Hitachi 7K400 Specifications - Page 82
Alternate Status Register, Command Register, Cylinder High Register, Cylinder Low Register
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UPC - 000053412935
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9.2 Alternate Status Register Table 60: Alternate Status Register 7 6 5 4 3 2 1 0 BSY RDY DF DSC/ SERV DRQ COR IDX ERR This register contains the same information as the Status Register. The only difference between this register and the Status Register is that reading the Alternate Status Register does not imply an interrupt acknowledge or a clear of a pending interrupt. 9.3 Command Register This register contains the command code being sent to the device. Command execution begins immediately after this register is written. The command set is shown in Table 74: 'Command Set (1 of 2)" on page 109 and Table 75: 'Command Set (2 of 2)" on page 110. All other registers required for the command must be set up before writing to the Command Register. 9.4 Cylinder High Register This register contains the high order bits of the starting cylinder address for any disk access. At the end of the command, this register is updated to reflect the current cylinder number. In LBA Mode this register contains Bits 16-23. At the end of the command, this register is updated to reflect the current LBA Bits 16-23. The cylinder number may be from zero to the number of cylinders minus one. When 48-bit addressing commands are used, the "most recently written" content contains LBA Bits 16-23 and the "previous content" contains Bits 40-47. 9.5 Cylinder Low Register This register contains the low order 8 bits of the starting cylinder address for any disk access. At the end of the command, this register is updated to reflect the current cylinder number. In LBA Mode this register contains Bits 8-15. At the end of the command, this register is updated to reflect the current LBA Bits 8-15. The cylinder number may be from zero to the number of cylinders minus one (1). When 48-bit addressing commands are used, the "most recently written" content contains LBA Bits 8-15 and the "previous content" contains Bits 32-39. Deskstar 7K400 Hard Disk Drive Specification 68
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