Sony AIT-SDX460, Руководство по техническим характеристикам продукции

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5. ATA/ATAPI Interface
SONY AIT-1 Turbo drive SDX-460V series Ver.1.0 5-1
5. ATA/ATAPI Interface
5.1. Introduction
The SONY SDX-460V ATAPI TAPE DRIVE uses the ATA Packet Interface (ATAPI) to connect to the host system.
ATAPI is an industry standard interface, approved by the American National Standards Institute (ANSI). It is
recommended that this document be used along with the ANSI standard document. The ANSI specification
defines the interface in general while this document describes the specific implementation for this unit. The
ATA/ATAPI documents, listed in detail in section 1.2, offer the information required to integrate this unit with
ATAPI compatible computer systems.
The Introduction provides general, high-level information. For the hardware description and the installation
requirements, see section 2.
5.2. Overview of Interface
The ATAPI implementation provides the unit with a standard set of features and functions. These include:
•
Support for 2 devices (master and slave)
•
Registers for passing command and control information
•
Device addressing considerations
In traditional controller operation, only the selected device receives commands from the host following selection.
For ATAPI devices, when a register is written, the value is written to the register of both devices. The host
discriminates between the two by using the DEV bit in the Device/Head register. When the DEV bit is cleared to
zero, Device 0 is selected. When the DEV bit is set to one, Device 1 is selected. When two devices are connected
to the cable, one shall be set as Device 0 and the other as Device 1
The devices using this interface shall be programmed by the host computer to perform commands and return
status to the host at command completion. Commands may be delivered in two forms. ATAPI devices use the
PACKET Command feature set which utilizes packet delivered commands as well as some register delivered
commands. Register delivered commands and command parameters are delivered by writing the device
Command Block registers.
When two devices are connected on the cable, commands are written in parallel to both devices, and for all except
the EXECUTE DEVICE DIAGNOSTIC command, only the selected device executes the command. Both devices
shall execute an EXECUTE DEVICE DIAGNOSTIC command regardless of which device is selected, and Device
1 shall post status to Device 0 via PDIAG-.
When the Device Control register is written, both devices respond to the write regardless of which device is
selected.
Data is transferred in parallel either to or from host memory to the device’s buffer under the direction of commands
previously transferred from the host. The device performs all of the operations necessary to properly write data to,
or read data from, the media. Data read from the media is stored in the device’s buffer pending transfer to the host
memory and data is transferred from the host memory to the device’s buffer to be written to the media.