Service manual
4-
8
1'--
DOUBLE-DENSITY
DISK
CONTROLLER
DISK CONTROLLER CHECKOUT
The
Disk Controller Checkout is
used
to verify
the
operation of
the
Z-89-37
disk
control-
ler circuit board.
This
diagnostic program
turns
on
the
disk
drive motors,
loads
the
disk
drive read/write heads as a
program
would
if
it
were trying
to
read
from or
write
to
the
disk,
and
then
tries to
position
and
reposition
the
read/write head.
If
the
program
can
successfully complete all
these
tests, it
will
print
a message
which
indicates
that
the
controller works properly.
If
the
program
cannot
successfully
complete
any
test,
it
will
print
an
error message
which
tells you
how
to
correct
the
problem.
The
Disk Controller Checkout diagnostic will refer to various drive numbers. These
numbers
are
the
drive
hardware
unit
numbers,
and
they
range
from 0 (zero)
through
2.
Pay close attention to
which
number
the
program
associates
with
a drive as
it
activates it.
This
"drive
hardware
unit
number"
will
be referred
to
frequently
throughout
these
diagnostics.
To
run
the
Disk Controller Checkout, select diagnostic
program's
main
menu
option
2.
The
system will print:
Detailed
Controller
Checkout.
This
program
attempts
to
verify
the
operation
of
the
Z-37
disk
controller
board.
Please
answer
the
following
questions
with
'Y'
For
YES
and
'N'
for
NO,
by
looking
at
your
Disk
Drivers
and
verifying
proper
operation.
Are
All
Drive
Motors
Turning?
To respond,
open
the
doors of
the
drives
on
your
Z-37(s).
On
the
right-hand
side
of
the
drive, about
two
inches
back
from
the
drive door, is a metal cylinder
which
measures
about
an
inch
in
diameter. Make
sure
this
cylinder
is
turning
in
each
ofthe
drives
in
your
Z-37(s).
It
does
not
matter
whether
this
cylinder
is
turning
in
any
drives
connected
to
an
H-88-1 hard-sectored controller.
If
all
the
cylinders are
turning,
respond
Y.
Otherwise,respondN
and
turn
toPage4-13
for
an
explanation
of
the
message you receive.
If
you have
responded
Y to
the
preceding
question,
the
program
will
print:
Selecting
Drive
Zero.
If
this
is
a
non-existent
drive
for
your
system,
Answer
'Y'
to
the
following
question.
Is
Drive
Select
Light
On
and
Head
Loaded?
Note
that
this "Drive Zero" is
the
drive
which
you normally
use
to boot
up.