Specifications
;
Status
Bits
14=1
15=1
Status
Protect
fault
Drive seek
error
Description
An
unprotected controller opera-
tion
attempts
to read or write
in
a protected computer storage
area. If the error is
detected
while receiving control informa-
tion from storage, the operation
ends immediately. If the
error
is
detected while transferring
data
to or from storage, the operation
ends
at
the end of sector being
operated in.
The bit is cleared
by
any output
function.
The drive unit has
detected
that
the cylinder positioner has
moved beyond the legal limits of
the device (below cylinder zero
or above maximum cylinder) dur-
ing a load address, write, read,
compare, check word check, or
write address function.
The bit
function
status.
is cleared
by
any
that
sets
the busy
1738-853/854
Disk
Drive
Controller
Status
Bits
0=1
Status
Ready
96169450
A
Description
The selected unit is available and
ready to operate. The unit
becomes not ready for the
following reasons:
• The disk pack is not in the
drive unit.
• The disk drive motor is not
up
to operating speed
(2400
rpm).
• The read/write heads
are
not
in
operating position.
• A fault condition develops in
the selected unit
The ready status condition is
affected
by
the operating pro-
gram only
if
it
selects a non-
existing device or a device
that
is not ready. Normally, this
status
bit indicates
that
manual
intervention
is
required
at
the
selected drive unit.
Status
Bits
1=1
2=1
3=1
4=1
5=1
6=1
Status
Busy
Interrupt
On
cylinder
End-of-
operation
Alarm
No
compare
Description
The busy
status
indicates
that
the controller and/or the drive
unit is presently involved
in
the
performance of an operation.
Bit 1 is
set
by
the acceptance of
a load address, write, read, com-
pare, check word check, or write
address function.
The interrupt
status
indicates
that
a selected interrupt condi-
tion has occurred. The bit is
cleared by the acceptance of any
output function.
The on-cylinder
status
bit is
set
when the selected drive unit
positioner
is
on
cylinder. The
bit
is cleared if the drive unit is
presently positioning or
if
a seek
error is detected.
The end-of-operation
status
bit
is
set
whenever the controller
portion of an operation is com-
plete.
(The
busy
status
may
remain
set
if
the selected unit is
positioning.) This bit is cleared
by
any output function.
The alarm
status
indicates
that
one of the following abnormal
conditions occurred:
Not ready
Checkword error
Lost
data
Seek error
Address error
Defective track
Storage parity
error
Protect
fault
Bit 5 is cleared
by
any output
function. The not ready condi-
tion can be changed
by
selecting
another drive unit or
by
manual
intervention
at
the selected
drive unit.
Bit 6 being
set
indicates
that
the
data
received from computer
core storage does not compare
with data read from file storage
during a compare operation. The
bit is cleared
by
any output
function.
6-17