Specifications

The following table illustrates a typical nondata command:
Step Process BSY DRQ INTRQ
1 Setup BSY=0 — —
2 Issue command BSY=0 — —
3 — BSY=1 — —
4 — BSY=0 — Assert
5 Read status BSY=0 — Negate
An important subset of the nondata commands are the power manage-
ment commands, all of which are optional within the ATA command
specification. These commands are treated in separate sections in the
text and tables that follow.
5.3 ATA interface command summaries
The following tables and text summarize the various ATA interface com-
mands. Most of these are identical to those described in dpANS ATA
Interface Revision 4.0. A few additional power management commands are
Seagate-specific. These can be divided into two groups: standard Seagate
power management commands and alternative Seagate power manage-
ment commands (the latter are used in some early Seagate drives).
All commands are issued to the drive in the following sequence:
1. The appropriate registers are loaded into the command block with the
necessary parameters.
2. The command code is written to the Command register.
3. The drive begins execution of the command.
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