3.17.11 DUAL PLATTER
This is a level which, when low, indicates the number of different platters contained in the
disk drive. A valid level will exist on the line whenever the particular disk drive is selected,
regardless
of
whether the particular drive is ready or not.
The following identifies the logic condition of this
line with regard to the type
of
disk drive
and number of platters.
Logic Level
High (false)
Low (true)
Type of Disk Drive Indicated
Single Removable Platter
Dual Platter -
One Fixed,
One Removable
No.
of
Platters
1
2
This line may
be
used by the controller or formatter to determine in advance the legal
number of storage surfaces available in a specific disk drive. This allows utilization of
different model disk drives on a common
I/O
bus.
3.17.12 DOUBLE TRACK
DRIVE
This is a level which indicates the number
of
usable cylinders that a particular
disk
unit
is
capable of accessing. A valid level
will exist on the line whenever the particular disk drive
is selected, regardless of whether the particular drive is ready or not.
Logic Level
High (false)
Low (true)
Type of Disk Drive Indicated
203
cylinders
406
cylinders
Corresponding tpi
100
200
This line may
be
used by the controller or formatter to determine in advance the range of
legal addresses that a specific disk drive can accommodate. This allows utilization of
different model disk drives on a common
110 bus.
3.17.13
SPECIAL INTERFACE SIGNAL
The special interface signal is used on both 100 and
200
tpi models.
On
100
tpi
disk drives,
the special interface signal line is used
to
provide either the
RUN
status
or
SAFE status of
the disk drive
to
the interface.
On
200
tpi disk drives, the special interface signal line is
dedicated to provide INTERNAL TEMPERATURE
GO
status to the interface. The
INTERNAL TEMPERATURE
GO
signal becomes a low-true logic level approximately 5
minutes after the disk drive indicates READY. This time delay is required to
allow the
internal temperature of the disk drive and cartridge
to
stabilize before commenCing a
WRITE or
READ
operation.
These signals are optional and must
be
specified at the time
of
order. It is important
to
note that only one
of
these signal options
can
be
provided
at
a time.
3-23
Il3OO
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