JPH06202819A - Disk device - Google Patents

Abstract

PURPOSE:To speedily send read-out data to a host device by immediately sending data, which are read from a buffer memory, to the host device without writing them back to the buffer memory when those data are corrected. CONSTITUTION:When bits DO and D7 have errors among one-byte user data D7-DO transferred to an SCSI controller 19, an error detection unit 18 generates one-byte error information showing the positions of those error bits. The pieces of error information D7-D are transferred to an SCSI controller 19 synchronously with unit data. Then, an eclusive OR circuit 191 outputs corrected data by ORing the user data D7-DO and the pieces error information D7-D. The corrected data outputted from the exclusive OR circuit 191 are temporarily stored in a FIFO circuit 192 and sent to a host computer 2 successively from these corrected data.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to various disk devices for storing information.

[0002]

2. Description of the Related Art In computer systems, various disk devices such as magnetic disk devices and optical disk devices are often used as storage devices.

Usually, such a disk device is provided with a control unit, a buffer memory, an error correction unit, etc. in the device. Then, upon receiving a recording data read command from the host computer, which is a higher-level device, the control unit
Recording data is read from the information recording medium, for example, in units of one sector. The read data is transferred to the buffer memory and the error correction unit.

The buffer memory temporarily stores the transferred data. The error correction unit sequentially detects bit errors in the transferred data. When a bit error is detected,
The error information indicating the position of the error bit is output to the control unit. The control unit inputs the error information, reads the corresponding data from the buffer memory, and corrects the error bit. The corrected data is written back in the buffer.

In the disk device, such correction processing is sequentially repeated byte by byte. When the error correction of all the data in the buffer memory is completed, the corrected data is sent to the host device.

[0006]

As described above, in the conventional disk device, the data read from the information recording medium is temporarily stored in the buffer memory, and after error correction of all data is completed, the data is sent to the host device. I was trying to do it.

Therefore, there is a problem that the host device takes time from when the read command is given to the disk device until the read data is actually obtained.

It is an object of the present invention to solve the above problems and to provide a disk device which can quickly send read data to a higher-level device.

[0009]

To this end, the present invention is characterized in that the data in the buffer memory is sequentially read out, the bit error is corrected, and the corrected data is immediately sent to the host device. Is.

[0010]

Since the corrected data is sent to the host device without being written back to the buffer memory, the data read from the information recording medium can be quickly sent to the host device after receiving the read command from the host device. Become.

[0011]

Embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram of an optical disc system according to an embodiment of the present invention. In the figure, an optical disk device 1 is used as one external storage device of a host computer 2 which is the above device.

In the optical disc device 1, the optical disc drive unit 11 drives the optical disc to rotate and read the recorded information by an optical pickup or record new information. The ESDI unit 12 is an ESDI (Enhanced Small D
The control signal and data are input and output by an "device interface". Optical disc controller 13
Controls the optical disk drive unit 11 via the ESDI unit 12 to execute a data recording / reproducing operation.

The CPU 14 monitors and controls each section in the apparatus. The ROM 15 stores the control program of the CPU 14, and the RAM 16 stores
Various control data are temporarily stored when the CPU 14 operates.

The buffer memory 17 temporarily stores the data to be recorded on the optical disc and the read data. The error detection unit 18 detects a data error in the read data. The SCSI controller 19 is a SCSI (Small Computer).
It is connected to the host computer 2 by a system interface, receives command information and data to be recorded from the host computer 2, and sends the read data.

As shown in FIG. 2, the SCSI controller 19 has 8-bit data D0 to D7 as parallel signals.
Is formed by two signal lines. User data read from the buffer memory 17 is input to one signal line, and error information output from the error detection unit 18 is input to the other signal line.

In the SCSI controller 19, eight exclusive OR circuits 191 are arranged, and the same bit of each input data is input to each circuit. The output of each circuit is the FIFO circuit 192.
Has been entered in. The output of the FIFO circuit 192 is
It is sent to the host computer 2.

Next, the read operation of the recording data of the optical disk device 1 having the above-mentioned configuration will be described.

Now, it is assumed that the host computer 2 sends a recording data read command to the optical disk device 1.
In this read command, the sector number of the optical disk is designated.

Then, as shown in FIG. 3, the optical disk device 1 executes the read control of the designated sector of the optical disk according to the read command. That is, in this case, the read command is transferred to the optical disk controller 13 via the SCSI controller 19. The optical disk controller 13 receives the optical disk through the ESDI unit 12.
The drive unit 11 is controlled to read the record information of the designated sector of the optical disc (process 101). At this time, ECC for data error correction together with user data
(Error Correction Code) is read.

The optical disc controller 13 transfers the read user data to both the buffer memory 17 and the error detection unit 18 (102). After the transfer, the ECC is further transferred to the error detection unit 18 (process 103).

After this, the optical disk controller 13
A transfer operation is started in which the user data stored in the buffer memory 17 is read byte by byte and sequentially transferred to the SCSI controller 19. At this time, the user data is transferred to the SCSI controller 19 via the signal line shown in FIG. 2 (process 104).

By the way, there is a possibility that a bit error has occurred in the user data and ECC. The error detection unit 18 detects a bit error of user data based on the ECC. Then, the error information indicating the bit error occurrence position is sequentially transferred byte by byte to the SCSI controller 19. At this time, the error information is transferred to the SCSI controller 19 via the signal line shown in FIG. 2 (process 105).

It is assumed that the 1-byte user data D7 to D0 transferred to the SCSI controller 19 is "01011010" as shown in FIG. 4A, for example. If the bits D0 and D7 of the data are incorrect, the error detection unit 18 indicates the position of the error bit as shown in FIG.
Byte error information D7 to D0 "10000001" is generated. The error information D7 to D is transferred to the SCSI controller 19 in synchronization with the user data.

The exclusive OR circuit 191 calculates the exclusive OR of the user data D7 to D0 and the error information D7 to D, and as shown in FIG.
The corrected data "1" is output. This means that the error bit of the user data has been corrected.

In this way, the user data read from the buffer memory 17 becomes the error detection unit 18
Are sequentially corrected by the error information generated in (Processing 10).
6).

The corrected data output from the exclusive OR circuit 191 is temporarily stored in the FIFO circuit 192. Then, the correction data stored in advance is sequentially read and sent to the host computer 2 (process 107).

As described above, in this embodiment, after the user data read from the optical disk is stored in the buffer memory 17, the user data is sequentially read while simultaneously correcting the bit error, and the corrected user data is stored in the buffer memory. The data is sent to the host device immediately without being written back.

As a result, after receiving the read command from the host computer 2, the user data read from the optical disk can be quickly sent to the host computer 2.

Further, by generating the error information indicating the position of the error bit of the user data byte by byte and calculating the exclusive OR of the error information and the user data,
Since the user data is corrected, the correction process can be executed with a relatively simple circuit.

Further, the error detection unit 18 for generating error information is composed of an independent hardware unit,
Exclusive OR circuit 191 for executing exclusive OR operation
Are arranged in the SCSI controller 19. In this case, the unit configuration of the device is the same as that of the conventional device, so that the process of the present embodiment can be executed by only changing a part of the conventional device.

In the above embodiment, the error correction of the user data is executed by the exclusive OR operation of the error information indicating the position of the error bit and the user data, but it is executed by another correction method. You may do it. In this case, any correction method capable of performing error correction on the user data sequentially from the beginning can be applied to the present invention.

Although the optical disk device has been described as an example, the present invention can be similarly applied to other types of disk devices such as a magnetic disk device.

[0034]

As described above, according to the present invention, when the data read from the buffer memory is corrected, it is immediately sent to the host device without being written back to the buffer memory. After receiving the command, the data read from the information recording medium can be quickly sent to the host device.

[Brief description of drawings]

FIG. 1 is a block diagram of an optical disc system according to an embodiment of the present invention.

FIG. 2 is a circuit configuration diagram of a part of a circuit in the SCSI controller.

FIG. 3 is a flowchart of a read operation of recording data.

FIG. 4 is an explanatory diagram showing an example of a data error correction operation.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical disk device 2 Host computer 11 Optical disk drive unit 12 ESDI unit 13 Optical disk controller 14 CPU 15 ROM 16 RAM 17 Buffer memory 18 Error detection unit 19 SCSI controller 191 Exclusive OR circuit 192 FIFO circuit

Claims (3)

[Claims] 1. A disk device for storing data read from an information recording medium once in a buffer memory, correcting bit errors, and then sending the data to a higher-level device, and reading means for sequentially reading the data stored in the buffer memory. A disk device comprising: an error correction means for correcting a bit error of the read data; and a data transmission means for immediately transmitting the corrected data to the host device. 2. The error correction means detects the bit error of the data and outputs the error information indicating the position of the error bit, and the exclusive OR of the output error information and the data. 2. The disk device according to claim 1, wherein the disk device comprises an arithmetic means for correcting a bit error by arithmetic operation. 3. The error detecting means is one hardware unit, and the arithmetic means is a circuit arranged in the hardware unit for sending the data to a host device. Item 1. The disk device according to item 1.