Electrical computers and digital data processing systems: input/ – Input/output data processing – Data transfer specifying
Reexamination Certificate
2000-02-14
2001-10-30
Pan, Daniel H. (Department: 2783)
Electrical computers and digital data processing systems: input/
Input/output data processing
Data transfer specifying
C710S061000, C710S033000, C711S111000, C711S112000, C369S047360
Reexamination Certificate
active
06311236
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a magnetic disc apparatus for use in an information processing apparatus such as a computer, and more particularly, to a magnetic disc apparatus including an LSI (large-scale integrated circuit) for a magnetic disc apparatus which is capable of performing high speed read and write operations by parallelly reading and writing data from and to the magnetic disc apparatus, as well as effectively utilizing recording surfaces of magnetic discs by selecting a spare track or a spare sector in place of a defective track or a defective sector on the magnetic disc.
A conventional magnetic disc apparatus known as a parallel read and write type is described in Japanese Patent Application Laid-Open Publication No. 61-145767, which divides data belonging to a single sector on a data recording surface to simultaneously record the divided data in parallel, and simultaneously reads data recorded on respective data recording surfaces in parallel and synthesizes the same to data in sector units to thereby increase a data transfer speed.
As a counterpart of the above-mentioned parallel read and write type magnetic disc apparatus, there is a serial read and write type magnetic disc apparatus whose internal structure is shown in a block diagram of FIG.
17
.
In
FIG. 17
, reference numeral
1
designates a host computer,
2
a magnetic disc apparatus,
3
a host interface control unit,
4
a buffer memory,
5
a disc control unit,
6
a microprocessor,
8
a recording and reproducing unit,
9
an encoder/decoder circuit,
11
a head circuit,
14
a parallel interface.
When a parallel data of, for example, eight bits is supplied from the host computer
1
through the parallel interface
14
, the parallel data is delivered in the magnetic disc apparatus
2
from the host interface control unit
3
to the disc control unit
5
where the parallel data is parallel-to-serial converted. The serially converted data is written one bit by one bit on a recording surface of a magnetic disc, not shown, through the encoder/decoder circuit
9
by the head circuit
11
as serial data. On the other hand, data serially read one bit by one bit is delivered through the encoder/decoder circuit
9
to the disc control unit
5
. The disc control unit
5
converts the serial data to a parallel form, and this parallel data is transferred to the host computer
1
through the host interface control unit
3
and the parallel interface
14
.
FIG. 18
is a block diagram showing the disc control unit
5
as shown in
FIG. 17
in detail.
In
FIG. 18
, reference numeral
24
designates a MPU (microprocessor unit) interface unit,
25
a host interface control unit,
7
b
a parallel-to-serial conversion unit,
27
a drive control unit, and
28
an ECC unit for detecting and correcting data errors. It will be appreciated that a serial data transmission path is established by data transmission paths from the parallel-to-serial conversion unit
7
b
to the drive control unit
27
and the ECC unit, and from the drive control unit
27
to the encoder/decoder unit
9
and thereafter.
FIG. 19
is a block diagram showing an internal structure of a conventional parallel read and write type magnetic disc apparatus. A magnetic disc apparatus
2
shown in this drawing comprises a plurality of disc-shaped recording surfaces constituting a single cylinder and read and write heads respectively corresponding to the respective recording surfaces, as shown in FIG.
20
. When a disc control unit
5
receives m-bit parallel data from a host computer
1
, the m-bit parallel data is output from disc control unit
5
as m-bit serial data on a single path (see FIG.
18
). The m-bit serial data on a single path is converted into (m/2)-bit serial data on two paths to form two data trains by a single serial path to plural serial path conversion unit
7
. The two data trains outputted as the results are encoded by the encoder/decoder circuit
9
, and then they are assigned to two heads selected from a plurality of heads (by a head circuit
11
). These two data trains are parallelly written on two disc-shaped recording surfaces corresponding to the selected two heads. On the other hand, when data is read from recording surfaces, two data trains are parallelly read from two disc-shaped recording surfaces corresponding to two heads. The read data trains are decoded converted from (m/2)-bit serial data on two paths to m-bit serial data on a single path, and then integrated to m-bit parallel data by the disc control unit
5
and outputted to the host computer
1
.
FIG. 20
is a lateral view showing a structure of magnetic discs and heads in the magnetic disc apparatus in FIG.
19
.
In this drawing, five recording discs
51
are concentrically supported to constitute a cylinder, wherein the upper surface and the lower surface of each disc respectively constitute recording surfaces. Specifically, the upper surface and the lower surface of the respective five recording discs
51
are utilized as recording surfaces, so that there is a total of ten recording surfaces which correspond to a servo surface
52
and first to ninth data recording surfaces
53
-
1
to
53
-
9
. Also, ten heads H are provided for the respective recording surfaces so as to be associated with one another.
FIG. 21
is a block diagram showing a circuit arrangement of the recording and reproducing unit
8
of the conventional magnetic disc apparatus shown in
FIG. 19
in a data write operation.
In
FIG. 21
, the encoder/decoder unit
9
is shown as comprising n encoder circuits
16
while the head circuit
11
is shown as comprising n head amplifiers
17
and n heads
18
when writing data. If 2-bit parallel data is to be written, n is naturally 2. Reference numeral
15
designates a write clock generating circuit,
19
an NRZ (Non-Return to Zero) signal.
FIG. 22
is a block diagram showing a circuit arrangement of the recording and reproducing unit
8
of the conventional disc apparatus shown in
FIG. 19
when data is read.
In
FIG. 22
, the encoder/decoder unit
9
is shown as comprising n decoder circuits
22
and n waveform shaper circuits
23
, and the head circuit is shown as comprising n head amplifiers
17
and n heads
18
when, upon reading data. However, as mentioned above, if 2-bit parallel data is to be read, n is naturally 2. Reference numeral
21
designates a phase synchronizing circuit.
The above-mentioned prior art is useful in achieving a high speed data transfer by performing parallel write and read operations. However, it does not consider a combination of data recording surfaces on which data divided from parallel data are to be stored, which results in always providing fixed combinations of the recording surfaces for a simultaneous read or write operation. For this reason, the prior art implies problems in a decrease of a storage capacity due to defective recording surfaces, which is remarkably important in a parallel read and write operation, and a deterioration in a data transfer speed caused by reassignment of spare tracks and spare sectors in place of defective tracks and defective sectors.
For example, as shown in the previously explained
FIG. 20
, in the magnetic disc apparatus of a dedicated servo system or a servo system using a servo surface employing five recording discs
51
, assume that a two-bit parallel recording is performed where parallel data transferred from the host computer
1
is divided into two data trains, and a write or read operation of the two data trains is simultaneously carried out by the use of two data recording surfaces.
As shown in
FIG. 20
, nine out of ten recording surfaces are used as data recording surfaces (data recording surfaces
53
-
1
to
53
-
9
). Therefore, if two surfaces are fixedly combined to be one unit for the two-bit parallel recording, one data recording surface inevitably remains unused and cannot be utilized for reading and writing data.
If the recording surfaces for the two-bit parallel recording are made by combinations of the data recording surfaces
53
-
Hirose Tsuneo
Karasawa Noriyuki
Kawamura Satoshi
Kubo Mitsuru
Oeda Takashi
Antonelli Terry Stout & Kraus LLP
Hitachi , Ltd.
Pan Daniel H.
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