Seagate ST680712DEG manual Set Features command, Features register values, Feature Description

4.1.3Set Features command

This command controls the implementation of various features that the drive supports. When the drive receives this command, it sets BSY, checks the contents of the Features register, clears BSY and generates an inter- rupt. If the value in the register does not represent a feature that the drive supports, the command is aborted. Power-on default has the read look-ahead and write caching features enabled. The acceptable values for the Features register are defined as follows:

Table 10:	Features register values
Feature	Description
02H	Enable Write Cache.
03H	Used for Set transfer mode Command.
	Sector Count register values:
	00H	Set PIO mode to default (PIO mode 2).
	01H	Set PIO mode to default and disable IORDY (PIO mode 2).
	08H	PIO mode 0
	09H	PIO mode 1
	0AH	PIO mode 2
	0BH	PIO mode 3
	0CH	PIO mode 4
	20H	Multiword DMA mode 0
	21H	Multiword DMA mode 1
	22H	Multiword DMA mode 2
	40H	Ultra DMA mode 0
	41H	Ultra DMA mode 1
	42H	Ultra DMA mode 2
	43H	Ultra DMA mode 3
	44H	Ultra DMA mode 4
05H	Enable advanced power management
55H	Disable read look-ahead (read cache) feature.
66H	Disable Power On Reset (POR) establishment of defaults at Soft Reset.
82H	Disable write cache.
85H	Disable Advanced Power Management
AAH	Enable read look-ahead (read cache) feature.
CCH	Enable Power On Reset (POR) establishment of defaults at soft reset

ST1.3 Series Product Manual, Rev. C 31