Seagate ST32000641AS manual Set Features command values

4.3.2Set Features command

This command controls the implementation of various features that the drive supports. When the drive receives this com- mand, it sets BSY, checks the contents of the Features register, clears BSY and generates an interrupt. 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 7: Set Features command values

02H	Enable write cache (default).
03H	Set transfer mode (based on value in Sector Count register).
	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 (default)
	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
	45H	Ultra DMA mode 5
	46H	Ultra DMA mode 6
10H	Enable use of SATA features
55H	Disable read look-ahead (read cache) feature.
82H	Disable write cache
90H	Disable use of SATA features
AAH	Enable read look-ahead (read cache) feature (default).
F1H	Report full capacity available
Note.	At power-on, or after a hardware or software reset, the default values of the features are as indicated above.

Barracuda XT Series SATA Product Manual, Rev. C 27