JPH0667807A - Recorded information reproducing device - Google Patents

Abstract

PURPOSE:To attain prereading with rapid access also in an area whose blocks are recorded in address descending order by switching and controlling the prereading direction of a recorded information prereading means to an address ascending direction or an address descending direction in accordance with a reading address and recording format information. CONSTITUTION:Recording format information expressing the arrangement of respective blocks in a data area and a directory area in a recording medium is the ascending order of addresses or the descending order of addresses is recorded in the optional block of the directory area of the recording medium. The recording format is read out from the recording medium to detect whether the arrangement of respective blocks in the data area and the directory area in the recording medium is the descending order or ascending order of addresses. Thus either one of address ascending order prereading or address descending order prereading is selected to execute prereading.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a read-ahead function of a recorded information reproducing apparatus.

[0002]

2. Description of the Related Art FIG. 1 shows the structure of a disk drive device 2 which is a recorded information reproducing device and a host computer 1 which sends recording information to and reads recorded information from the disk drive device 2. . First, the host computer 1 will be described.

The host computer 1 comprises a ROM 13, a buffer memory 14, a keyboard 15 and a relay means 16 which are connected to a CPU 11 which is a central processing unit via a CPU bus 12. Host computer 1
Further, an external memory 4 for storing a large amount of information is connected to the CPU via a CPU bus 12. Keyboard 1
Reference numeral 5 supplies an information recording / reading command from the user to the CPU 11 via the CPU bus 12.

Next, reading of recorded information from the disk drive device 2 by the host computer 1 will be described. When the recording information read command is issued from the keyboard 15, the CPU 11 supplies the read command together with the read address to the relay means 16 via the CPU bus 12.
The relay means 16 sends the read address and the read command on the CPU bus 12 to the interface bus 3. In response to this read command, the recording information is supplied from the disk drive device 2 to the relay means 16 via the interface bus 3. The CPU 11 is the relay means 16
The record information supplied to the buffer memory 14 is temporarily stored in the buffer memory 14, and then the record information is read from the buffer memory 14 and stored in the external memory 4. The CPU 11 executes the above control according to the software stored in the ROM 13.

Next, the disk drive device 2 will be described. The disk drive device 2 includes a ROM 22, a RAM 23, a buffer memory 24, an error correction circuit 25, a modulation / demodulation means 26, a drive unit 27, and a relay means 28 which are connected to a CPU 21 which is a central processing unit via a CPU bus 22. To be done. The drive unit 27 includes a recording disk 27a, which is a recording medium, and a spindle motor 27 for rotating the recording disk 27a.
b, a pickup 27c for recording and reading recorded information on the recording disk 27a, and a slider motor 27d for moving the pickup 27c in the radial direction of the recording disk 27a. The spindle motor 27b, the pickup 27c, and the slider motor 27d are connected to the CPU bus 22, and the CPU 2
Each of them operates according to the instruction from 1.

Next, reading of recorded information by the disk drive device 2 will be described. When a read command and a read address are supplied from the host computer 1 to the disk drive device 2 via the interface bus 3,
The CPU 21 moves the slider motor 27d to move the pickup 27c to the position corresponding to the read address.
To operate. The pickup 27c reads the recorded information from the recording disk 27a and supplies a read signal to the modulation / demodulation means 26 in response to a read command from the CPU 21. The modulation / demodulation means 26 demodulates the read signal supplied from the pickup 27c in accordance with the demodulation command from the CPU 21, and supplies the obtained demodulated signal to the error correction circuit 25. The CPU 21 temporarily stores the record information obtained by the error correction by the error correction circuit 25 in the buffer memory 24, and then stores it in the buffer memory 24.
The record information is read from and supplied to the relay means 28. The relay means 28 sends this recording information to the interface bus 3.

The CPU 21 controls the ROM 22 as described above.
Run according to the software stored in. RA
M23 is a storage means used for executing the control by this software. FIG. 2A shows a structure of the recording disk 27a. The recording disk has a data area in which a plurality of blocks of data # 1 to data #n are recorded in ascending order of addresses, and a directory in which management information for each of a plurality of information blocks recorded in the data area is recorded. # 1 ~ directory #
A directory area in which a plurality of blocks consisting of n are recorded in descending order of address is constituted.

FIG. 2B shows the recording disk of FIG. 2A linearly in the ascending address direction. When, for example, image information is recorded on the recording disc as described above, adjacent blocks are associated with each other. Further, as shown in FIG. 2B, blocks # 1 to #n, which are blocks recorded in the data area, are recorded in ascending order of address. By utilizing these properties, prefetching of data is performed in reading from the recorded information reproducing apparatus.

FIG. 3 is a diagram showing a read-ahead operation in the data area performed in the apparatus of FIG. Figure 3
3 shows an example of reading data # 3 to # 5 from the blocks in FIG. 2B. First, the host computer 1 makes an initial setting regarding the method of reading the record information when reading the record information. At this time, a command relating to the method of reading the recorded information is transmitted to the disc drive device 2. For example, among the commands relating to the method of reading the record information, the commands relating to prefetching include a prefetch block number setting command (8 bits × 2) as shown in FIG. Disk drive device 2
Sets parameters according to a command relating to the read method of the recorded information. Here, the setting commands for the number of prefetch blocks shown in FIG.
"00000" (upper), "00000010" (lower)
Then, the disk drive device 2 always pre-reads the block two blocks ahead in the read operation.

After the initial setting is completed, when the host computer 1 supplies the read command and the address for reading the data # 3 to the disk drive device 2, the CPU
21 picks up at the position corresponding to this address 2
The slider motor 27d is operated to move 7c. After that, the data # 3 is read by the pickup 27c, and the read data # 3 is modulated / demodulated by the modulation / demodulation means 2
6, sent to the host computer 1 via the error correction circuit 25, the relay means 28 and the interface bus 3. Meanwhile, the CPU 21 continues the movement of the pickup 27c, sequentially reads the data # 4 and the data # 5 appearing next to the data # 3, and stores them in the buffer memory 24, respectively. Next, when the read command and the address for reading the data # 4 are supplied from the host computer 1 to the disk drive device 2, the CPU 21 causes the buffer memory 2 to read.
Data # 4 stored in No. 4 is read out, and the relay means 28
And to the host computer 1 via the interface bus 3. Next, the read command and data # 5 are sent from the host computer 1 to the disk drive device 2.
When the address for reading is supplied, the CPU 21 reads the data # 5 stored in the buffer memory 24 and sends it to the host computer 1 via the relay means 28 and the interface bus 3.

As described above, since the data # 3 to # 5 recorded in the data area are recorded in the ascending order of addresses, the pickup moves the position to the next data while reading the current data. become. As a result, when reading data # 4 and data # 5, high-speed reading is possible without requiring seek time for moving the pickup.

However, directories # 1 to #n in the directory area shown in FIG.
Is in the descending order of the addresses, the directory information read by the prefetch as described above is different from the desired directory information. FIG. 5 is a diagram showing a read-ahead operation in the directory area, which is performed in the apparatus of FIG. 1, in the directory shown in FIG.
This is an example of reading the directories # 3 to # 4.

When the read command and the address for reading the directory # 3 are supplied from the host computer 1 to the disk drive device 2, the CPU 21 causes the slider motor 27d to move the pickup 27c to the position corresponding to this address. To operate. The directory # 3 read by the pickup 27c is sent to the host computer 1 via the modulation / demodulation means 26, the error correction circuit 25, the relay means 28 and the interface bus 3. Meanwhile, the CPU 21 picks up the pickup 27c.
Is continued to be read, and the directories # 2 and # 1 appearing next to the directory # 3 are sequentially read and stored in the buffer memory 24, respectively. Next, a read command and a read address for reading the directory # 4 are supplied from the host computer 1 to the disk drive device 2. However, since the buffer memory 24 does not store the directory # 4, the CPU 21 moves the pickup 27c to a position corresponding to the address for reading the directory # 4, and reads the directory # 4 by the same operation as described above. , And sends the read directory # 4 to the host computer 1. Meanwhile, CPU21
Continues the movement of the pickup 27c, and the directories # 3 and # 2 appearing next to the directory # 4.
Are sequentially read and stored in the buffer memory 24.

As described above, the directories # 2 and # 1 read ahead in reading the directory # 3 and the directories # 3 and # 2 read ahead in reading the directory # 4 are not required by the host computer 1. Since it does not exist, it remains unused in the buffer memory 24. Therefore, when the pre-reading is performed in the area where the blocks are recorded in the address descending order by the conventional pre-reading function, there is a problem that the block different from the desired block is pre-reading, and the pre-reading rather slows the access. .

[0015]

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and provides a recorded information reproducing apparatus capable of prefetching by high-speed access even in an area where blocks are recorded in descending order of address. The purpose is to provide.

[0016]

A data area in which information data is divided into blocks and recorded, and a directory area in which management information is divided and recorded in blocks, the data area or the directory A recording information reproducing apparatus for a recording medium in which each block of the area is recorded in ascending order of address or in descending order of address, and the address of each block of the data area or the directory area recorded from the recording medium is in ascending order. Recording format detection means for detecting whether or not the data is recorded or recorded in descending order, and a predetermined number of information data or management information from the recording medium in accordance with a read command and a read address from a block corresponding to the read address. Recording information pre-reading means for pre-reading and reading up to the block. And a look-ahead direction control means the controls switching the prefetch direction address ascending direction or address descending direction of the record information read-ahead means according to Les and the recording format information.

[0017]

It is detected by reading information from the recording medium whether the arrangement of blocks of the data area and the directory area of the recording medium is in ascending order of addresses or in descending order of addresses, and the ascending order of addresses is detected based on the detection result and the read address. Either prefetching or prefetching in descending order of address is selected to prefetch.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 6 shows an example of the format of one directory in the directory area of the recording medium. In FIG. 6, one of 16 kilobytes in one directory
At the 0th bit and the 1st bit of the byte (8 bits), information indicating the arrangement order of blocks for each address of the data area and the directory area of this recording medium is recorded. For example, when the arrangement of blocks in the data area of this recording medium is in ascending order of addresses, the first bit is set to "1", and when the arrangement of blocks is in descending order of addresses, the first bit is set to "0". Furthermore, if the arrangement of blocks in the directory area of this recording medium is in ascending address order, the 0th bit is set to "1", and if it is in descending address order, the 0th bit is set to "0".

As described above, in the recording medium of the recording information reproducing apparatus according to the embodiment of the present invention, whether each block of the data area and the directory area is recorded in ascending order of address or in descending order of address. The recording format information indicating the above is recorded in any one block in the directory area. next,
The recorded information reproducing apparatus of the present invention will be described.

FIG. 7 is an example showing the format of the prefetch setting command in the recorded information reproducing apparatus of the present invention. FIG. 7A shows a setting command format for prefetching in the data area. In FIG. 7A, the 7th bit is set to "1" when the prefetch is performed in the data area of the recording medium, and the 7th bit is set to "0" when the prefetch is not performed in the data area. Set. Furthermore, when prefetching is performed in ascending address order in the data area, the 6th bit is set to "1",
When performing prefetching in the descending order of addresses in the data area, the 6th bit is set to "0". The number of prefetch blocks in the data area is set in bits 0 to 5.

FIG. 7B shows a setting command format for prefetching in the directory area. In FIG. 7B, the 7th bit is set to "1" when the prefetch is performed in the directory area of the recording medium, and the 7th bit is set to "0" when the prefetch is not performed in the directory area. Set. Further, the 6th bit is set to "1" when prefetching is performed in ascending address order in the directory area, and the 6th bit is set to "0" when prefetching is performed in descending address order in the directory area. The number of prefetch blocks in the directory area is set in bits 0 to 5.

FIG. 8 shows an example of the prefetch setting command created by the above setting command format. Figure 8
In the above, since the 7th bit of the prefetch setting command “00000000” is “0”, it functions as a prefetch OFF command. Prefetch setting command "1000001
Since "0" is the first bit in the ascending order because the 7th bit is "1" and the 6th bit is "0", the prefetch block number is 2 because 5th to 0th bits are "000010".
Functions as a block address ascending prefetch command.

The prefetch setting command as described above is sent from the host computer to the recorded information reproducing apparatus at the time of initial setting for reading the recorded information. FIG. 9 shows the flow of the initial setting subroutine of the prefetch function by the recorded information reproducing apparatus of the present invention. FIG. 9 shows a flow on the side of the host computer 1 executed in the configuration of FIG. 1. First, the CPU 11 of the host computer 1
Sends the prefetch OFF command as shown in FIG. 8 to the disc drive device 2 which is the recording information reproducing device (step S1). The disk drive device 2 fetches the received prefetching OFF command in the RAM 23 and sets the parameters for not performing prefetching. Next, the CPU 11 of the host computer 1 creates a directory #k in which information indicating the arrangement of blocks in the data area and the directory area of the recording disk 27a incorporated in the disk drive device 2 is recorded as shown in FIG. A read command and an address are sent to the disk drive device 2 for reading.

In response to this, the disk drive device 2 reads the contents of the directory #k and sends it to the host computer 1. The CPU 11 of the host computer 1
The contents of the received directory #k are fetched into the register built in the CPU 11 (step S2). Next, the CPU 11 of the host computer 1 sends a read command and an address to the disk drive device 2 in order to read the data #k corresponding to the directory #k.
In response to this, the disk drive device 2 reads the content of the data #k and sends it to the host computer 1 (step S3). Next, the CPU 11 of the host computer 1
Determines whether the arrangement of blocks in the directory area is in the ascending order of addresses according to the contents of the 0th bit shown in FIG. 6 in the contents of the directory #k fetched in the register built in the CPU 11 in step S2. (Step S4). When it is determined in step S4 that the content of the 0th bit is "1", that is, the address is in ascending order,
Whether the CPU 11 of the host computer 1 arranges the blocks in the data area in the ascending order of the address according to the contents of the first bit shown in FIG. 6 among the contents of the directory #k fetched in the register incorporated in the CPU 11 in step S2. It is determined whether or not (step S5).

If it is determined in step S5 that the content of the first bit is "0", that is, the address is not in ascending order,
The CPU 11 of the host computer 1 sets the descending order prefetch command for the data area according to the command format of FIG. 7A (setting the 7th bit to “1” and the 6th bit to “0”) and the command of FIG. 7B. An ascending order prefetch command for the directory area according to the format (7th bit is set to "1" and 6th bit is set to "1") is sent to the disk drive device 2 (step S6).

When it is determined in step S5 that the content of the first bit is "1", that is, the address is in ascending order,
The CPU 11 of the host computer 1 sets the ascending order read-ahead command (setting the 7th bit to "1" and the 6th bit to "1") of the data area according to the command format of FIG. 7A and the command of FIG. 7B. An ascending order prefetch command for the directory area according to the format (7th bit is set to "1" and 6th bit is set to "1") is sent to the disk drive device 2 (step S7).

When it is determined in step S4 that the content of the 0th bit is "0", that is, the address is not in ascending order,
Whether the CPU 11 of the host computer 1 determines whether the arrangement of blocks in the data area is in the ascending order of addresses according to the contents of the first bit shown in FIG. 6 among the contents of the directory #k fetched in the register incorporated in the CPU 11 in step S2. It is determined (step S8).

When it is determined in step S8 that the content of the first bit is "0", that is, the address is not in ascending order, the CPU 11 of the host computer 1 reads the descending order prefetch command of the data area according to the command format of FIG. 7A. (The 7th bit is set to “1” and the 6th bit is set to “0”) and the descending order prefetch command of the directory area according to the command format of FIG. 7B (7th bit is “1”, 6th bit is "Set to" 0 ") is sent to the disk drive device 2 (step S9).

When it is determined in step S8 that the content of the first bit is "1", that is, the address is in ascending order,
The CPU 11 of the host computer 1 sets the ascending order read-ahead command (setting the 7th bit to "1" and the 6th bit to "1") of the data area according to the command format of FIG. 7A and the command of FIG. 7B. A descending order prefetch command for the directory area according to the format (7th bit is set to "1" and 6th bit is set to "0") is sent to the disk drive device 2 (step S10).

As described above, the disk drive device 2 is
The prefetch command sent by any of the above steps 6, 7, 9 and 10 is received and fetched in the RAM 23, and parameters are set in accordance with this prefetch command. FIG. 10 shows a flow chart of reading recorded information by the recorded information reproducing apparatus of the present invention.

The recording information reading flow chart of FIG. 10 is a flow chart on the side of the disk drive device 2 which is executed after completion of the initial setting of FIG. 9. First, the CPU 21 of the disk drive device 2 determines whether or not to perform prefetching. Of the information shown, "0" indicating that prefetching is not executed is stored in the internal register A of the CPU 21 (step S2).
1). Next, the CPU 21 of the disk drive device 2
It is determined whether the read command is supplied from the host computer 1 (step S22). Step S
When it is determined in 22 that the read command is not supplied from the host computer 1, the CPU 21
It is determined whether the content of the internal register A is "1" (step S23). When it is determined in step S23 that the content of the internal register A is not "1", the process returns to step S22 and the above-described operation is repeated. When it is determined in step S22 that the read command is supplied from the host computer 1, the CPU 21 takes in the address supplied at the same time as the read command, and the information designated to be read at this address is stored in the buffer memory 2
4 is stored (step S).
24). In step S24, the buffer memory 24
If it is determined that the block 27 corresponding to this address is not stored, the CPU 21 moves the pickup 27c to the position corresponding to this address (step S25), and the contents of the block corresponding to this address are picked up from the recording disk 27a.
It is read by c and stored in the buffer memory 24 via the modulation / demodulation means 26 and the error correction circuit 25 (step S26).

After the end of step S26, or when it is determined in step S24 that the data is already stored in the buffer memory 24, the CPU 21 executes step S2.
2 reads the contents of the block corresponding to the address supplied from the buffer memory 24, and the host computer 1 through the relay means 28 and the interface bus 3.
Send to. At this time, the CPU 21 causes the buffer memory 24
Among the contents of the blocks stored in, those which have been sent to the host computer 1 are erased (step S2).
7). Next, the CPU 21 stores the prefetch command 7 stored in the RAM 23 in the format shown in FIG.
It is determined from the bit position whether or not the read-ahead function is designated to be ON (step S28). Step S28
If it is determined that the prefetch function is not designated to be ON in step S21, the process returns to step S21 and the above-described operation is repeated. When it is determined in step S28 that the read-ahead function is ON, the CPU 21 determines whether the buffer memory 24 is empty (step S).
29).

When it is determined in step S29 that the buffer memory 24 is not empty, the process returns to step S21. When it is determined in step S29 that the buffer memory 24 is empty, the CPU 21 stores "1" indicating execution of prefetch in the internal register A of the CPU 21 (step S30), and returns to step S22. At this time, if it is determined in step S22 that the read command is not supplied from the host computer 1,
The CPU 21 determines whether or not the content of the internal register A is "1" (step S23). Step S2
When it is determined in 3 that the content of the internal register A is “1”, the CPU 21 stores 6 of the prefetch command stored in the RAM 23 and having the format as shown in FIG.
From the bit number, it is determined whether or not the ascending order of prefetching is designated (step S31). When it is determined in step S31 that the prefetching ascending order is designated,
The CPU 21 moves the pickup 27c in ascending address order by the amount of the prefetch block designated by bits 5 to 0 of the prefetch command having the format shown in FIG. Read, store in buffer memory 24,
When the storage of the number of prefetch blocks is completed, step S2
It returns to 1 (step S32).

When it is determined in step S31 that the pre-reading ascending order is not designated, the CPU 21 moves the pickup 27c to the block position immediately before the block indicated by the address supplied in step S22, and moves the pickup 27c to this block. Read the contents. When the reading is completed, the CPU 21 moves the pickup 27c in the address descending direction, brings the pickup 27c to the head of the block recorded before the block where the reading is completed, and starts the reading. The above operation is repeated for the number of read-ahead blocks specified in the read-ahead command having the format shown in FIG.
Each is stored in the buffer memory 24 (step S3
3). In this case, the pickup 27c may be moved in the address descending direction at a time to the beginning of the pre-read designation area, and then the contents of each block may be sequentially read in the address ascending direction. After the end of step S33, the process returns to step S21 and waits for a read command.

FIG. 11 shows an example of reading the directories # 3 to # 4 in FIG. 2B according to the flow chart of FIG. In the operation of FIG. 11, the initial setting has been completed in advance according to the initial setting flowchart shown in FIG.
It is assumed to be stored in a predetermined address of AM23.

First, when the supply of the read command and the address for reading the directory # 3 is confirmed from the host computer 1 in step S22, whether the contents of this address, that is, the contents of the directory # 3 are stored in the buffer memory 24 or not. The determination is made in step S24. Since the contents of the directory # 3 are not stored in the buffer memory 24, by step S25,
The pickup 27c is moved to the position corresponding to this address. Next, in step S26, directory # 3
Is taken in, and the contents of directory # 3 are sent to the host computer 1 in step S27. Next, according to step S29, since data is not yet stored in the buffer memory 24, step S30,
Via step S22 and step S23, step S
Move to 31. When it is confirmed in step S31 that the blocks are recorded in the descending order of address in the directory area, prefetching in descending order of address is executed in step S33, and the contents of the directories # 4 and # 5 are fetched and stored in the buffer memory 24. .

Next, through step S21, step S
It becomes a waiting state for the read command by 22. When the supply of the read command is confirmed from the host computer 1 in step S22, it is determined whether or not the content of the address (address for reading the directory # 4) supplied at the same time as the read command is stored in the buffer memory 24. The determination is made in step S24. Since the contents of the directory # 4 are stored in the buffer memory 24, the step S27 is directly executed and the buffer memory 2
The contents of the directory # 4 stored in No. 4 are sent to the host computer 1. Next, according to step S29, since the data (contents of the preread directory # 5) is stored in the buffer memory 24, step S29 is performed.
Via S21, the read command is waited in step S22. When the supply of the read command is confirmed from the host computer 1 in step S22,
It is determined in step S24 whether or not the contents of the address (address for reading the directory # 5) supplied at the same time as this read command are stored in the buffer memory 24.
Done in. Since the contents of the directory # 5 are stored in the buffer memory 24, the step S27 is directly executed to send the contents of the directory # 5 stored in the buffer memory 24 to the host computer 1.

FIG. 12 shows another example of reading the directories # 3 to # 4 in FIG. 2B according to the flowchart of FIG. 10 described above. First, in step S22, when the supply of the read command and the address for reading the directory # 3 is confirmed from the host computer 1, it is determined whether the content of this address, that is, the content of the directory # 3 is stored in the buffer memory 24. Is performed in step S24. Since the contents of the directory # 3 are not stored in the buffer memory 24, the pickup 27c is moved to the position corresponding to this address in step S25. Next, step S
The contents of the directory # 3 are fetched by 26, and the contents of the directory # 3 are sent to the host computer 1 by step S27. Next, according to step S29, since data is not yet stored in the buffer memory 24, the process proceeds to step S31 via steps S30, S22 and S23. Step S3
When it is confirmed that the blocks are recorded in descending order of address in the directory area in step 1, step S33 is performed.
The address descending prefetch is executed by. At this time, the pickup 27c is moved in the address descending direction at a time to the beginning of the preread-designated area directory # 5, and then in the address ascending direction, the directories # 5 and
The contents of each block are fetched in the order of 4 and stored in the buffer memory 24.

Next, through step S21, step S
It becomes a waiting state for the read command by 22. When the supply of the read command is confirmed from the host computer 1 in step S22, it is determined whether or not the content of the address (address for reading the directory # 4) supplied at the same time as the read command is stored in the buffer memory 24. The determination is made in step S24. Since the contents of the directory # 4 are stored in the buffer memory 24, the step S27 is directly executed and the buffer memory 2
The contents of the directory # 4 stored in No. 4 are sent to the host computer 1. Next, according to step S29, since the data (contents of the preread directory # 5) is stored in the buffer memory 24, step S29 is performed.
Via S21, the read command is waited in step S22. When the supply of the read command is confirmed from the host computer 1 in step S22,
It is determined in step S24 whether or not the contents of the address (address for reading the directory # 5) supplied at the same time as this read command are stored in the buffer memory 24.
Done in. Since the contents of the directory # 5 are stored in the buffer memory 24, the step S27 is directly executed to send the contents of the directory # 5 stored in the buffer memory 24 to the host computer 1.

As described above, according to the recorded information reproducing apparatus of the present invention, even in the reading of the directory area in which the blocks are recorded in the descending order of the addresses, the blocks are read in the descending order of the addresses and the pre-reading is performed, which is wasteful. High-speed reading is performed without pre-reading. In the read-ahead setting command format of FIG. 7, the 7th bit is a bit related to ON / OFF of the read-ahead and the 6th bit is a bit related to the direction of the read-ahead, but it can be set by other methods.

For example, 0 to 7 bits are allotted as the number of read-ahead blocks in the 2's complement representation. When all of the 0 to 7 bits are "0", the read-ahead block is set to OFF, and the number of read-ahead blocks consisting of 0 to 7 bits is negative. When the number of read-ahead blocks is plus, the setting command format is such that the read-ahead is performed in the ascending order of addresses.

[0042]

As described above, in the recorded information reproducing apparatus of the present invention, in one arbitrary block of the directory area of the recording medium, the arrangement of the respective blocks of the data area and the directory area of the recording medium is the address. This recording format information is read from the recording medium on which the recording format information indicating the ascending order or the address descending order is recorded, and whether the arrangement of each block of the data area and the directory area of the recording medium is the address ascending order or the address. Whether the address is in descending order is detected, and either address ascending order prefetching or address descending order prefetching is selected based on the detection result and the read address to perform prefetching.

Therefore, according to the present invention, in the reading in any of the area in which the blocks are recorded in the ascending order of addresses and the area in which the blocks are recorded in the descending order of addresses, the pre-reading of the blocks according to the recording order is performed. Since it can be performed, high-speed reading is performed without unnecessary pre-reading.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a host computer and a recorded information reproducing apparatus.

FIG. 2 is a configuration diagram of a recording medium.

FIG. 3 is a diagram showing a read-ahead operation of recorded information in a recorded-information reproducing apparatus.

FIG. 4 is a conventional prefetch setting command.

FIG. 5 is a diagram showing a read-ahead operation of a directory area in a conventional recorded information reproducing apparatus.

FIG. 6 is a directory format diagram in the recording medium of the present invention.

FIG. 7 is a format diagram of a prefetch setting command in the recorded information reproducing apparatus of the present invention.

FIG. 8 is a diagram showing an embodiment of a prefetch setting command in the recorded information reproducing apparatus of the present invention.

FIG. 9 is a flowchart of a read-ahead initialization subroutine in the recorded information reproducing apparatus according to the present invention.

FIG. 10 is a read-ahead read flowchart in the recorded information reproducing apparatus of the present invention.

FIG. 11 is a diagram showing an example of a descending prefetch operation in the recorded information reproducing apparatus of the present invention.

FIG. 12 is a diagram showing another embodiment of the descending prefetch operation in the recorded information reproducing apparatus of the present invention.

[Explanation of symbols for main parts]

 2 Recorded information reproducing device 27a Recording disk

Claims (1)

[Claims] 1. A data area in which information data is divided and recorded in each block and a directory area in which management information is divided and recorded in each block, and each of the data area or the directory area is recorded. A recording information reproducing apparatus for a recording medium in which blocks are recorded in ascending order of addresses or in descending order of addresses, and whether the addresses of the blocks of the data area or the directory area recorded from the recording medium are recorded in ascending order. Recording format detecting means for detecting whether or not the data is recorded in descending order, and prefetching information data or management information from the recording medium in accordance with a read command and a read address from a block corresponding to the read address to a block of a predetermined number ahead. Pre-reading means for reading the recorded information, the read address and the read address Recorded information reproducing apparatus characterized by having a look-ahead direction control means for switching control of the read-ahead direction of the record information read-ahead means address ascending direction or address descending direction according to recording format information.