Fixed
Disk
Platter
Figure
1-3.
Model 2280/2280N Disk
Unit Read/Write
Heads
1.2 THE
DISK PROCESSING UNIT
The Disk Processing
Unit, included in
the price of all
2280 disk
drives,
is an intelligent controller/processor enabling two Model
2280/2280N
drives
to
operate
quickly and efficiently. When attached
to a standard
2200 disk
controller,
this self-contained unit controls
data transfer
between
the disk
platters and the 2200 system CPU. The DPU can thereby handle
multi-sector
data
buffering, and control read/write, format,
copy and verify
operations.
The
DPU also performs
extensive error checking
and correction.
By
off-loading responsibility
for
the above tasks
from the
CPU to the
DPU,
overall system performcince has been significantly improved.
For
example,
the
COPY function without the
DPU requires
approximately five
minutes.
With
the
DPU, this time has been reduced to
two
minutes. Likewise,
the DPU
allows
a
VERIFY operation
to
be
completed in
approximately 25
seconds for
a 13.4
megabyte
disk.
The
2280/2280N disk drive unit can also
be
given
multiplexing
capability
with the addition of an
optional
Model 2280MUX. Using
a "star"
type
configuration, up to
three VP or
MVP
CPU's
an be individually connected
to a
2280
DPU. Each CPU may
be
separated by a
maximum
of 1000
feet
(304.8
m)
from
the 2280 DPU,
thus
allowing for
multiple
MVP's or VP's
to share over
160
megabytes
of random access storage.
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