only the drive parameter is valid and not the head parameter.| + | | D* - Addressed to Drive 0 but both drives execute it. | + | | * - Maintained for compatibility (see 7.2.9) | + +-----+------------------------------------------------------------------+ + +9.1 Check Power Mode + +This command checks the power mode. + +If the drive is in, going to, or recovering from the Standby Mode the drive +shall set BSY, set the Sector Count Register to 00h, clear BSY, and generate +an interrupt. + +If the drive is in the Idle Mode, the drive shall set BSY, set the Sector +Count Register to FFh, clear BSY, and generate an interrupt. + +9.2 Execute Drive Diagnostic + +This command shall perform the internal diagnostic tests implemented by the +drive. See also 6.3.4 and 6.3.13. The DRV bit is ignored. Both drives, if +present, shall execute this command. + +If Drive 1 is present: + + - Drive 0 waits up to 5 seconds for Drive 1 to assert PDIAG-. + - If Drive 1 has not asserted PDIAG-, indicating a failure, Drive 0 shall + append 80h to its own diagnostic status. + - Both drives shall execute diagnostics. + - If Drive 1 diagnostic failure is detected when Drive 0 status is read, + Drive 1 status is obtained by setting the DRV bit, and reading status. + +If there is no Drive 1 present: + + - Drive 0 posts only its own diagnostic results. + - Drive 0 clears BSY, and generates an interrupt. + +The Diagnostic Code written to the Error Register is a unique 8-bit code as +shown in Table 9-2, and not as the single bit flags defined in 7.2.9. + +..Table 9-2 details the codes and the corresponding explanations. +If Drive 1 fails diagnostics, Drive 0 "ORs" 80h with its own status and loads +that code into the Error Register. If Drive 1 passes diagnostics or there is +no Drive 1 connected, Drive 0 "ORs" 00h with its own status and loads that +code into the Error Register. + + TABLE 9-2: DIAGNOSTIC CODES + +-------+ + | Code | + +-------+----------------------------------+ + | 01h | No error detected | + | 02h | Formatter device error | + | 03h | Sector buffer error | + | 04h | ECC circuitry error | + | 05h | Controlling microprocessor error | + | 8xh | Drive 1 failed | + +-------+----------------------------------+ + +9.3 Format Track + +The implementation of the Format Track command is vendor specific. The actions +may be a physical reformatting of a track, initializing the data field +contents to some value, or doing nothing. + +The Sector Count Register contains the number of sectors per track. + +The track address is specified in the Cylinder High and Cylinder Low +Registers, and the number of sectors is specified in the Sector Count +Register. When the command is accepted, the drive sets the DRQ bit and waits +for the host to fill the sector buffer. When the sector buffer is full, the +drive clears DRQ, sets BSY and begins command execution. + +The contents of the sector buffer shall not be written to the media, and may +be either ignored or interpreted as follows: + + DD15 ---- DD0 DD15 ---- DD0 + +------+------+ +------+------+--------------------------+ + | First|Desc- | | Last |Desc- | Remainder of buffer | + |Sector|riptor| : : : : : : |Sector|riptor| filled with zeros | + +------+------+ +------+------+--------------------------+ + +One 16-bit word represents each sector, the words being contiguous from the +start of a sector. Any words remaining in the buffer after the representation +of the last sector are filled with zeros. DD15-8 contain the sector number. If +an interleave is specified, the words appear in the same sequence as they +appear on the track. DD7-0 contain a descriptor value defined as follows: + + 00h - Format sector as good + 20h - Unassign the alternate location for this sector + 40h - Assign this sector to an alternate location + 80h - Format sector as bad + +..rm102 + NOTE: Some users of the ATA drive expect the operating system partition + table to be erased on a Format command. It is recommended that a drive + which does not perform a physical format of the track, write a data + pattern of all zeros to the sectors which have been specified by the + Format Track command. + +..rm102 + NOTE: It is recommended that implementors resassign data blocks which show + repeated errors. + +9.4 Identify Drive + +The Identify Drive command enables the host to receive parameter information +from the drive. When the command is issued, the drive sets BSY, stores the +required parameter information in the sector buffer, sets DRQ, and generates +an interrupt. The host then reads the information out of the sector buffer. +The parameter words in the buffer have the arrangement and meanings defined in +Table 9-3. All reserved bits or words shall be zero. + + +-------+ TABLE 9-3: IDENTIFY DRIVE INFORMATION + | Word | + +-------+------------------------------------------------------------------+ + | 0 | General configuration bit-significant information: | + | | 15 0 reserved for non-magnetic drives | + | | 14 1=format speed tolerance gap required | + | | 13 1=track offset option available | + | | 12 1=data strobe offset option available | + | | 11 1=rotational speed tolerance is > 0.5% | + | | 10 1=disk transfer rate > 10 Mbs | + | | 9 1=disk transfer rate > 5Mbs but <= 10Mbs | + | | 8 1=disk transfer rate <= 5Mbs | + | | 7 0 reserved for removable cartridge drive | + | | 6 1=fixed drive | + | | 5 1=spindle motor control option implemented | + | | 4 1=head switch time > 15 usec | + | | 3 1=not MFM encoded | + | | 2 1=soft sectored | + | | 1 1=hard sectored | + | | 0 0=reserved | + | 1 | Number of fixed cylinders | + | 2 | reserved | + | 3 | Number of heads | + | 4 | Number of unformatted bytes per track | + | 5 | Number of unformatted bytes per sector | + | 6 | Number of sectors per track | + | 7-9 | Vendor Unique | + | 10-19 | Serial number (20 ASCII characters, 0000h=not specified) | + | 20 | Buffer type | + | 21 | Buffer size in 512 byte increments (0000h=not specified) | + | 22 | # of ECC bytes passed on Read/Write Long cmds (0000h=not spec'd) | + | 23-26 | Firmware revision (8 ASCII characters, 0000h=not specified) | + | 27-46 | Model number (40 ASCII characters, 0000h=not specified) | + | 47 | 0000h = Read/Write Multiple commands not implemented | + | | x = number of sectors that can be transferred per interrupt | + | | on Read and Write Multiple commands | + | 48 | 0000h = cannot perform doubleword I/O | + | | 0001h = can perform doubleword I/O | + | 49 | Capabilities | + | | 15-9 0=reserved | + | | 8 1=DMA Supported | + | | 7-0 Vendor Unique | + | 50 | reserved | + | 51 | PIO data transfer cycle timing mode | + | 52 | DMA data transfer cycle timing mode | + | 53-127| reserved | + |128-159| Vendor Unique | + |160-255| reserved | + +-------+------------------------------------------------------------------+ + +The fields described in 9.4.1 through 9.4.5 are not affected by the Initialize +Drive Parameters command. + +9.4.1 Number of fixed cylinders + +The number of translated cylinders in the default translation mode. + +9.4.2 Number of heads + +The number of translated heads in the default translation mode. + +9.4.3 Number of unformatted bytes per track + +The number of unformatted bytes per translated track in the default +translation mode. + +9.4.4 Number of unformatted bytes per sector + +The number of unformatted bytes per sector in the default translation mode. + +9.4.5 Number of sectors per track + +The number of sectors per track in the default translation mode. + +9.4.6 Serial Number + +The contents of this field are right justified and padded with spaces (20h). + +9.4.7 Buffer Type + +The contents of the field are determined by the manufacturer. + + 0000h = not specified. + 0001h = a single ported single sector buffer which is not capable of + simultaneous data transfers to or from the host and the disk. + 0002h = a dual ported multi-sector buffer capable of simultaneous data + transfers to or from the host and the disk. + 0003h = a dual ported multi-sector buffer capable of simultaneous transfers + with a read cacheing capability. + 0004-FFFFh = reserved + +These codes are typically not used by the operating system, however, they are +useful for diagnostic programs which perform initialization routines e.g. a +different interleave may be desirable for 0001h vs 0002h or 0003h. + +9.4.8 Firmware Revision + +The contents of this field are left justified and padded with spaces (20h). + +9.4.9 Model Number + +The contents of this field are left justified and padded with spaces (20h). + +9.4.10 PIO data transfer cycle timing mode + +The PIO transfer timing for each ATA device falls into categories which have +unique parametric timing specifications. To determine the proper device timing +category, compare the Cycle Time specified in Figure 11-1 with the contents of +this field. The value returned should fall into one of the categories +specified in Figure 11-1, and if it does not, then Mode 0 shall be used to +serve as the default timing. + +9.4.11 DMA data transfer cycle timing mode + +The DMA transfer timing for each ATA device falls into categories which have +unique parametric timing specifications. To determine the proper device timing +category, compare the Cycle Time specified in Figure 11-3 with the contents of +this field. The value returned should fall into one of the categories +specified in Figure 11-3, and if it does not, then Mode 0 shall be used to +serve as the default timing. + +9.5 Idle + +This command causes the drive to set BSY, enter the Idle Mode, clear BSY, and +generate an interrupt. The interrupt is generated even though the drive may +not have fully transitioned to Idle Mode. + +If the drive is already spinning, the spinup sequence is not executed. + +If the Sector Count Register is non-zero then the automatic power down +sequence shall be enabled and the timer begins counting down immediately. If +the Sector Count Register is zero then the automatic power down sequence shall +be disabled. + +9.6 Idle Immediate + +This command causes the drive to set BSY, enter the Idle Mode, clear BSY, and +generate an interrupt. The interrupt is generated even though the drive may +not have fully transitioned to Idle Mode. + +9.7 Initialize Drive Parameters + +..This command enables the host to control certain drive parameters. Some +..parameters are standard while others are vendor specific. +This command enables the host to set the number of sectors per track and the +number of heads minus 1, per cylinder. Upon receipt of the command, the drive +sets BSY, saves the parameters, clears BSY, and generates an interrupt. + +The only two register values used by this command are the Sector Count +Register which specifies the number of sectors per track, and the Drive/Head +Register which specifies the number of heads minus 1. The DRV bit designates +these values to Drive 0 or Drive 1, as appropriate. + +The sector count and head values are not checked for validity by this command. +If they are invalid, no error will be posted until an illegal access is made +by some other command. + +9.8 Recalibrate + +This command moves the read/write heads from anywhere on the disk to cylinder +0. Upon receipt of the command, the drive sets BSY and issues a seek to +cylinder zero. The drive then waits for the seek to complete before updating +status, clearing BSY and generating an interrupt. + +If the drive cannot reach cylinder 0, a Track Not Found error is posted. + +9.9 Read Buffer + +The Read Buffer command enables the host to read the current contents of the +drive's sector buffer. When this command is issued, the drive sets BSY, sets +up the sector buffer for a read operation, sets DRQ, clears BSY, and generates +an interrupt. The host then reads up to 512 bytes of data from the buffer. + +The Read Buffer and Write Buffer commands shall be synchronized such that +sequential Write Buffer and Read Buffer commands access the same 512 bytes +within the buffer. + +9.10 Read DMA + +This command executes in a similar manner to the Read Sectors command except +for the following: + + - the host initializes a slave-DMA channel prior to issuing the command + - data transfers are qualified by DMARQ and are performed by the slave-DMA + channel + - the drive issues only one interrupt per command to indicate that data + transfer has terminated and status is available. + +Any error encountered during execution of a Read DMA command results in the +termination of data transfer at 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 the same as that of the Read Sectors command. + +9.11 Read Long + +The Read Long command performs similarly to the Read Sectors command except +that it returns the data and the ECC bytes contained in the data field of the +desired sector. During a Read Long command, the drive does not check the ECC +bytes to determine if there has been a data error. Only single sector read +long operations are supported. + +The transfer of the ECC bytes shall be 8-bits wide. + +9.12 Read Multiple Command + +The Read Multiple command performs similarly to the Read Sectors command. +Interrupts are not generated on every sector, but on the transfer of a block +which contains the number of sectors defined by a Set Multiple command. + +Command execution is identical to the Read Sectors operation except that the +number of sectors defined by a Set Multiple command are transferred without +intervening interrupts. DRQ qualification of the transfer is required only at +the start of the data block, not on each sector. + +The block count of sectors to be transferred without intervening interrupts is +programmed by the Set Multiple Mode command, which shall be executed prior to +the Read Multiple command. + +When the Read Multiple command is issued, the Sector Count Register contains +the number of sectors (not the number of blocks or the block count) requested. + +If the number of requested sectors is not evenly divisible by the block count, +as many full blocks as possible are transferred, followed by a final, partial +block transfer. The partial block transfer shall be for n sectors, where + + n = (sector count) - modulo (block count) + +If the Read Multiple command is attempted before the Set Multiple Mode command +has been executed or when Read Multiple commands are disabled, the Read +Multiple operation shall be rejected with an Aborted Command error. + +Disk errors encountered during Read Multiple commands are posted at the +beginning of the block or partial block transfer, but DRQ is still set and the +data transfer shall take place as it normally would, including transfer of +corrupted data, if any. + +The contents of the Command Block Registers following the transfer of a data +block which had a sector in error are undefined. The host should retry the +transfer as individual requests to obtain valid error information. + +Subsequent blocks or partial blocks are transferred only if the error was a +correctable data error. All other errors cause the command to stop after +transfer of the block which contained the error. Interrupts are generated when +DRQ is set at the beginning of each block or partial block. + +..The error reporting is the same as that on a Read Sectors command. +.. +9.13 Read Sector(s) + +This command reads from 1 to 256 sectors as specified in the Sector Count +register. A sector count of 0 requests 256 sectors. The transfer begins at the +sector specified in the Sector Number Register. See 10.1 for the DRQ, IRQ and +BSY protocol on data transfers. + +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 appropriate +ID field. + +If retries are disabled and two index pulses have occurred without error free +reading of the requested ID, an ID Not Found error is posted. + +If retries are enabled, up to a vendor specific number of attempts may be made +to read the requested ID before posting an error. + +If the ID is read correctly, the data address mark shall be recognized within +a specified number of bytes, or the Address Mark Not Found error is posted. + +..Once the data address mark is found, the data field is read into the sector +..buffer, error bits are set if an error was encountered, DRQ is set, and an +..interrupt is generated. +.. +DRQ is always set regardless of the presence or absence of an error condition +at the end of the sector. + +At command completion, the Command Block Registers contain the cylinder, head, +and sector number of the last sector read. + +If an error occurs, the read terminates at the sector where the error +occurred. The Command Block Registers contain the cylinder, head, and sector +number of the sector where the error occurred. + +The flawed data is pending in the sector buffer. + +9.14 Read Verify Sector(s) + +This command is identical to the Read Sectors command, except that DRQ is +never set, and no data is transferred to the host. See 10.3 for protocol. +..When the command is accepted, the drive sets BSY. + +When the requested sectors have been verified, the drive clears BSY and +generates an interrupt. Upon command completion, the Command Block Registers +contain the cylinder, head, and sector number of the last sector verified. + +If an error occurs, the verify terminates at the sector where the error +occurs. The Command Block Registers contain the cylinder, head, and sector +number of the sector where the error occurred. The Sector Count Register shall +contain the number of sectors not yet verified. + +9.15 Seek + +This command initiates a seek to the track and selects the head specified in +the command block. The drive need not be formatted for a seek to execute +properly. See 10.3 for protocol. The drive shall not set DSC=1 until the +action of seeking has completed. The drive may return the interrupt before the +seek is completed. + +If another command is issued to the drive while a seek is being executed, the +drive sets BSY=1, waits for the seek to complete, and then begins execution of +the command. + +..The Sector Number Register is used to translate between perceived and real +..geometry. +.. +9.16 Set Features + +This command is used by the host to establish the following parameters which +affect the execution of certain drive features: + + 44h Vendor unique length of ECC on Read Long/Write Long commands + 55h Disable read look-ahead feature + AAh Enable read look-ahead feature + BBh 4 bytes of ECC apply on Read Long/Write Long commands + +See 10.3 for protocol. If the value in the register is not supported or is +invalid, the drive posts an Aborted Command error. + +At power on, or after a software or hardware reset, the default mode is read +look-ahead enabled and 4 bytes of ECC. + +9.17 Set Multiple Mode + +This command enables the drive to perform Read and Write Multiple operations +and establishes the block count for these commands. See 10.3 for protocol. + +The Sector Count Register is loaded with the number of sectors per block. +Drives shall support block sizes of 2, 4, 8, and 16 sectors, if their buffer +size is at least 8,192 bytes, and may also support other block sizes. Upon +receipt of the command, the drive sets BSY=1 and checks the Sector Count +Register. + +If the Sector Count Register contains a valid value and the block count is +supported, the value is loaded for all subsequent Read Multiple and Write +Multiple commands and execution of those commands is enabled. If a block count +is not supported, an Aborted Command error is posted, and Read Multiple and +Write Multiple commands are disabled. + +If the Sector Count Register contains 0 when the command is issued, Read and +Write Multiple commands are disabled. + +At power on, or after a hardware or software reset, the default mode is Read +and Write Multiple disabled. + +9.18 Sleep + +This command is the only way to cause the drive to enter Sleep Mode. The drive +is spun down, and when it is stopped, BSY is cleared, an interrupt is +generated, and the interface becomes inactive. + +The only way to recover from Sleep mode without a reset or power on, is for +the host to issue a software reset. + +A drive shall not power on in Sleep Mode nor remain in Sleep Mode following a +reset sequence. If the drive is already spun down, the spin down sequence is +not executed. + +9.19 Standby + +This command causes the drive to enter the Standby Mode. See 10.3 for +protocol. The drive may return the interrupt before the transition to Standby +Mode is completed. + +If the drive is already spun down, the spin down sequence is not executed. + +If the Sector Count Register is non-zero then the automatic power down +sequence shall be enabled and the timer will begin counting down when the +drive returns to Idle mode. If the Sector Count Register is zero then the +automatic power down sequence shall be disabled. + +9.20 Standby Immediate + +This command causes the drive to enter the Standby Mode. See 10.3 for +protocol. The drive may return the interrupt before the transition to Standby +Mode is completed. + +If the drive is already spun down, the spin down sequence is not executed. + +9.21 Write Buffer + +This command enables the host to overwrite the contents of the drive's sector +buffer with any data pattern desired. See 10.2 for protocol. + +The Read Buffer and Write Buffer commands shall be synchronized within the +drive such that sequential Write Buffer and Read Buffer commands access the +same 512 bytes within the buffer. + +9.22 Write DMA + +This command executes in a similar manner to Write Sectors except for the +following: + + - the host initializes a slave-DMA channel prior to issuing the command + - data transfers are qualified by DMARQ and are performed by the slave-DMA + channel + - the drive issues only one interrupt per command to indicate that data + transfer has terminated and status is available. + +Any error encountered during Write DMA execution results in the termination of +data transfer. The drive issues an interrupt to indicate that data transfer +has terminated and status is available in the Error Register. The error +posting is the same as that of the Write Sectors command. + +9.23 Write Multiple Command + +This command is similar to the Write Sectors command. The drive sets BSY +within 400 nsec of accepting the command, and interrupts are not presented on +each sector but on the transfer of a block which contains the number of +sectors defined by Set Multiple. + +Command execution is identical to the Write Sectors operation except that the +number of sectors defined by the Set Multiple command are transferred without +intervening interrupts. DRQ qualification of the transfer is required only at +the start of the data block, not on each sector. + +The block count of sectors to be transferred without intervening interrupts is +programmed by the Set Multiple Mode command, which shall be executed prior to +the Read Multiple command. + +When the Write Multiple command is issued, the Sector Count Register contains +the number of sectors (not the number of blocks or the block count) requested. + +If the number of requested sectors is not evenly divisible by the block count, +as many full blocks as possible are transferred, followed by a final, partial +block transfer. The partial block transfer is for n sectors, where + + n = (sector count) - modulo (block count) + +If the Write Multiple command is attempted before the Set Multiple Mode +command has been executed or when Write Multiple commands are disabled, the +Write Multiple operation shall be rejected with an aborted command error. + +Disk errors encountered during Write Multiple commands are posted after the +attempted disk write of the block or partial block transferred. The Write +command ends with the sector in error, even if it was in the middle of a +block. Subsequent blocks are not transferred in the event of an error. +Interrupts are generated when DRQ is set at the beginning of each block or +partial block. + +..The Command Block Registers contain the cylinder, head, and sector number of +..the sector where the error occurred and the Sector Count Register contains the +..residual of sectors that need to be transferred for successful completion of +..the command e.g. each block has 4 sectors, a request for 8 sectors is issued, +..and an error occurs on the third sector. The Sector Count Register contains 6 +..and the address is that of the third sector. +.. +The contents of the Command Block Registers following the transfer of a data +block which had a sector in error are undefined. The host should retry the +transfer as individual requests to obtain valid error information. + +9.24 Write Same + +This command executes in a similar manner to Write Sectors except that only +one sector of data is transferred. The contents of the sector are written to +the medium one or more times. + +NOTE: The Write Same command allows for initialization of part or all of the +medium to the specified data with a single command. + +If the Features Register is 22h, the drive shall write that part of the medium +specified by the sector count, sector number, cylinder and drive/head +registers. If the Features Register contains DDh, the drive shall initialize +all the user accessible medium. If the register contains a value other than +22h or DDh, the command shall be rejected with an aborted command error. + +The drive issues an interrupt to indicate that the command is complete. Any +error encountered during execution results in the termination of the write +operation. Status is available in the Error Register if an error occurs. The +error posting is the same as that of the Write Sectors command. + +9.25 Write Long + +This command is similar to the Write Sectors command except that it writes the +data and the ECC bytes directly from the sector buffer; the drive does not +generate the ECC bytes itself. Only single sector Write Long operations are +supported. + +The transfer of the ECC bytes shall be 8-bits wide. + +9.26 Write Sector(s) + +This command writes from 1 to 256 sectors as specified in the Sector Count +Register (a sector count of zero requests 256 sectors), beginning at the +specified sector. See 10.1 for the DRQ, IRQ and BSY protocol on data +transfers. + +..When this command is accepted, the drive sets DRQ and waits +..for the host to fill the sector buffer with the data to be written. No +..interrupt is generated to start the first buffer fill operation. Once the +..buffer is full, the drive clears DRQ, sets BSY and begins command execution. +.. +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 appropriate +ID field. + +If retries are disabled and two index pulses have occurred without error free +reading of the requested ID, an ID Not Found error is posted. + +If retries are enabled, up to a vendor specific number of attempts may be made +to read the requested ID before posting an error. + +If the ID is read correctly, the data loaded in the buffer is written to the +data field of the sector, followed by the ECC bytes. Upon command completion, +the Command Block Registers contain the cylinder, head, and sector number of +the last sector written. + +If an error occurs during a write of more than one sector, writing terminates +at the sector where the error occurs. The Command Block Registers contain the +cylinder, head, and sector number of the sector where the error occurred. The +host may then read the command block to determine what error has occurred, and +on which sector. + +9.27 Write Verify + +This command is similar to the Write Sectors command, except that each sector +is verified immediately after being written. The verify operation is a read +without transfer and a check for data errors. Any errors encountered during +the verify operation are posted. Multiple sector write verify commands write +all the requested sectors and then verify all the requested sectors before +generating the final interrupt. + |