ATAPI InterfaceChapter 5

Mode Select command

Bit

7

6

5

 

4

 

3

2

 

1

0

Byte

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

0

 

 

 

 

Operation code (15h)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

1

 

Reserved

 

 

1 (PF)

 

 

 

Reserved

 

 

 

 

 

 

 

 

 

 

 

 

 

2

 

 

 

 

Reserved

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

3

(MSB)

 

 

Parameter List Length

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

4

 

 

 

 

 

 

 

 

 

 

(LSB)

 

 

 

 

 

 

 

 

 

 

 

5

 

 

 

 

Reserved

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The Mode Select command provides a means to change device parameters. The PF (Page Format) bit is 1, since the Mode Pages are in SCSI-2 format. The only changeable parameters are Speed Selection (in the Mode Parameter Header), and certain fields in Mode Page 2Bh (MFM mode). The Parameter List Length field specifies the length in bytes of the Mode Select parameter list that are transferred to the device as data. A Parameter List Length of zero indicates that no data is transferred.

Mode Sense should be issued prior to Mode Select to determine the supported pages, page lengths, and other parameters.

The device terminates the Mode Select command with a Check Condition status, sets the Sense Key to Illegal Request, and sets the Additional Sense Code to Invalid Field in Parameter List for the following conditions:

If an attempt is made to change an unchangeable value in the Mode Select header, block descriptor, or any page.

If an attempt is made to send a page with a length not equal to the parameter length reported for that page by the Mode Sense command.

If an attempt is made to send a value for a parameter that is outside the range supported by the device.

STT8000A Product Manual

Page 47

Page 55
Image 55
Seagate STT8000A manual Mode Select command