3.16.13 START/STOP DISK
DRIVE
This is a level which, when low and the following conditions and restrictions are met,
allows the controller to start
and
stop the disk drive remotely.
The
function performed and
the resulting actions depend
on
the condition of the drive
at
the time this line goes low.
When the
START/STOP DISK
DRIVE
line is held at a high logic level,or Is not connected
the line has no effect on the operation of the disk drive.
Conditions and restrictions effecting this
line are:
(1)
This line
is
enabled at all times regardless of-the state
of
the UNIT SELECT lines.
Therefore, all disk drives on the common
I/O
line may respond
to
this
line.
(2) A true level on this line will cause the disk drive to commence a Start sequence
if
the drive is not already in a
Run
condition,
or
If the RUN/STOP
switch/indicator
is
not depressed and none of the following inhibiting conditions exist.
• The disk cartridge Is improperly inserted.
• Power is not applied.
• An internal emergency condition exists.
• The ACTIVATE EMERGENCY UNLOAD line Is being asserted.
When used for commanding a start operation, a pulse
of
not less than 260
~sec,
or
level change may be used.
(3)
A true level on this line
will
cause the disk drive to enter a Stop sequence
if
the
drive
Is in a
Run
condition
and
the RUN/STOP
switchlindicator
is not depressed.
The sequence will
be
completed
if
the WRITE ENABLE and ERASE ENABLE inter-
face signals are high.
When used for commanding a
Stop operation, a pulse
of
not less than 60 sec,
or
a level change, may
be
used.
(4) Since the START/STOP DISK
DRIVE
line performs the same function as the RUN/
STOP
switch I indicator, priority
is
by first actuation.
If
the START/STOP DISK
DRIVE
line is actuated continuously, the RUN/STOP
switch/indicator is locked out during this period; conversely, If the RUN/STOP
switch/indicator
Is depressed and held, the START/STOP DISK
DRIVE
line
is
locked out during this period.
3.17
INTERFACE
OUTPUTS
(DISK
DRIVE
TO
CONTROLLER)
All signal names are chosen to correspond to the logical true condition. All interface lines
are low-true at the interface with the low condition considered to
be
Ov,
and the high
condition considered
to
be
+3v.
3.17.1
READY
This Is a level which, when low, indicates that the disk unit is in a Ready condition. The
Ready condition is defined as that condition which exists when the
following
requirements
are
met.
(1)
All power is applied
and
correct.
(2)
A cartridge is correctly Inserted.
(3)
The disk is rotating at the correct speed.
(4)
The heads are loaded.
(5)
No equipment faults
are
detected.
(6)
The logiC
is
prepared to recognize commands.
3-18
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