Specifications

ATAPI For Streaming Tape QIC-157 Rev B

6. Streaming Tape Packet Commands

6.1. Packet Command Implementation Requirements

The first byte of all ATAPI Device Command Packets shall contain an operation code as defined in

this Specification. ATAPI Devices shall implement all commands with mandatory operation codes.

6.1.1. Reserved

Reserved bits, fields, bytes, and code values are set aside for future standardization. Their use and

interpretation may be specified by future extensions to this or other specifications. A reserved bit,

field, or byte shall be set to zero, or in accordance with a future extension to this specification. The

recipient shall not check reserved fields.

6.2. ATAPI Command Packet Description

An ATAPI command is communicated by sending a Command Packet to the ATAPI Device. For

several commands, the Command Packet is accompanied by a list of parameters sent upon receiving

an interrupt following the Command Packet being sent. See the specific commands for detailed

information.

The Command Packet always has an operation code as its first byte.

For all commands, if there is an invalid parameter in the Command Packet, then the ATAPI Device

shall abort the command without altering the medium.

Table 6-1 Typical Command Packet for Most Commands

Bit

Byte

7 6 5 4 3 2 1 0

0 Operation Code

1 Reserved

3 Reserved

4 Allocation Length, Parameter List Length, or Mode

5 (MSB) Parameter Pointer

6 (LSB)

7 (MSB) Allocation Length or Parameter List Length

8 (LSB)

9 Reserved

10 Reserved

11 Reserved