Hitachi HTS421210H9AT00, Specifications

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Travelstar 4K120 Hard Disk Drive Specification
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11.15 48-bit Address Feature Set
The 48-bit Address feature set allows devices with capacities up to 281,474,976,710,655 sectors. This allows device
capacity up to 144,115,188,075,855,360 bytes. In addition, the number of sectors that may be transferred by a single
command are increased by increasing the allowable sector count to 16 bits.
Commands unique to the 48-bit Address feature set are:
• Flush Cache Ext
• Read DMA Ext
• Read Multiple Ext
• Read Native Max Address Ext
• Read Sector(s) Ext
• Read Verify Sector(s) Ext
• Set Max Address Ext
• Write DMA Ext
• Write Multiple Ext
• Write DMA FUA Ext
• Write Sector(s) Ext
• Write Multiple FUA Ext
The 48-bit Address feature set operates in LBA addressing only. Devices also implement commands using 28-bit
addressing, and 28-bit and 48-bit commands may be intermixed.
In a device, the Features, the Sector Count, the LBA Low/Mid/High registers are a two-byte-deep FIFO. Each time
one of these registers is written, the new content written is placed into the "most recently written" location and the
previous content is moved to "previous content" location.
The host may read the "previous content" of the Features, the Sector Count, the LBA Low/Mid/High registers by
first setting the High Order Bit (HOB, bit 7) of the Device control register to one and then reading the desired
register. If HOB in the Device Control register is cleared to zero, the host reads the "most recently written" content
when the register is read. A write to any Command Block register shall cause the device to clear the HOB bit to zero
in the Device Control register. The "most recently written" content always gets written by a register write regardless
of the state of HOB in the Device Control register.
Support of the 48-bit Address feature set is indicated in the Identify Device response bit 10 word 83. In addition, the
maximum user LBA address accessible by 48-bit addressable commands is contained in Identify Device response
words 100 through 103.
When the 48-bit Address feature set is implemented, the native maximum address is the value returned by a Read
Native Max Address Ext command. If the native maximum address is equal to or less than 268,435,455, a Read
Native Max Address shall return the native maximum address. If the native maximum address is greater than
268,435,455, a Read Native Max Address shall return a value of 268,435,455.