Error detection/correction and fault detection/recovery – Pulse or data error handling – Digital data error correction
Reexamination Certificate
1998-08-05
2001-04-24
Baker, Stephen M. (Department: 2133)
Error detection/correction and fault detection/recovery
Pulse or data error handling
Digital data error correction
Reexamination Certificate
active
06223321
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an error correcting process in a data reading operation of a recording/reproduction device such as a floppy disk drive.
2. Description of the Related Art
Data stored in a floppy disk serving as a storage medium may not be correctly read due to scratches in the floppy disk or a reading error in a device. For this reason, in data reading from the storage medium, an error correcting process for data is required.
In order to improve the reliability of the data stored in the floppy disk, the error correction in data reading has two or more stages.
A conventional floppy disk drive will be described below with reference to
FIGS. 3 and 4
.
FIG. 3
is a block diagram showing a conventional floppy disk drive in which data is read from a floppy disk
101
, error correction for the read data is performed, and the data subjected to the error correction is output to a host computer
110
.
Here, for example, data correction of the first stage is defined as C1 correction, and data correction of the second stage is defined as C2 correction. For example, the C1 correction and the C2 correction will be described below on the assumption that “Reed-Solomon code” is used in each of the C1 correction and the C2 correction.
FIG. 4
shows a data storage format on a floppy disk. Referring to
FIG. 4
, for example, “data 1” to “data 80” are blocks (to be referred to as sectors hereinafter) of original data which are stored. Each block has a data capacity of 256 bytes.
“C1 correction data” paired with each of “data 1” to “data 80” is redundant data (to be referred to as inspection data hereinafter) for performing inspection for an error of original 256-byte data.
“C2 correction data” is inspection data for performing error correction to each of the sectors of “data 1” to “data 80” in units of bytes. More specifically, “C2 correction data” is inspection data for performing error correction corresponding to regions A1 to A256 obtained by dividing information data in each of the sectors of “data 1” to “data 80” in units of bytes.
In addition, “C1 correction data” also exists in “C2 correction data”, and error correction form “C2 correction data” is performed in C1 correction.
For example, in
FIG. 3
, a control circuit
102
causes a reader
101
to read data from a floppy disk
101
a
. The data is stored in a buffer
107
. At the same time, the control circuit
102
causes a C1 correction unit
103
to calculate a syndrome value of each sector to store the calculated syndrome value in a buffer
105
-
1
.
Here, the syndrome value in C1 correction represents an addition result between an integration value of byte data in the sectors and corresponding “C1 correction data” and an addition result between an integration value obtained by weighting the bytes in the sectors and integrating the weighted bytes and corresponding C1 correction data. If syndrome value is “0”, it is considered that no read error exists.
The C1 correction unit
103
performs error correction for data stored in the buffer
107
on the basis of the syndrome value stored in the buffer
105
-
1
.
Upon completion of the calculation and correction of the syndrome value in the C1 correction, the control circuit
102
cancels “C1 correction data” because “C1 correction data” is unnecessary. The control circuit
102
transfers the information data and “C2 correction data” from the buffer
107
to a C2 correction circuit
104
.
The C2 correction circuit
104
calculates syndrome values in the regions A1 to A256 to store the calculated syndrome values in a buffer
105
-
2
.
Here, the syndrome value in C2 correction represents an addition result between an integration value of byte data in the regions and corresponding “C2 correction data” and an addition result between an integration value obtained by weighting the bytes in the sectors and integrating the weighted bytes and corresponding “C2 correction data”. If syndrome value is “0”, it is considered that no read error exists.
In error correction performed by the C1 correction unit
103
, when the number of error bits in a sector to be corrected is larger than the number of error bits which can be maximally corrected as “C1 correction data”, the C2 correction circuit
104
solves a predetermined equation on the basis of the syndrome value to correct error bits of the corresponding region of the regions A1 to A256.
Upon completion of the calculation of the syndrome value in the C2 correction, the control circuit
102
cancels “C2 correction data” because “C2 correction data is unnecessary.
The moment data transfer from the data reader
101
to the buffer
107
and an error correcting process are performed, the control circuit
102
forms a path between a buffer
108
and the host computer
110
by means of a switching circuit
109
. As a result, error-corrected information data stored in the buffer
108
is transferred to the host computer
110
.
However, the above floppy disk drive requires at least 20 k(kilo) byte×2=40 kbyte as the bytes of the buffers
107
and
108
. In addition, since the C1 correction unit
103
, the C2 correction circuit
104
, and the buffer
105
are required, a conventional floppy disk drive
100
increases in circuit scale, and the cost cannot be easily reduced.
Furthermore, even if an error does not occur in data reading, upon completion of a loading operation, 20-kbyte information data is transferred to the host computer
110
, a disadvantage being that the conventional floppy disk drive
100
requires a long time to read/transfer the information data.
SUMMARY OF THE INVENTION
The present invention has been made under the above background, and has as its object to provide a recording/reproduction system such as a floppy disk drive in which the costs can be reduced by reducing the memory capacity in the device such as a floppy disk, and a reading/transferring rate of the information data can be increased.
In order to achieve the above object, according to the present invention, a recording/reproduction system comprises: a recording/reproduction device including a reading mechanism to read information data stored in a floppy disk and constituted by a plurality of byte data and first inspection data and second inspection data to detect an error of the information data, a first calculation mechanism to calculate a first syndrome value from the byte data and the first inspection data, a first error correction mechanism to perform error correction for the information data on the basis of the first syndrome value, and a second calculation mechanism to calculate a second syndrome value from the byte data and the second inspection data; and a computer including a second error correction mechanism to perform error correction for the information data on the basis of the second syndrome value.
According to the present invention, a recording/reproduction system is characterized by comprising: a recording/reproduction device including a reading mechanism to read information data stored in a floppy disk and constituted by a plurality of byte data and first inspection data and second inspection data to detect an error of the information data, a first calculation mechanism to calculate a first syndrome value from the byte data and the first inspection data, and a first error correction mechanism to perform error correction for the information data on the basis of the first syndrome value; and a computer including a second calculation mechanism to calculate a second syndrome value from the byte data and the second inspection data, and a second error correction mechanism to perform error correction for the information data on the basis of the second syndrome value.
REFERENCES:
patent: 4607367 (1986-08-01), Ive et al.
patent: 4785451 (1988-11-01), Sako et al.
patent: 5068855 (1991-11-01), Kashida et al.
patent: 5687182 (1997-11-01), Shikakura
patent: 5996109 (1999-11-01), Shikakura
patent: 2-112033A (1990-04-01), None
Nasu Masahiro
Sugawara Takayuki
Alps Electric Co. ,Ltd.
Baker Stephen M.
Brinks Hofer Gilson & Lione
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