Seagate BarraCuda Product Manual, Rev. A

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SATA Interface

5.3.2 Set 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 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 10 Set Features command

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.