"*" these signal lines are redifined during the Ultra DMA protocol to provide special
functions as detailed in the table below. These lines change from the conventional to special
definitions at the moment the host decides to allow a DMA burst, if the Ultra DMA transfer
mode was previously chosen via SetFeatures. The drive becomes aware of this change upon
assertion of the -DMACK line. These lines revert back to their original definitions upon the
deassertion of -DMACK at the termination of the DMA burst.
There are two input pins for +5 Volt power supply, "+5V Logic" and "+5V
Motor". "+5V Logic" is connected to the internal logic circuits and "+5V
Motor" is connected to the spindle motor and motor driver.
It is possible to turn on and off "+5V Logic" by an external switch circuit to
reduce power consumption to the least possible. In this mode, a voltage drop out due to the
motor spin up current can be reduced by connecting "+5V Motor" line into the
system power source directly.
If the above power management option is used, all signal lines that will be electrically
active in the host system while the hard disk drive is disconnected from power line shall be
isolated by three-state line drivers. Internal leakage through ESD protection circuit may pull
down LPUL (least positive up level) of logic signal below specification.
Use both lines in parallel, for regular hard disk drive applications.
| Special
Definition (Ultra DMA) |
Conventional
Definition |
| Write
Operation |
-DDMARDY |
IORDY |
| HSTROBE |
-DIOR |
| STOP |
-DIOW |
| Read
Operation |
-HDMARDY |
-DIOR |
| DSTROBE |
IORDY |
| STOP |
-DIOW |
