Samsung 3.5" hard disk drives Manual Do Utilizador

DISK DRIVE OPERATION 

 

SpinPoint V40 Product Manual

83

 

 
Commands can be grouped into different classes according to the protocols followed for command execution.  
The command classes with their associated protocols are defined below. 
 
For all commands, the host first checks if BSY=1, and should proceed no further unless and until BSY=0. 
For most commands, the host will also wait for DRDY=1 before proceeding. Those commands shown with 
DRDY=X can be executed when DRDY=0. 
 
 

 
This class includes: 
 

•

  Identify Drive (ECh) 

•

  Read Buffer (E4h) 

•

  Read Long (22h) 

•

  Read Multiple (C4h) 

•

  Read Sector(s) (20h) 

•

  SMART Read Data 

•

  SMART Read Log Sector 

 
Execution includes the transfer of one or more 512 byte (>512 bytes on Read Long) sectors of data from the 
drive to the host. 
 
a)  The host writes any required parameters to the Features, Sector Count, Sector Number, Cylinder and 

Drive/Head registers. 

 
b)   The host writes the command code to the Command register. 
 
c)   The drive sets BSY and prepares for data transfer. 
 
d)  When a sector of data is available, the drive sets DRQ and clears BSY prior to asserting INTRQ. 
 
e)   After detecting INTRQ, the host reads the Status register, then reads on sector of data via the Data 

register. In response to the Status register being read, the drive negates INTRQ. 

 
f)   The drive clears DRQ. If transfer of another sector is required, the drive also sets BSY and the above 

sequence is repeated from (d).