3.17.2
BUSY
SEEKING
(4
LINES)
This group
of
four lines provides signals indicating (on separate lines) that the drive is
busy seeking a new
cylinder position. These lines do not require that the drive be
selected in order
to
enable these signals; therefore, the current status is always indicated.
When
the Unit Number Serector Switch is set
to
a given number, the corresponding BUSY
SEEKING line
number will
be
indicated.
When a
BUSY SEEKING line Is low,
It
indicates that the drive is executing or processing
the previous operation commanded by
CYLINDER
ADDRESS
STROBE.
The
appropriate line will go low within 1.0
,",sec
of the leading edge
of
any strobe that is
recognized.
If the operation commanded does not result in positioner motion (illegal address
or
address same as current position) the line will
go
high within 2.0
fJ.sec
of
the trailing edge
of the strobe.
If the operation commanded results in a normal cylinder seek operation, the line will
remain low for the duration
of
the cylinder
seek
time (defined as the time from the trailing
edge
of
strobe to the trailing edge
of
BUSY SEEKING). At the end
of
the seek operation,
the line will go high.
If the operation commanded results in a restore operation, the line will remain true for a
maximum of 3 seconds (specified time is from the
trailing edge of strobe to the trailing
edge
of
BUSY
SEEKING). At the
end
of the restore operation the line will go high.
The readiness of the disk drive to perform a read/write operation is inferred by a high level
on
the
BUSY
SEEKING line; however, the unit must also
be
selected
and
ready
to
execute
read
I write operation.
3.17.3
SECTOR
PULSE.
The
pulses on this line may
be
used for sectoring a disk
if
the address marker method is
nato
utilized. These pulses occur at regular intervals during each revolution
of
the disk.
These pulses, in essence, divide the disk (surface) into
N equal segments, where N is the
number of pulses.
In
disk drive models utilizing the
544O-type
cartridge, the
SECTOR
PULSE
line provides
electronically generated pulses
of
predetermined number; the number is specified at the
time of order. This may
be readily changed
in
the field
by
plugging in a different
programming-array plug. This plug configures tne disk drive to generate a specific number
of sector pulses.
For disk drives incorporating a fixed disk
as
well
as
a
5440
removable disk, the number of
sector pulses for the fixed disk are also determined
by
a plug-In array.
In
disk drive models utilizing the 231S·type cartridge, the
SECTOR
PULSE
line provides
pulses derived from the sector
rinOg
on
the cartridge.
One
pulse for each sector slot is
issued (this applies
only to the removable disk).
In
some applications
it
may
be
deSirable
to utilize electronically generated sector pulses in lieu
of
sectoring by the 2315-type
cartridge sector ring. This
can
be
configured by plugging in the appropriate
programming-array
plug. The sector pulses for the removable disk will then be similar to
the arrangement described previously for the 5440-type cartridge.
3-19
To Next Page
Loading...