Specifications

ATAPI For Streaming Tape QIC-157 Rev B

6.8.7. MODE SELECT Command

The MODE SELECT command provides a means to specify medium or Device parameters. Devices

that implement the MODE SELECT command shall also implement the MODE SENSE command.

MODE SENSE should be issued prior to MODE SELECT to determine supported pages, page

lengths, and other parameters.

Table 6-29 Mode Select Command

Bit

Byte

7 6 5 4 3 2 1 0

0 Operation code (15h)

1 Reserved 1 (PF) Reserved 0 (SP)

2 Reserved

3 (MSB) Parameter List Length

4 (LSB)

5 Reserved

6 Reserved

7 Reserved

8 Reserved

9 Reserved

10 Reserved

11 Reserved

The Parameter List Length field specifies the length in bytes of the MODE SELECT parameter list

that shall be transferred to the Device as data. A Parameter List Length of zero indicates that no data

shall be transferred. This condition shall not be considered as an error. A Parameter List Length that

results in the truncation of any descriptor, header or page of parameters shall cause the Device to

terminate the command with “Check Condition” status. The Sense Key shall be set to ILLEGAL

REQUEST, and the Additional Sense Code shall be set to PARAMETER LIST LENGTH ERROR.

[Implementor's Note: In some situations where there is a conflict between the information in the command descriptor

block and the information in the parameter list, one of several additional sense codes may apply. As a guide, INVALID

FIELD IN COMMAND PACKET or PARAMETER LIST LENGTH ERROR should be used if the error is detected prior

to any operations that alter the mode parameters. INVALID FIELD IN PARAMETER LIST should be used if the mode

parameters have been altered.]

The Device shall terminate the MODE SELECT command with “Check Condition” status, set the

Sense Key to ILLEGAL REQUEST and set the Additional Sense Code to INVALID FIELD IN

PARAMETER LIST for the following conditions:

1. If an attempt to send an unsupported value in the MODE SELECT header, block descriptor, or any

page header.

2. If an attempt to send a page with a length not equal to the parameter length reported for that page

by the MODE SENSE command.

3. If an attempt to send a value for a parameter that is outside the range supported by the Device and

rounding is not implemented for that parameter.