User's Guide

Page 76 DDS-4 SCSI Interface Manual, Rev. B

Parameter List—Block Descriptor Field Descriptions

The following table defines the fields in the Parameter List block descriptor.

Field

Name

Bytes

Description

Density

Code

0 The following values define this field:

Hex Code Meaning

00 Default format (DDS)

7F No-op

25 DDS-3

26 DDS-4

47 DAT 72

The drive will accept any of these density codes as valid when sending a Block

Descriptor. The density code does not dictate the format written on the media, the

drive detects the media type and writes the correct format for that media.

Selecting a Density Code value not listed above, or not supported by the drive,

will result in a Check Condition. The sense data is set to Invalid field in parameter

list.

Block

Length

5-7 If this field is nonzero, it indicates the length of the fixed-length block to be read or

written when the Fixed bit is set in a READ or WRITE command. (It is acceptable

to set the Fixed bit to 0.). The default is 512-byte blocks, which may be changed

at any time by the host with a MODE SELECT command.

If this field is zero, variable-length block mode is specified, and the Fixed bit in the

READ or WRITE command must be 0. The Block Length in a READ or WRITE

command may be set in a range from 1 to 16 MB (as specified in the READ

BLOCK LIMITS command.)

Mode Page Format

The following table shows the generic Mode Page format.

Byte

Bits

7 6 5 4 3 2 1 0

0 0 0 | Page Code

1 Page Length

Mode Parameters