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SCSI Commands

5-68 Quantum DLT 4000 Tape Drive

MODE SELECT (6) / (10) Command (15h) / (55h) (continued)

Table 5–35 MODE SELECT Mode Parameter Block Descriptor - Field Descriptions

(continued)

Field Name Description

Block Length This field specifies the length, in bytes, of each logical block transferred over the

SCSI bus. A block length of 0 indicates that the length is variable (specified in the I/O

command). Any value other than 0 indicates the number of bytes per block to use

for READ, WRITE, and VERIFY commands that specify a “fixed” bit of 1 (i.e., fixed

block mode) which also causes the transfer length in the command descriptor

block to be defined as a block count. If fixed bit is not equal to 1, this field is

ignored.

5.9.1.3 Mode Page Descriptors

Following the MODE SELECT command’s Mode Parameter Block Descriptor are

the MODE SELECT pages, each of which sets a different device parameter. Each

mode page has a 2-byte header that identifies the page code and indicates the

number of bytes in that page.

Bit

Byte

7 6 5 4 3 2 1 0

0 PS (0) 0 Page Code

1 Additional Page Length

2 - n Page-Defined or Vendor Unique Parameter List

Figure 5–33 MODE SELECT Page Descriptor - Data Format

1 2 ... 163 164 165 166 167 168 169 170 171 172 173 ... 299 300

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Quantum DLT 4000 Manuel Page 168