Set Features (Set Look Ahead Read) - Seagate Medalist ST3636A Product Manual

Chapter 7

Set Features (Set Look Ahead Read)

Page 60
Command Number: EF hex
Description: This command is used by the host to establish the following
parameters which affect the execution of certain drive features as shown below:
• 02 hex enables write cache.
• 82 hex disables write cache.
• AA hex enables Read Look Ahead.
• 55 hex disables Read Look Ahead.
• 03 Set Transfer Mode
Any other values in the Features (Write Precompensation) register will result
in the Error bit set in the Status Register and the ABRT (abort) bit set in the
Error Register. The default state on power up (Power On Reset) is determined
by the value of the Feature Word, which is factory set. The drive will retain the
settings through both soft and hard resets.
The Set Transfer Mode command set the current transfer mode according to the
content of the Sector Count Register. The valid Sector Count Register values
are shown in the table below:
Sector Count
Register Transfer Mode
00 hex Set default PIO transfer mode
01 hex
Disable IOCHRDY
08 hex Enable Mode 0 PIO with IOCHRDY enabled
09 hex
Enable Mode 1 PIO with IOCHRDY enabled
0A hex Enable Mode 2 PIO with IOCHRDY enabled
0B hex
Enable Mode 3 PIO with IOCHRDY enabled
0C hex Enable Mode 4 PIO with IOCHRDY enabled
20 hex Enable Multiword DMA Mode 0
21 hex Enable Multiword DMA Mode 1
22 hex Enable Multiword DMA Mode 2
One transfer mode subcommand may be issued for each SET FEATURES
Command.
Command Set
ST3636A/ST31082A/ST31276A