Seagate ST94811A, ST94011A, ST92811A, ST92011A manual Set Features command, Features register values

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 8:		Features register 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
05H	Enable advanced power management
55H	Disable read look-ahead (read cache) feature.
82H	Disable write cache.
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 indi- cated above.

26 Momentus 5400.1 Product Manual, Rev. F