Operating instructions

2-8
SCSI REFERENCE PRELIMINARY 1012975
CHAPTER 2—OVERVIEW OF THE AUTOLOADER AS A SCSI DEVICE
2.4.2 SCSI COMMAND FORMAT
The autoloader uses six-, ten-, and twelve-byte commands, whose formats are
described in the SCSI-3 standards (SPC-2, SMC, SAM-2, SPI-2). Any command
descriptor block (CDB) fields that are specific to the autoloader for a given
command are described in the command chapter. This section describes the
CDB fields that are common for every command.
Note: Any errors caused by illegal parameters in a CDB or parameter list for a
particular command are listed at the end of the command chapter. Errors
of this type return a sense key of Illegal Request (5h).
 The word Reserved or RSVD has one of the following meanings when used
in a SCSI command field definition:
 The field is defined as reserved by the ANSI Small Computer System
Interface (SCSI) standard. The autoloader checks these fields for a value
of 0. If zeros are not present, the autoloader returns Check Condition
status with the sense key set to Illegal Request (5h).
 The field description, “This field not supported by the autoloader,”
indicates that the field is supported by the SCSI-3 standards, but has not
been defined in the Exabyte implementation of the command. These
fields are reserved for future enhancements. The autoloader ignores
these fields and does not check for illegal values.
 The vendor unique portion of the Control byte (as indicated in the SCSI
standard) is defined for each specific command, if used. The autoloader does
not support linked commands or recognize the Flag bit.
 Fields containing only one bit are usually referred to as the name bit instead
of the name field.
 Numbers that are not immediately followed by lower-case b or h are decimal
values.
 Numbers immediately followed by lower-case b (nnb) are binary values.
TEST UNIT READY (6 bytes) 00h Informs the initiator whether it is ready to accept all
other commands.
Chapter 24
WRITE BUFFER (10 bytes) 3Bh Writes new microcode received from the initiator
into its flash EEPROM. The new microcode must be
sent in sections through multiple WRITE BUFFER
commands.
Chapter 25
Table 2-3 SCSI command set supported by the autoloader (continued)
When you issue this
command …
OP
Code
The autoloader does this … Discussed
in...