KR101203906B1 - Method for sending data in optical disc drive capable of changing mode - Google Patents

Abstract

The present invention relates to a data transmission method in an optical disk drive capable of switching modes. In one embodiment of the present invention, when a read command is received from a connected host, check whether an address included in the command points to a file system area of a predetermined file system, and the address included in the command is within the file system area. When it is confirmed that the data is found, the data obtained by converting the file information on the files recorded on the optical disk into the predetermined file system can be transmitted to the host. When the address included in the command indicates an address in which an address table in which file data is recorded in the file system area is written, an address included in the command using file information sorted based on a start address. Search for a file corresponding to the table indicated by, generate an address table of the data of the searched file, and transmit the generated address table to the host. If an error occurs more than a predetermined number of times for the same data when reading data from the optical disc, dummy data may be generated and transmitted to the host. Thus, the operation mode can be automatically switched when the optical disc drive is connected to a device having a USB input other than a PC.

Description

How to transfer data from an optical disc drive capable of mode switching {Method for sending data in optical disc drive capable of changing mode}

The present invention relates to a data transfer method in an optical disk drive capable of mode switching, and more particularly, to an optical disk drive that can be used in a device having a USB input other than a PC.

Optical discs such as CDs (Compact Discs), DVDs (Digital Versatile Discs), and BDs (Blu-ray Discs) are portable, removable, and record and store large amounts of data. Recordable optical disc drives are widely used as peripherals for desktop or notebook computers.

In addition, as desktop computers become slimmer and notebook computers become thinner in recent years, external optical disk drives, not internal optical disk drives, have become popular, in which case an external optical disk drive can be used in multiple computers. There is an advantage that can be divided into peripheral devices.

An external optical disk drive can be connected to a computer via a USB (Universal Serial Bus) interface to send and receive data.

In recent years, TVs and various AV devices provide a function of reading and playing data stored in a flash memory such as an SD or a memory stick or an external hard disk through a USB interface so as to expand the width of a video or audio source.

However, although the conventional external optical disk drive is provided with a USB interface for connecting to an external device, it can only be used by connecting to a computer and cannot be used even when connected to other devices.

Accordingly, the present invention has been made to solve the above problems, and an object of the present invention is to provide an optical disk drive that can be used in a device having a USB input.

Another object of the present invention is to provide a method of switching the operation mode of an optical disk drive to be connected to a device having a USB input.

Still another object of the present invention is to provide a method of converting a file system of an optical disk so that a USB device connected to the optical disk drive can access data stored on the optical disk.

It is still another object of the present invention to provide a method of reading and transferring data on an optical disc so that a USB device connected to the optical disc drive can seamlessly reproduce contents recorded on the optical disc.

In the optical disk drive according to an embodiment of the present invention for achieving the above object, in the data transfer method, when a read command is received from a connected host, the address included in the command is a file system area of a predetermined file system Checking that it points to; And when it is determined that an address included in the command is in the file system area, transmitting the data converted from the file information on the files recorded on the optical disk to the predetermined file system to the host. Characterized in that made.

In one embodiment, the file information for the files recorded on the optical disk prior to the reception of the command is converted to a predetermined file system and stored in the memory, the address included in the command is file information in the file system area Indicates the recorded address, the converted file information stored in the memory can be transmitted.

In one embodiment, the converted file information may include the number of files included in the disk, file name, file size, start address of data, attribute, time information of each file, wherein the optical disk When the file information for the files recorded in the file is converted into the predetermined file system, the start address of the data may be changed to a value obtained by adding at least the size of the file system area to the start address of the file recorded on the optical disk. .

In one embodiment, the converted file information may be additionally stored based on the start address of each file data, wherein only the file name, the start address of the data, and the file size of the file information may be stored. .

In an embodiment, when an address included in the command indicates an address in which an address table in which addresses of data of a file are recorded in the file system area is written, the file information sorted based on the start address is used. A file corresponding to a table indicated by an address included in the command may be searched, an address table of data of the searched file may be generated, and the generated address table may be transmitted to the host.

In an embodiment, when it is determined that the address included in the command is not within the file system area, data corresponding to the address included in the command may be read from the optical disc and transmitted to the host. Data may be read from an address included in the command minus the size of the file system area.

In an embodiment, if an error occurs more than a predetermined number of times for the same data when reading data from the optical disc, dummy data may be generated and transmitted to the host.

In one embodiment, data is recorded on the optical disc according to ISO1996 or UDF file system, and the predetermined file system may be FAT32.

According to another embodiment of the present invention, an optical disk drive includes a loader for reading data from or writing data to an optical disk; An interface connected with the host; And when a read command is received from the host through the interface, check whether an address included in the command points to a file system area of a predetermined file system, and if the address included in the command is within the file system area. And a controller for transmitting the data converted from the file information on the files recorded on the optical disk to the predetermined file system to the host through the interface.

Thus, when the optical disc drive is connected to a device having a USB input other than a PC, the operation mode can be automatically switched.

In addition, optical disc drives can be used in devices with USB inputs other than PCs.

1 illustrates a configuration of an optical disk drive to which the present invention is applied.
2 is a flowchart illustrating a method of switching an operation mode of an optical disk drive to a USB mode according to an embodiment of the present invention.
3 illustrates an embodiment in which two interfaces are provided to switch an operation mode of an optical disc drive.
4 is an operation flowchart illustrating a process of converting a file system of an optical disk while the optical disk drive switches to a USB mode according to an embodiment of the present invention.
5 is a flowchart illustrating a method of sorting file information based on a start address of each file.
6 is a flowchart illustrating an operation of a method of transferring a file system converted to FAT32 format and data recorded on an optical disk to a connected USB host according to an embodiment of the present invention.
7 compares the conventional method and the method according to the present invention with respect to a method of processing when a read error occurs when reading and transmitting data of an optical disc.

Hereinafter, an embodiment of a data transmission method in an optical disk drive capable of switching a mother mode according to the present invention will be described in detail with reference to the accompanying drawings.

Since optical disc drives have been used only as peripherals for computers until now, they can be connected using Enhanced-Integrated Drive Electronics (E-IDE) or Serial Advanced Technology Attachment (SATA) when used for internal use and USB when used for external use. It is also connected to a computer using the small computer system interface (SCSI).

In addition, data is recorded on an optical disk in the ISO9660 or Universal Disk Format (UDF) file system, which is different from the file system supported by the computer's operating system (OS), so that the OS runs on the OA rather than directly accessing the disk. A program (e.g. Nero) accesses the disk to write or read data on the disk. In other words, the file conversion of the disk is done by the connected computer and not by the optical disk drive.

Accordingly, the conventional external optical disk drive converts the data of the ISO9660 or UDF file system into USB or SCSI format and transfers the data to the host when the data recorded on the disk is transferred to the host computer connected by USB or SCSI method. When receiving data, data converted to ISO9660 or UDF by the host (a program running in the host computer's OS) is transferred in the USB or SCSI format encapsulated.

However, ordinary A / V playback devices with USB inputs, rather than computers with OS or programs running on them, use the FAT32 file system and do not include the ability to convert the file system of the data. Even if connected via USB, data on other file systems recorded on the optical disc cannot be accessed.

The optical disc drive according to the present invention is simply a mode (ODD mode) which is connected to a computer (or a device having a similar function) so that not only a computer but also a USB device having a USB input can access data recorded on the disc. Two modes of operation are provided, including a mode (USB mode) connected to a USB device (USB host) that only plays data from the connected USB media, and it is determined whether the connected device is a computer or a USB host to switch the operation mode. In addition, when switching to USB mode, the file system of the data recorded on the disk can be converted to the file system used by the USB host and transferred to the connected USB host so that the connected USB host can access the data recorded on the disk. .

1 shows a configuration of an optical disk drive to which the present invention is applied.

The optical disk drive 100 according to the present invention includes a loader 10 for driving an optical pickup, a spindle motor, a sled motor, and the like, for recording data to or reading data from the optical disk, and connecting with an external device. An interface 20, a memory 30 for temporarily storing data, a timer 40, and a controller 50 for controlling each element, determining an operation mode, switching an operation mode, and converting a file system. Can be configured.

First, a method of converting the operation mode of the optical disk drive will be described.

In order for the optical disk drive to be used in a computer or a USB host other than the computer, it is necessary to switch the operation mode to the ODD mode or the USB mode.

The first method of switching the operation mode is to automatically switch the operation mode to the USB mode by separating commands coming from the computer or the USB host when the optical disk drive is connected to the computer or the USB host other than the computer.

When an optical disc drive is connected to a computer via a USB interface, the computer receives commands from the connected computer for Get Event / Status Notification, Get Configuration, and Mode Sense 2A pages. Therefore, it is possible to determine whether the connected device is a computer or a general USB host by receiving the corresponding command.

2 is a flowchart illustrating an embodiment of automatically switching to a USB mode.

When power is applied to the optical disk drive, the controller 50 controls the loader 10 to recognize the inserted disk (S210). In the state in which power is applied to the optical disk drive, the interface 20, for example, USB If the interface is newly connected to the external device, step S210 may be omitted.

The controller 50 controls the timer 40 to start time counting (S220), and the computer of Get Event / Status Notification, Get Configuration, Mode Sense 2A page while counting a predetermined time, for example, 3 seconds. In order to check whether the command is transmitted through the interface 20 (S230), steps S220 and S230 may be executed in parallel with step S210.

If at least one of the Get Event / Status Notification, Get Configuration, and Mode Sense 2A page commands is received within 3 seconds (YES in S230), the controller 50 switches the drive type to ODD to enter the ODD mode. In operation S250, the controller 20 attempts to connect with an external device by controlling the interface 20.

On the other hand, if no command is received within 3 seconds (NO in S230), the controller 50 switches the drive type to USB to enter the USB mode (S260), and controls the interface 20 to once with an external device. The connection is disconnected (S270), after which the file system is converted.

The second method of switching the operation mode is to switch to the USB mode when a specific button provided on the outside of the optical disk drive is pressed. The specific button is connected to a global input output (GIO) terminal of the controller 50, and when a specific button is pressed, the GIO terminal becomes high (or low) to recognize a mode switch request. When the GIO terminal becomes high (or low), the controller 50 switches the drive type to USB to enter the USB mode, and controls the interface 20 to disconnect the external device once.

A third method of switching the operation mode is to switch to the USB mode when a specific button of the optical disc drive, for example, an eject button, is operated in a predetermined pattern. The predetermined pattern may be a case where the eject button is pressed two or more times consecutively within a predetermined time, or the eject button is continuously pressed for another predetermined time. The controller 50 sets the basic operation mode to the ODD mode, but when the eject button is detected to be operated in a predetermined pattern, the controller 50 switches the drive type to USB to enter the USB mode, and controls the interface 20 to externally Disconnect from the device.

As a fourth method of switching the operation mode, as shown in FIG. 3, two interfaces 20 are provided, one for the ODD mode port (port # 1) and the other for the USB mode port (port # 2). ) To use. Port # 1 / # 2 is connected to the GIO terminal of the controller 50, and when an external device is connected to port # 2 of the interface 20, the GIO terminal of the controller 50 becomes high (or low), The controller 50 detects this, enters the USB mode by switching the drive type to USB, and controls the interface 20 to disconnect the external device. On the other hand, when the controller 50 detects that the GIO terminal becomes low (or high), the controller 50 switches the drive type to ODD to enter the ODD mode, and attempts to connect to an external device by controlling the interface 20.

On the other hand, the optical disk drive records data on the optical disk using the ISO9660 or UDF file system, and the general USB host uses the FAT32 file system to record or play back data on hard disks, flash memories, and the like.

Therefore, when the optical disc drive is connected to a USB host with a USB input instead of a computer, and the operation mode is switched to the USB mode, the file system of the optical disc is converted so that the connected USB host can control the data recorded on the optical disc. It is necessary to do

When the optical disk drive switches the operation mode to the USB mode, the optical disk's file system is converted to FAT32, and the converted file system is transferred to the connected USB host so that the USB host can access the files recorded on the optical disk. Can be played back.

4 is an operation flowchart illustrating a process of converting a file system of an optical disk while the optical disk drive connected to the general USB host is switched to the USB mode.

When the optical disk is inserted into the optical disk drive connected to the USB host having the USB input instead of the computer (S410), the controller 50 controls the interface 20 to disconnect the connected USB host (S420) and the operation mode. To switch from the default mode ODD mode to the USB mode (S430), the loader 10 is controlled to search the file system inside the optical disk (S440).

If the file system of the optical disk is ISO9660 or UDF (YES in S450), the controller 50 converts the file system for each file included in the disk into FAT32 format, and controls the loader 10 to write to the disk. The file information of each file is read and converted to FAT32 and converted to FAT32 and stored in the memory 30 such as DRAM (S460), and repeated until the file system conversion for all files included in the disk is completed (S470).

The controller 50 stores the number of files stored on the optical disk, file name, file name length, data start address, file size (or length), attributes (file or folder), time information and the like for each file. The system information is generated in the FAT32 format and stored in the memory 30. The start address of each file is a value that is moved backwards or more than the size occupied by the file system information (and the FAT table) for all files, that is, on the optical disk. It can be converted to the sum of the original starting address written and the size of the file system information (or the size of the file system area where the file system information is written), and the size of the file system information at the requested address when reading actual data from the optical disc. Data can be read from the address subtracted by.

Thereafter, the controller 50 stores the file information converted into the FAT32 file system in the memory 30 and sorts some of the file information (file name, start address, file size) in the order of start address. Save additionally (S480), and try to connect to the USB host again (S490).

The optical disk drive transfers the file information converted to a FAT32 format file system to a USB host, and then, upon request of the USB host, a FAT table (for example, a predetermined number of sectors included in the file) for the desired file. All addresses where data is written are listed in a table representing each length (4 bytes). Data must be generated and transmitted to the USB host. In the FAT32 file system, the address where the FAT table for each file is written is determined by the start position and size of each file, and when the USB host requests the FAT table data of the desired file, it is based on the start position and size of each file. Command to request reading of the address where the FAT table data is recorded.

Accordingly, the optical disk drive sorts the information of each file converted in steps S450 to S470 in the start address order so that a file corresponding to the FAT table indicated by the address included in the command transmitted by the USB host can be quickly searched. It is advantageous. 5 shows a method of sorting file information according to the start address of each file. In the file information listed in the order of each file name, the next file and the start address are sequentially compared to the file in the order of the lowest address to the highest address. Change the order of the information and save it.

Next, a method of transferring a file system converted to FAT32 format and data recorded on an optical disk to a connected USB host by switching to the USB mode will be described. FIG. 6 shows an operation flowchart thereof.

The first time a USB host accesses a USB medium, such as a USB HDD or USB memory, it sends a command to request file system information for all files recorded on the USB medium to verify the data stored on that medium. This is a read command that uses the area where the file system information specified in the standard is stored as a destination, and correspondingly includes the number of files of data stored in the media, the name of each file, the length of the file name, the file size, the start address, the attribute, the time, and the like. File system information is returned.

In addition, the USB host requests a transfer of a FAT table listing addresses of all sectors included in the desired file when accessing the desired file after checking the information on the directory, the file, and each file included in the USB medium. When the FAT table is transmitted, a command for requesting data transmission from a desired address is transmitted with reference to the FAT table, thereby reproducing the transmitted data. The FAT table of each file is also recorded in the file system area separately from the area where data is stored, and the file information of all files included in the media, that is, the FAT table of the file from the start address and size of each file is recorded. You can calculate the address.

When the file system for the data recorded on the optical disk is converted to the FAT32 format accessible by the USB host and then connected to the USB host, the controller 50 connects the optical disk in the USB mode through the interface 20 from the USB host. It is checked whether a command (Read CMD) for reading data of the disc inserted into the drive is transmitted (S610).

When the controller 50 receives the read CMD (YES in S610), the controller 50 checks the destination address of the read CMD sent by the USB host, and summarizes the file system area defined in FAT32, that is, the files recorded on the disk. It is determined whether the information and the FAT table are recorded in the file system area (S620).

When the address included in the Read CMD sent by the USB host points to the address where the file information is recorded in the file system area (YES in S630), the controller 50 is already converted to FAT32 format and stored in the memory 30. The information is transmitted to the USB host through the interface 20 (S640).

On the other hand, if the address included in the Read CMD sent by the USB host points to the address where the FAT table is written in the file system area (NO in S630), that is, the USB host has already obtained file information on the data recorded on the optical disk. After requesting the transfer of the FAT table data of the desired file based on this, the buffer (buffer provided in the memory 30 or the controller 50) for temporarily storing the data to be transmitted to the connected USB host is cleaned (S650). In step S480, the file information listed in the start address order is searched to find the file information corresponding to the FAT table indicated by the address included in the read CMD (S660), and the FAT for the file is based on the start address and size information of the file. The table is generated and transmitted to the USB host through the interface 20 (S670). Steps S660 and S670 will be described later in detail.

On the other hand, if the destination address of the Read CMD sent by the USB host is not the area in which the file system is recorded (NO in S620), that is, the USB host will display the file information for the data written to the optical disk and the FAT table data for the desired file. In case of requesting the transmission of the data of the corresponding file based on the information already acquired, the controller 50 reads the data of the transmission request address from the optical disk and transmits the data to the USB host (S680). The file system information is requested at the requested address. Data is read from the address minus the size (or the size of the file system area) and transferred to the USB host. The case where an error occurs while reading data from the optical disc will be described in detail later.

The steps S660 and S670 will be described.

In the medium according to the FAT32 file system, a MBR (Mater Boot Record), a Boot Sector, a FAT table, a file system area in which directory / file information is recorded, and a data area in which actual file data is recorded are sequentially formed. Is recorded.

As the FAT table increases in size as the amount of data written to the medium (the number of sectors written to the data area) increases, the FAT table for each file is converted to memory when the file system of the optical disk is converted. 30 cannot be stored, and a new FAT table corresponding to the requested file is created every time the USB host requests it.

In the FAT table area, a FAT table for each file is generated and recorded in ascending order of start addresses. For example, as shown in FIG. 5, a sector corresponding to a file size having a start address of File # 1 is 100 and is shown in FIG. The number is 50 (100, 50), File # 2 is (450, 100), File # 3 is (300, 150), File # 4 is (150, 100), File # 5 is (250, 50), File If # 6 is (550, 100), a FAT table with 50 (sectors) x 4 (bytes / sectors) = 200 (bytes) for the file # 1 having the earliest starting address is a predetermined address (A) in the FAT table area. FAT table for File # 5, which is written from, and then 100 x 4 = 400 (bytes) of FAT table for File # 4 with the next highest starting address, followed by 50 x 4 = 200 (bytes) of FAT table, FAT table for File # 3 with 150 x 4 = 600 (bytes), FAT table for File # 2 with 100 x 4 = 400 (bytes), FAT table for File # 6 with 100 x 4 = 400 (bytes) This is recorded.

The USB host receiving the directory / file information requests a FAT table for the file in order to access the desired file. The FAT table for the file is written based on the file information (start address and size of each file). Compute the address and send a Read command containing the calculated address. In the previous example, when the USB host requests a FAT table of File # 3, it sends a Read command whose parameters are the file where the FAT table of File # 3 is written and the size of the FAT table. The recorded address is the FAT table size (200 (File # 1) + 400 (File # 4) + 200 (File # 5)) of the files before the start address of the data of File # 3 and the first FAT table is written. Can be obtained by adding up the start address (A).

When the optical disk drive receives a Read command requesting the transfer of FAT table data, the optical disk drive determines whether the command is a file system area, an address where file information is recorded, or an address where a FAT table is written from an address included in the command. If the FAT table corresponds to the recorded address, it must search for which file the FAT table corresponds to.

When the file information of the file system converted to FAT32 format is stored in the memory 30, sorted by file name, the controller 50 reads start address and size information for all files from the first file and based on each file, Calculate the address where the FAT table data will be written, and compare the calculated address with the address included in the Read command to find the file corresponding to the FAT table desired by the USB host.

However, when the file system of the optical disk is converted into file information of FAT32 format and stored in the memory 30, when the file information of each file is sorted based on the start address, the controller 50 stores the file information in the memory 30. Based on the file information (file size), it is possible to calculate the address where the FAT table for the file is written in order from the file with the earliest starting address. Therefore, the Read command is compared to the address included in the Read command. You can quickly find the file in the FAT table that corresponds to the address contained in. That is, as shown in FIG. 5, if the file information is arranged based on the start address, the USB host may quickly search for a file corresponding to the requested FAT table.

When the USB host finds a file corresponding to the requested FAT table, the controller 50 may generate new FAT table data based on the start address and length information of the file and transmit the data to the USB host through the interface 20. .

Next, a method of reading and transmitting data requested by the USB host will be described. 7 compares the conventional method and the method according to the present invention in a method of processing when a read error occurs while reading and transmitting data of an optical disc.

The optical disc drive reads data from the optical disc at the address requested by the USB host and transmits the data to the USB host. Conventionally, if the optical disc is defective or the decoding of the read signal fails due to poor playback signal quality, the optical disc drive retries. As the retry progresses, a time delay occurs, and when the retry is repeated for a predetermined number of times and exceeds the retry limit, an error is reported, so that playback of the corresponding content is stopped in the USB host.

A USB host, not a computer, is an MP3 player, PMP, TV, or AV player that receives and plays music, movies, pictures, and text stored on a storage medium connected via USB. In some cases, even if there is an error in some data, the playback without interruption without interruption may be more in accordance with the user's convenience.

Therefore, when the optical disk drive according to the present invention, for example, reads video content and transmits it to the USB host in the USB mode, the optical disk drive may retry a predetermined number of times (for example, four times) while decoding the signal read from the optical disk. If decoding fails, dummy data can be generated and sent to the USB host. If the data is transferred correctly after the dummy data, the USB host can play without interruption as it generates some mosaic noise in the video being played.

The above-described preferred embodiments of the present invention are disclosed for purposes of illustration, and those skilled in the art can improve, change, and substitute various other embodiments within the technical spirit and scope of the present invention disclosed in the appended claims below. Or addition may be possible.

10: Loader 20: Interface
30: timer 40: memory
50: controller 100: optical disk drive

Claims (18)

If it is determined that the connected host is not a computer, converting file information about files recorded on an optical disc into a predetermined file system accessible by the host and storing the file information in a memory;
If a read command is received from the host, checking an address included in the command; And
And transmitting the converted file information stored in the memory to the host when the address included in the command indicates an address in which file information in a file system area of the predetermined file system is recorded. How to transfer data from The method of claim 1,
The storing step,
Disconnecting from the host prior to the conversion; And
Storing the converted file information in a memory and attempting to reconnect with the host. The method of claim 1,
The converted file information includes a number of files included in the disc, a file name, a file size, a start address of a data, an attribute, and time information for each file. . The method of claim 3, wherein
When converting file information on the files recorded on the optical disk into the predetermined file system, the start address of the data is added to the start address of the corresponding file recorded on the optical disk, at least the size of the file system area. Data transmission method of an optical disk drive, characterized in that for changing. The method of claim 1,
The storing may further include storing the converted file information by sorting the converted file information based on a start address of each file data. 6. The method of claim 5,
And storing only a file name, a start address of a data, and a file size among the file information when sorting based on the start address. 6. The method of claim 5,
When the address included in the command indicates an address in which an address table in which file data of the file is recorded in the file system area is recorded, the file information sorted based on the start address is included in the command. And searching for a file corresponding to a table indicated by an address, generating an address table of data of the found file, and transmitting the generated address table to the host. The method of claim 1,
If it is determined that the address included in the command is not within the file system area, the method further comprises reading data corresponding to the address included in the command from the optical disc and transmitting the data to the host. To transfer data from an optical disc drive. The method of claim 8,
When reading data from the optical disc, reading data from an address subtracted from the size of the file system area from an address included in the command. The method of claim 8,
And generating dummy data and transmitting the dummy data to the host if an error occurs more than a predetermined number of times of the same data when reading data from the optical disk. The method of claim 1,
The data is recorded on the optical disc according to ISO1996 or UDF file system, and the predetermined file system is FAT32. A loader for reading data from or writing data to the optical disk;
An interface connected with the host;
A memory for storing file information converted to a predetermined file system; And
It is determined whether the host connected through the interface is a computer, and if it is determined that the connected host is not a computer, the file information on the files recorded on the optical disk is converted into the predetermined file system accessible by the host, and the Store in a memory, and when a read command is received from the host through the interface, check an address included in the command, and the address included in the command is an address in which file information in a file system area of the predetermined file system is recorded. And a controller for transmitting the converted file information stored in the memory to the host through the interface. 13. The method of claim 12,
The converted file information includes a number of files included in the disc, and a file name, a file size, a start address of a data, an attribute, and time information for each file. The method of claim 13,
And when the controller converts file information into the predetermined file system, the start address of the data is changed to a value obtained by adding at least the size of the file system area to the start address of the corresponding file recorded on the optical disk. Disk drive. The method of claim 13,
The controller may further store the file name, the start address of the data, and the file size of the converted file information based on the start address of each file data and store them in the memory. 16. The method of claim 15,
When the address included in the command indicates an address in which an address table in which file data is recorded in the file system area is written, the controller uses the file information arranged based on the start address, and the command is used. And searching for a file corresponding to a table indicated by an address included in the table, generating an address table of data of the found file, and transmitting the generated address table to the host through the interface. 13. The method of claim 12,
When it is confirmed that the address included in the command is not within the file system area, the controller controls the loader to read data corresponding to the address included in the command from the optical disc, and to control the interface. And transmit the read data to the host. 18. The method of claim 17,
And the controller generates dummy data and transmits the dummy data to the host if an error occurs more than a predetermined number of times when the data is read from the optical disk.

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