Specifications

ATAPI For Streaming Tape QIC-157 Rev B

the Device asserts INTRQ before testing DRQ following the transfer of the last data word in a

command or data packet.

See section 4.1.7.1 General Configuration Word (0), on page 25 for additional DRQ and other

timing related information.

2.14. BIOS and ATAPI Driver Compatibility

This section discusses the IDE features and functions that shall be provided by the ATA Drive to

allow the BIOS and Driver to be content.

2.14.1. Reset Master/Slave Diagnostics Sequence

A Reset Master/Slave Diagnostics Sequence with a “Good” Status shall be provided or the BIOS

will not continue. When the Streaming Tape is the slave Device, and it does not respond after the

Reset or Diagnostic Commands, the Master Device will return an Error Condition to the Host and

all will die.

2.14.2. SRST Initialization Sequence

The SRST bit in the ATAPI Device Control Register (See Figure 3-7 ATAPI Device Control

Instead the ATAPI Device Driver shall reset the ATAPI Device utilizing the ATAPI Soft Reset

command (see 3.2 ATAPI Soft Reset Command and Protocol on page 17). Resetting the ATAPI

Device using the ATA SRST would also reset any ATA hard Drive attached, and if there are

separate Drivers for an IDE and an ATAPI Device, each Driver would be resetting the others

peripheral without the other Driver being aware of the reset.

After Receipt of an ATAPI Packet Command there are several differences from the ATA

Specification:

A value other than 00h in the status register prior to the receipt of the first ATAPI Command Packet

from the Host may cause ATAPI Devices to be incorrectly identified by pre-ATAPI Host BIOS as

an ATA-compatible disk Drive.

Initializing the task file upon receipt of an SRST should work since only immediate commands with

a delayed process will be executing when an ATA disk Driver issues an SRST. To prevent

interruption of the delayed process that have not finished executing, the function of the DSC bit (i.e.

command complete) shall be restored (along with DRDY being set) by issuing an ATAPI Identify

or Packet command. On a warm boot the BIOS and/or Drivers will see a status of 00h.

The signature placed in the task file following an SRST shall remain until the ATAPI Device

receives its first ATAPI command, i.e., the ATAPI Device will look NOT READY (DRDY=0).

This will not affect the ATAPI Device Drivers ability to send ATAPI commands to the ATAPI

Device since it is not required to wait for DRDY=1. However, it will prevent ATA-compatible

Drivers, such as those performing power management, from sending commands to an ATAPI

Device until the ATAPI Device has received its first ATAPI command: ATAPI Packet Command,

ATAPI Identify Device.

ATAPI Drivers wishing to use ATA power management commands must poll DRDY and, if it is

not set, they must also look at the Cylinder registers for the ATAPI signature. If the signature is