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Fig. 2.6
24
[a]
[b)
---llii.im
Ic::::JI
./
f
'"
[d)
[e)
Two SCSI devices
on
the SCSI bus
Deux dlspositifs SCSI sur Ie bus SCSI
Zwel SCSI·Geriite auf dem SCSI·Bus
2-5 SeHing Up the SCSI Chain
The SCSI chain is the
electronic
data and control bus
that connects
two
or
more
SCSI
devices
. As mentioned
at
the
start
of this chapter, the SCSI chain can have
multiple
devices on the bus. Thus, the
name
"chain"
implies
the connection of these
devices
.
On any SCSI bus,
there
must be at
least
one SCSI
initiator
and one SCSI target. The LS-10E
scanner
is
always
a SCSI
target
device
. This is the standard
for
SCSI
scanners
.
Most
peripherals
connected to
computers
will
be SCSI
targets
.
Typically
, the
computer
will
be the SCSI
initiator
.
In certain cases,
there
can be
more
than one
initiator
on
a bus, and in fact
there
are
times
when a
computer
can
be an SCSI
target
device. These cases
are
rare
and
are
not covered in
this
manual.
In each case, the SCSI ID's of each
device
must
be
unique.
Two SCSI devices
In the
simplest
case,
only
two
devices
share
the SCSI
chain. These
are
referred to as the SCSI
initiator
and
the SCSI target. In
our
case,
the
SCSI
initiator
is the
computer
and the SCSI
target
is the scanner. This
simple
configuration is shown in
Figure
2.6.
[a]
Computer
SCSI
initiator
(internally
terminated)
[b] Scanner SCSI
target
[c] SCSI
terminator
[d] SCSI cable
In this case, both the SCSI
initiator
side
of
the
bus
and
the SCSI
target
side
of the
bus
have to be terminated,
as shown in Figure 2.6.