ST1.3 Series Product Manual, Rev. C 31

4.1.3 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 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 10: Features register values
Feature Description
02HEnable Write Cache.
03H
Used for Set transfer mode Command.
Sector Count register values:
00HSet PIO mode to default (PIO mode 2).
01HSet PIO mode to default and disable IORDY (PIO mode 2).
08HPIO mode 0
09HPIO mode 1
0AHPIO mode 2
0BHPIO mode 3
0CHPIO mode 4
20HMultiword DMA mode 0
21HMultiword DMA mode 1
22HMultiword DMA mode 2
40HUltra DMA mode 0
41HUltra DMA mode 1
42HUltra DMA mode 2
43HUltra DMA mode 3
44HUltra DMA mode 4
05HEnable advanced power management
55HDisable read look-ahead (read cache) feature.
66HDisable Power On Reset (POR) establishment of defaults at Soft Reset.
82HDisable write cache.
85HDisable Advanced Power Management
AAHEnable read look-ahead (read cache) feature.
CCHEnable Power On Reset (POR) establishment of defaults at soft reset