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5.3 Host Commands
C141-E218 5-91
Multiword DMA transfer mode X 00100 000 (X’20’: Mode 0)
00100 001 (X’21’: Mode 1)
00100 010 (X’22’: Mode 2)
Ultra DMA transfer mode X 01000 000 (X’40’: Mode 0)
01000 001 (X’41’: Mode 1)
01000 010 (X’42’: Mode 2)
01000 011 (X’43’: Mode 3)
01000 100 (X’44’: Mode 4)
01000 101 (X’45’: Mode 5)
*2) Advanced Power Management (APM)
The host writes the Sector Count register with the desired power management
level and executes this command with the Features register X’05’, and then
Advanced Power Management is enabled.
The drive automatically shifts to power saving mode up to the specified APM
level when the drive does not receive any commands for a specific time. The
sequence in which the power management level shifts is from Active Idle to Low
Power Idle to Standby. The Mode-2 level requires the longest shifting time,
depending on the APM level settings. The settings of the APM level revert to their
default values (Mode-1) when power-on or a hardware reset occurs for the drive
.
APM Level Sector Count Register
Mode 0 Active Idle → Low Power Idle
Mode 1 Active Idle → Low Power Idle
Mode 2 Active Idle → Low Power Idle → Standby
Reserve (State Keep)
C0h-FEh
80h-BFh
01h-7Fh
00h, FFh
Active Idle: The spindle motor rotates, and the head is loaded on
the most inner position on media.
Low Power Idle: The spindle motor rotates, and the head is unloaded.
Standby: The spindle motor stops, and the head is unloaded.