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AT INTERFACE and ATA COMMANDS
6-
34 WA31273A / WA32543A / WA33203A / WA3216A / WA31083A / WA32162A
support block sizes of 2, 4, 8, and 16 sectors. Upon receipt of the command, the drive
sets BSY=1 and checks the Sector Count Register.
If the Sector Count Register contains a valid value and the block count is supported, the
value is loaded for all subsequent Read Multiple and Write Multiple commands and
execution of those commands is enabled. If a block count is not supported, an Aborted
Command error is posted, and Read Multiple and Write Multiple commands are
disabled.
If the Sector Count Register contains 0 when the command is issued, Read and Write
Multiple commands are disabled. At power on, or after a hardware reset, the default
mode is Read and Write Multiple disabled. And on software reset, the default mode of
Read and Write Multiple will not be changed.
6-4-19 Sleep (99h,E6h)
This command is the only way to cause the drive to enter Sleep Mode. The drive is spun
down, and when it is stopped, BSY is cleared, an interrupt is generated, and the
interface becomes inactive.
The only way to recover from Sleep mode without a reset or power on, is for the host to
issue a software reset.
A drive shall not power on in Sleep Mode nor remain in Sleep Mode following a reset
sequence. If the drive is already spun down, the spin down sequence is not executed.
6-4-20 Standby (96h,E2h)
This command causes the drive to set BSY, enter the Standby Mode, clear BSY, and
asserted INTRQ. INTRQ is isserted even though the device may not have fully
transitioned to Standby Mode.
If the Sector Count Register is non-zero, then the Standby Timer shall enabled. The value
in the Sector Count register shall be used to determine time programmed into the
Standby Mode.
The value in the Sector Count Register when the STANDBY command is issued shall
determine the time period programmed into the Standby Timer. See Table 6-7.
6-4-21 Standby Immediate (94h,E0h)
This command causes the drive to enter the Standby Mode. See 6.6.3 for protocol. The
drive may return the interrupt before the transition to Standby Mode is completed.
If the drive is already spun down, the spin down sequence is not executed.