Samsung 3.5" hard disk drives, spinpoint v40 manual Set Features EFh, Mode

DISK DRIVE OPERATION

6.4.19 Set Features (EFh)

This command is used by the host to establish the following parameters, which affect the execution of certain drive features as shown in Table 6-8.

	Table 6-8Set Feature Register Definitions
Code	Description
02h	Enable Write Cache
03h	Set transfer mode based on value in Sector Count register
33h	Disable Retry
42h	Enable Automatic Acoustic management feature set.
44h	Entire bytes of ECC apply on Read Long/Write Long commands
55h	Disable read look-ahead feature
66h	Disable reverting to power on defaults
77h	Disable ECC
82h	Disable Write Cache
88h	Enable ECC
99h	Enable Retries
AAh	Enable read look-ahead feature
BBh	4 bytes of ECC apply on Read Long/Write Long commands
C2h	Disable Automatic Acoustic management feature set.
CCh	Enable reverting to power on defaults

When the drive receives this command, it sets BSY, checks the contents of the Feature register, clears BSY, and generates an interrupt. If the value in the Feature register is not supported or is invalid, the drive posts an Aborted Command error. Refer to section 6.6.3 for the protocol.

A host can choose the transfer mechanism by Set Transfer Mode and specifying a value in the Sector Count register. The upper 5 bits define the type of transfer, and the low order 3 bits encode the mode value. Refer to Table 6-9.

Table 6-9Transfer mode values

MODE	Bits(7:3)	Bits(2:0)
PIO default mode	00000	000
PIO default mode, disable IORDY	00000	001
PIO flow control transfer mode	00001	mode
Multiword DMA mode	00100	mode
Ultra DMA mode	01000	mode

mode = transfer mode number

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