Hitachi HDT725025VLA380 Specifications - Page 119
SCT Command Protocol
UPC - 829686001084
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10.18.0.1 Capability definition Capability Identification is performed by issuing Identify Device command. Word 206 of Identify Data is used to determine if SCT is enabled and which SCT Action Codes are supported. Word 206 Description SCT Command set support 15-12 Vendor Specific 11-6 Reserved 5 Action Code 5 (SCT Data Table) supported 4 Action Code 4 (Features Control) supported 3 Action Code 2 (LBA Segment Access) supported 2 Action Code 2 (LBA Segment Access) supported 1 Action Code 1 (Long Sector Access) supported 0 SCT Feature Set supported (includes SCT status) 10.18.0.2 SCT Command Nesting and intermingling with Standard commands In general, standard ATA commands can be intermingled with SCT Commands but SCT commands cannot be nested. SCT commands that do not require a follow-on data transfer operation never have an issue with being intermixed with any ATA commands or each other. SCT commands that do require data transfer, on the other hand, may not be nested; that is, if a key command that requires a data transfer is issued, all data transfer - to or from the host - must complete before another SCT command is issued. In most cases, however, ATA read/write commands may be inserted in between SCT data transfers, that is, between complete SMART Read Log/Write Log commands. Furthermore, any reset (power-on, software or hardware) will cause the SCT command to be aborted. 10.18.0.3 Resets In an SCT command is executing, any reset including Soft Reset, Hard Reset, COMRESET, and Power-On Reset all cause the command to be terminated. This could result in partial command execution or data loss. There is no indication once the drive becomes ready that the previous command was terminated. 10.18.1 SCT Command Protocol Command Tansport SCT Command Transport occurs when a 512-byte data packet (called "Key Sector") is created and the written to SMART or extended log page E0h. The key sector specifies Action and Function Codes along with the parameters that are required to perform the action. 10.18.1.1 Issue SCT Command Using SMART Command Block Output Registers Register 7 6 5 4 3 2 1 0 Feature D6h Sector Count 01h Sector Number E0h Cylinder Low 4Fh Cylinder High C2h Device/Head ---D- -- Deskstar T7K500 Hard Disk Drive Specification 105