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Installation
2-20.
TAPE
DRIVE
INSTALLATION
CHECK
Whenever
the
HP
9144A
Tape
Drive
is
switched
on
it
will
perform
a
series
of
selftests.
If
any
of
these
tests
fail,
the
drive's
FAULT
light will light
up and maintenance
should
be referred
to service
trained personnel.
Under
normal
circumstances
the
selftest
takes
about
7
seconds
(several
minutes
if
a
tape cartridge
is
fitted).
Further
information on
the
self test
routines
is
given
in
paragraph
2-52.
and
the nearest device
connected
to
it
and one
metre
of cable
between each
additional
device.
The
maximum
configuration
is
eight
devices
(excluding
the
CPU)
per
HP-IB
channel
or a
maximum
of
1
5
metres
or
1
5
equivalent
loads.
NOTE
The
maximum
number
of drives that
can
be
connected
to
a single
HP-IB
channel
is
host
dependent.
This
information
is
contained
in
the
appropriate
host
configuration
guide.
2-21.
INTERCONNECTION
INSTRUCTIONS
The
subsystem
is
connected
to
a
system using
1
-metre
HP-IB
cables,
model
number 10833A
(part
no.
8120-3445).
One
cable
is
used
to
connect
the
tape
drive's
HP-IB
connector
to
that
of
the
disc
drive
and
a
second
cable
connects the
subsystem
to
the
system
bus.
The
locations of
the
HP-IB
connectors
for the drives are
shown
in
figure
2-3.
The
major
HP-IB
considerations
concerning
the
subsystem
are
contained
in
the
following paragraphs
Although
the
HP
7914CT
subsystem
contains
an
HP
7914
Disc
Drive
and an
HP
9144A
Tape
Drive
in
one
cabinet,
it
should be noted
that
they
must
be considered
as
separate
devices
when
configuring
a
computer
system.
2-22.
HP-IB
CABLING.
The
Hewlett-Packard
Interface
Bus (HP-IB)
has
certain
rules
which
must
be
observed
for
successful installation
of the subsystem.
Cabling
is
limited
to
one metre
per
HP-IB
load.
Typically
the
Central
Processing
Unit (CPU)
is
7
equivalent
loads
and
the
drive
is
one
equivalent
load.
However,
in
the case of the
HP
7914CT,
the
disc
drive includes
one
additional
metre
of internal
cabling,
while the
disc
drive
and
tape drive
each
represent
one equivalent
load.
This causes the
complete
HP
7914CT
to
represent
two
equivalent
loads
(see
figure
2-4).
The
CPU
adheres
to
an
HP-IB
standard
which
allows seven
metres
of
HP-IB
cable
between
it
2-23.
HP-IB
DEVICE ADDRESS
The
HP-IB
address switches are located
on
the
rear panels of
each
drive
(see
figure
2-3).
The
HP-IB
address switches
permit
the
setting
of
one
of eight
unique
addresses.
The
address switches
can
be
set
with
any
pointed
tool.
Addresses
which
are generally
set
one
time, are
as
shown
in
table
2-1.
Table
2-1.
HP-IB
Addresses
Switch Settings
(msb)* 3
2
1
(
lsb)
0
0 0
0
0
1
0
10
0
11
10
0
10
1
110
111
HP-
IB
Address
0
1
2
3
4
5
6
7
*LSB
=
least significant bit
MSB
=
most significant bit
NOTE
When
setting
the
HP-IB
address
switches, disregard
any markings on
the switch
bodies.
Set
the switches
according
to
the
markings on
the rear
panel.
1
NOTE
Check
the
HP-IB
address
switches
and
ensure that
no two
devices
in
the
system have
the
same
address.
2-6
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