Seagate 2531, 3240 manual Set Features command

28 Medalist 3240 and Medalist 2531 Product Manual, Rev. A

3.2.3Set 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 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 and 4 bytes of ECC. The acceptable values for the Features register are defined as follows:

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 (default)

0BH PIO mode 3

0CH PIO mode 4

10H Single-word DMA mode 0

11H Single-word DMA mode 1

12H Single-word DMA mode 2

20H Multiword DMA mode 0

21H Multiword DMA mode 1

22H Multiword DMA mode 2

44H Sixteen bytes of ECC apply on read long and write long commands

55H Disable read look-ahead (read cache) feature 66H Disable reverting to power-on defaults

82H Disable write cache

AAH Enable read look-ahead (read cache) feature (default)

BBH 4 bytes of ECC apply on read long and write long commands (default)

CCH Enable reverting to power-on defaults (default)

At power-on, or after a hardware reset, the default values of the features are as indicated above. A software reset also changes the features to default values unless a 66H command has been received.