Quantum Instruments DLT 7000 - Manual (Page 68)

SCSI Description
3-4 Quantum DLT 7000 Tape System
Table 3–1 Implemented ANSI SCSI-2 Command (continued)
Command Code Class Description
SPACE 11h Mandatory Provides a selection of positioning
functions (both forward and backward)
that are determined by the code and
count.
TEST UNIT READY 00h Mandatory Provides a means to check if the logical
unit is ready.
VERIFY 2Fh Optional Requests the drive to verify the data
written to the medium.
WRITE 0Ah Mandatory Requests the drive to write the data
transferred from the initiator to the
medium.
WRITE BUFFER 3Bh Optional Used in conjunction with the READ
BUFFER command as a diagnostic for
testing target memory and the integrity
of the SCSI bus.
Used to update drive firmware from the
host via the SCSI bus.
WRITE FILEMARKS 10h Mandatory Requests that the target write the
specified number of filemarks or
setmarks to the current position on the
logical unit.
3.3 SIGNAL STATES
The following paragraphs describe signal values and SCSI ID bits.
3.3.1 Signal Values
All signal values are actively driven true (low voltage). Because the signal
drivers are OR-tied, the bus terminator’s bias circuitry pulls false when it is
released by the drivers at every SCSI device. If any device asserts a signal, (e.g.,
OR-tied signals), the signal is true. Table 3–2 lists the ANSI-specified and
defined signal sources. Any device can assert RST at any time.