Specifications

1.0 Introduction
This manual describes Seagate Technology’s implementation of the AT
Attachment (ATA) interface, an intelligent hard disc drive interface for
use in personal computer systems. This manual includes supported ATA
interface commands, command execution, translation methodology,
caching, power management, signal conventions, line specifications,
and interpretations of error conditions. These interface descriptions are
based on the draft proposed American National Standard (dpANS) ATA
Interface Revision 4.0. For information on a particular Seagate ATA
interface drive (including any drive-unique features not listed in this
document), refer to the product manual for the specific drive.
1.1 Advantages of the ATA interface
The ATA interface is a natural extension of the ISA system bus. Most of
the signals and circuitry necessary for the interface are already present
in the host system. The interface is easily implemented into the design
of an ISA or EISA system with little or no extension required in the system
software. It is for this reason that the ATA interface standard has gained
such wide acceptance in the personal computer industry.
The ATA interface is designated as a logic-level interface, and responds
to high-level commands from the host. The drive itself is an intelligent
device with an embedded controller that interprets and executes the
commands sent from the host. After command execution, the drive
reports information on successful command completion, any error con-
ditions and all parameters appropriate to drive status queries.
Features incorporated in some or all of Seagate’s ATA interface drives
include:
• Translation capabilities for emulating head, cylinder, and sector ge-
ometries that do not match the native geometry of the drive
• Defect management, which provides automatic reallocation of bad
sectors
• Drive caching that significantly improves drive performance, espe-
cially in DOS environments
• Multisegmented adaptive caching, allowing the drive to adapt the
caching algorithm based on the profile of read/write requests
• Power management capabilities, which are necessary for use in
portable computers and energy-efficient desktop systems. Power
management features can be set through the system software, allow-
ATA Interface Reference Manual, Rev. C 1