TAPE UNIT SCSI COMMANDS M2488 PRODUCT GUIDE
4-52 CG00000-011503 REV. A April 1997
same as the current parameters will not result in any change or the reporting of a Unit Attention to
other initiators. In any case, a Unit Attention condition due to mode parameters being changed will
not be generated for the initiator that performed the MODE SELECT command.
4-3.12.2 Mode Select Data
The Mode Select data to be sent by the initiator should be in the form of a four-byte header, fol-
lowed by a zero or an eight-byte block descriptor, followed by zero or more variable length pages.
The following table illustrates the format of the Mode Select parameter list:
Mode Select Parameter List Header:
Table 4-43. MODE SELECT Parameter List Format
BITS
BYTES 7 6 5 4 3 2 1 0
0 - n Mode Parameter Header (4 bytes). See Table 4-44.
0 - n Block Descriptor (0 or 8 bytes). See Table 4-47.
0 - n Pages. See Table 4-49.
Table 4-44. MODE SELECT Parameter Header
BITS
BYTES 7 6 5 4 3 2 1 0
0
Reserved
1
Reserved
2
0 Buffered Mode Speed
3
Block Descriptor Length (00h or 08h)
Table 4-45. MODE SELECT Parameter Header Field Description
BYTE BIT VALUE DESCRIPTION
2 0-3 The Speed field is ignored since the attached peripherals support only a
single speed.
2 4-6 0h-7h
The
Buffered Modes are described in Table 4-46.
3 0-7 A single block descriptor may be specified. The Block Descriptor Length
specifies the length in bytes (8) of the block descriptor, if included.
