HGST TRAVELSTAR 80GN 30GB ATA5 08K0910 User Manual

Travelstar 80GN Hard Disk Drive Specification

64 

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. See Section 10.12, "Status Register," on page 67 for the definition of the bits in this 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 58: , "Command Set (1 of 2)," on page 97 and Table 
59: , "Command Set (2 of 2)," on page 98. All other registers required for the command must be set up before writ-
ing to the Command Register. 

This register is used to transfer data blocks between the device data buffer and the host. It is also the register 
through which sector information is transferred on a Format Track command and the configuration information is 
transferred on an Identify Device command.

All data transfers are 16 bits wide, except for ECC byte transfers, which are 8 bits wide. Data transfers are PIO 
only.

The register contains valid data only when DRQ = 1 is in the Status Register.

7

6

5

4

3

2

1

0

BSY

RDY

DF

DSC

DRQ

COR

IDX

ERR