Samsung 3.5" hard disk drives User Manual

DISK DRIVE OPERATION 
 

SpinPoint V40 Product Manual 

42

 

 
This signal is active low to extend the host transfer cycle of any host register access (Read or Write) when the 
drive is not ready to respond to a data transfer request. When IORDY is not negated, this signal is in the high 
impedance state. 

 
This signal is asserted by Drive 1 to indicate to Drive 0 that it has completed diagnostics. A 10K pull-up 
resistor is used on this signal by each drive. 
 
Following a power-on reset, software reset, or RESET-, Drive 1 negates PDIAG- within 1 msec (to indicate 
to Drive 0 that it is busy). Drive 1 then asserts PDIAG- within 30 seconds to indicate that it is no longer busy 
and is able to provide status. After the assertion of PDIAG-, Drive 1 will be unable to accept commands until 
it has finished its reset procedure and is Ready (DRDY=1). 
 
Following the receipt of a valid Execute Drive Diagnostics command, Drive 1 negates PDIAG- within 1 
msec to indicate to Drive 0 that it is busy and has not yet passed its drive diagnostics. If Drive 1 is present, 
then Drive 0 waits for up to 5 seconds from the receipt of a valid Execute Drive Diagnostics command for 
Drive 1 to assert PDIAG-. Drive 1 clears BSY before asserting PDIAG-, as PDIAG- is used to indicate that 
Drive 1 has passed its diagnostics and is ready to post status. 
 
If DASP- was not asserted by Drive 1 during reset initialization, Drive 0 posts its own status immediately 
after it completes diagnostics, and clears the Drive 1 Status register to 00h. Drive 0 will be unable to accept 
commands until it has finished its reset procedure and is Ready (DRDY=1). 
 

 
This signal is asserted from the host system to reset the drive. It shall be asserted for at least 25 

µ

sec after 

voltage levels have stabilized during power-on; it is negated thereafter unless some event requires that the 
drive(s) be reset following power-on. 
 
Table 6-1 shows the correlation between the signals at the ATA interface and the host AT bus.