Standby Timer; Status; Interface Capability For Power Modes; Initial Power Mode At Power On - Hitachi IC25N040ATCS04-0 - Travelstar 40GN 40GB UDMA/100 4200RPM 2MB 2.5" IDE Hard Drive Specifications

11.6.4 Standby timer

The standby timer provides a method for the device to automatically enter standby mode from either
active or idle mode following a host programmed period of inactivity. If the device is in the active or idle
mode, the device waits for the specified time period and if no command is received, the device automa-
tically enters the standby mode.
If the value of the SECTOR COUNT register on Idle command or the Standby command is set to "00h",
the device will automatically set the standby timer to 109 minutes.

11.6.5 Status

In the active, idle, and standby modes, the device shall have the RDY bit of the status register set. If the
BSY bit is not set, the device shall be ready to accept any command.
In sleep mode, the device's interface is not active. A host shall not attempt to read the status of the device
or issue commands to the device.

11.6.6 Interface Capability for Power Modes

Each power mode affects the physical interface as defined in the following table:
Mode
Active
Idle
Standby
Sleep

Figure 62. Power conditions

Ready (RDY) is not a power condition. A device may post ready at the interface even though the media
may not be accessible.
The interface is inactive in sleep mode, but the access to the interface registers and the validity of INTRQ
is guaranteed for two seconds after the Sleep command is completed. After this period, the contents of
interface registers may be lost. Since the contents of interface registers may be invalid, the host should
NOT check the Status register nor the Alternate Status register prior to issuing a soft reset to wake up a
device.

11.6.7 Initial Power Mode at Power On

After power on or hard reset the device goes to IDLE mode or STANDBY mode depending on the option.
Refer to section 4.4.3, "Operating Modes" on page 17 for the initial power mode selection.
BSY RDY
x x
o 1
o 1
x x
Hitachi Travelstar 60GH & 40GN hard disk drive specifications
Interface
active
Yes
Yes
Yes Inactive
No Inactive
81
Media
Active
Active