Radio Shack TRS-80 model III Owner's Manual page 9

OPERATION
Installation
First set
up
the
Computer
according
to the instructions
in
the
Model
III
Manual.
If
you have
a
one-
or
two-drive system,
installation
is
now
complete.
The
built-
in
drives
should be ready
for use.
If
you have
a three- or four-drive
system, you need
to
connect
the external
drives.
External
Disk Drives
The two
external drives are not interchangeable.
They have
different
Radio
Shack Catalog
Numbers
and
a
few
internal differences.
First
External
Drive Purchased
(Includes
Cable)
Second
External
Drive Purchased
System
Name
"Drive 2/3'
"Drive
2"
Catalog
Number
26-1164
26-1161
The
26-
1
164
drive
may
be used
as
Drive 2 or
3,
depending on
the
number
of
drives
in the
system,
In a
three-drive
system,
it
is
always Drive
2 (the
last
drive). In a four-drive
system,
it is
always Drive
3 (again, the
last drive).
The
26-1 161 drive
may
only be used
in
a four-drive system,
in
which
it
must
be
Drive
2.
1
Locate
the
flat
"ribbon"
cable
that
was included with
the
26-1 164
drive.
Notice
that
it
has a single
plug on one end, and
two
plugs clustered
at
the
other end.
See Figure
1
for
plug
labels.
2.
Connect
the solitary
"Computer"
plug
to
the
Disk Expansion Jack
on
the
bottom
rear
of
the
Computer. See Figure
2,
3.
Now
refer to
Figure
3.
Connect
the external drive(s) to the other
end of
the
cable, as follows:
3-
A.
If
you have one external drive (26-1
164);
Connect
it
to
the
"Drive
2"
plug near
the
middle
of the
ribbon
cable.
3-B.
If
you have two external drives (26-1 164 and
26-1
161):
Connect
the
26-1 164
to
the
"Drive
3"
plug on
the
end
of the cable.
Connect
the
26-1 161
to the
"Drive
2"
plug near the
middle of the cable.
4.
Plug the external drive(s) into
an
appropriate source of
ac
power.
Power
requirements are specified
on
the unit
and
in
the specifications
given
in this
manual.
You
are
now
ready
to start
the
Disk System.