JPH0281122A - Data reading method - Google Patents

Abstract

PURPOSE:To quickly cope with an external instruction by reading directly the data equal to (n) sectors out of a memory with no access given to a disk in case a reading instruction is received for the data equal to (n) sectors following the data equal to (m) sectors. CONSTITUTION:The data is written into a memory 6 with a reading instruction and at the same time the sector number of the data is written into a memory control table 8. Thus the data equal to (m) sectors (m>=1) is read out of the k-th sector with an external reading instruction. In this respect, the variable (j) of a program of a CPU 9 is set at (k). Then it is checked whether the sector number of j = k is written into the table 8 or not, that is, whether this sector number is read out before or not. If so, the data on the sector number is read out of the memory 6 and sent to the outside. Thus it is possible to know via the table 8 that the data if once read out of a disk 5 is written into the memory 6. Then the data c an be quickly read out of the memory 6 with no access given to the disk 5.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a data reading method in which data is read from a recorded medium such as a disk in response to an external command, temporarily stored in a memory, and read from the memory and transferred to the outside.

When the operations of reading data from a disk, writing it to memory, reading it from there, and transferring it to an external device are controlled by a microcomputer, etc., as described above, the microcomputer operates within a short time after receiving an external command. It is desirable to transfer data externally.

Conventional technology FIG. 5 shows a block diagram of an example of a conventional device.

In the same figure, when an external command signal is input to a terminal 1, a CP (J3) consisting of a microcomputer, etc. of a disk control device 2 receives this and issues a read command to a disk driver 4, and the disk driver 4 receives, for example, program data. etc. are recorded from the disk 5, and the disk control device 2 writes this to the memory 6.The CPU 3 performs processing such as error correction on the data written to the memory 6 and transfers the data. and take it out from terminal 7.

Problems to be Solved by the Invention In general, the time required for the operation of the CPLJ3 to receive an external command, access the disk 5, and read data from it is extremely short in terms of the overall operation. The disk driver 4 does not operate at any other time, and the time is wasted. On the other hand, from the user's point of view, during normal use, the user mostly accesses only the program data in a specific portion of the disk 5, and often concentrates on reading the specific program data. In other words, if there is an instruction to read m sectors worth of data from the disk 5, the next n sectors following this m sector will be read.
There is a high probability that a sector's worth of data will be read.

In this case, in the conventional device, even if the data is the same as previously accessed, each time a read command is issued to the disk driver 4, it is written into the memory 6, and the data is transferred by reading from there. Therefore, the conventional device has the problem that it takes time to read and transfer data from an external command, making it impossible to quickly control reading.

The present invention uses time other than the disk access time as described in the previous 2 to read data following the read data of consecutive sector numbers by an external command from the disk and write it into the memory, and then the read command is executed. It is an object of the present invention to provide a data reading method that allows data to be read out quickly from a memory when it is received, and that allows reading control to be performed quickly in response to an external command.

Means for Solving the Problems According to the present invention, when there is a data read command for m sectors with consecutive sector numbers (m≧1), the data for the m sectors is read and transferred, while the data for the m sectors are read and transferred. If the next n sectors worth of data subsequent to the data for the previous n sectors have not been written in the storage means, means for reading the n sectors worth of data from the recording medium and writing it into the recording means; When there is a data read command, the data storage means reads and transfers the data for the n sectors from the storage means.

In the present invention, when there is a read command for consecutive m sectors, data for the next n sectors following the data for m sectors is stored in the storage means, and the data for n sectors is read out. When a command is issued, data for n sectors is read and transferred from the storage means. Generally, after m sectors' worth of data is read, subsequent n sectors' worth of data is often read. According to the present invention, when there is a data read command for n sectors, this n sector's data is read. There is no need to read out the data from the disk,
It can be read immediately from the storage means and can quickly respond to external commands.

Embodiment FIG. 1 shows a block diagram illustrating an embodiment of the method of the present invention, in which the same numbers as in FIG. 5 are given to the same -J#tli portions. In the figure, 8 is the memory il! This is a table in which data for each sector on the disk 5 that has been read from the disk 5 and written to each page of the memory 6 is registered as a sector number in association with that page. 9
is a CPLJ, which is provided with a writing means 9a and a reading means 9b, and operates according to the chart 70 shown in FIGS. 2 and 3. Memory 6, CPU 9. Memory management 1-
The pull 8 constitutes a disk control device 1o.

Next, the operation of the present invention will be explained.

The CPU 9 shown in FIG. 1 monitors the disk driver 4 to determine whether or not the disk 5 is installed (step 51 in FIG. 2). If it is not installed, it repeats step 50, and if it is installed, it manages the memory. Table 8 is all cleared, that is, all XX (zero) are written (step 52).

Thereafter, it is determined whether or not there is an external command to read data from a certain sector from the disk 5 (step 53). If there is a read command, the reading means 9b reads out predetermined data from the memory 6, while the self-programming means 9a reads data from that sector. data is written in the memory 6 sequentially from O page, and the sector number is incremented to the page of the memory management table 8 corresponding to the memory 6 in which the data of the sector is written (step 54). This step 52 and 53
This is continued until it is determined that the disk 5 has been ejected from the disk driver 4, and once the disk 5 has been ejected, the process returns to step 50 (step 55).

Details of steps 53 and 54 above are shown in FIG.

There is an external command to read data with consecutive sector numbers on the disk 5 (step 101 in FIG. 3), and the disk 5
Predetermined data is read from and written into the memory 6. If there is no read command, step 101 is repeated. When there is a read command and data is written into the memory, at the same time, the sector number corresponding to the page written to the memory 6 is written in the memory management table 8 as shown in FIG.

For example, sector number 334 is written to page O, sector number 335 is written to page 1, etc., but this means that the program data of the 334th sector on the disk 5 is written to the part corresponding to page O of the memory 6, and the program data of the 334th sector on the disk 5 is written. This shows that program data of the 335th sector on the disk 5, . . . has been written in the portion corresponding to page 1. In the case of this embodiment, data for 100 sectors can be written (
100 pages).

As mentioned above, if there is a read command and the data is written to the memory 6 and the sector number of the data is stored in the memory management table 8 at the same time, the external read command will write data for m (m≧1) sectors from the first sector. CPU as readout
The variable j of the program No. 9 is set to k (step 102 in FIG. 3). Next, it is determined whether or not the σ sector number is written at j− in the memory management table 8 (whether the sector number at j= has been read before). Step 103>, 1! If there is, the data of that sector number is read from the memory 6 and transferred to the outside (step 104).
). In other words, if you look at the memory management table 8, you can see that if the data has been read once from the disk 5, it has been written to the memory 6, so you can quickly read it from the memory 6 without having to go through the trouble of accessing the disk 5 as in the conventional example. I can put it out.

When the reading of a predetermined sector from the memory 6 is completed, j=j
+1 (step 108).

If the sector number J= is not listed in the memory management table 8, it is determined whether there is an empty (XX) page in the memory management table 8 (step 105), and if there is an empty page, the predetermined sector that has been commanded to be read is read. reads the data from the disk 5 and stores it in the empty page of the memory 6,
The data is read from here and transferred, and the sector number of the data just read from the memory 6 is written in the empty page of the memory management table 8 (step 101). When reading the data and writing the sector number of the data is completed, it is set to j−j+1 (step 108).

On the other hand, if there are no free pages in memory management table 8,
At the same time as reading data from the disk 5 and transferring it, a new sector number of the data is added to the oldest read page in the memory management table 8 (since time has elapsed, the probability of needing to read it again is low). (rewrite) (step 106) 1. Let j=j-1 (
Step 108). The above steps 103 to 108 are repeated for m sectors (step 109).

Next, it is determined whether the number of sectors m for which the read command has just been executed is smaller than the maximum number of sectors mo (which may be infinite) (a constant) that can be stored in the memory management table 8 (step 110 in FIG. 3), and m is If m is greater than mo, the process returns to step 101, and if m is less than or equal to mo, j=+m is set (step 111). Step 1
Steps 11 to 117 are almost the same as steps 102 to 109, and the data of 9 minutes of n cells following 9 minutes of m cells with consecutive sector numbers for which the read command was performed (as shown in FIG. 4,
If the 334th to 338th sectors are 9 minutes of m cells, 9 minutes of n cells will be 9 minutes from the 339th sector)
is written into the memory 6, and the sector number of the data is written into the memory management table 8.

In the same way as reading the 9th m cell above, it is determined whether or not the sector number 10m is written in j- in the memory management table 8 (step 112), and if it is already written, the memory 6 is read.
j=j+ without reading and transferring it as data from
1 (step 116).

If not written, there is space in memory management table 8 (XX)
If there is a free page, the data in the predetermined sector that has been commanded to be read is read from the disk 5 and stored in the free page in the memory 6, and the data in the free page in the memory management table 8 is stored. Then, the sector number of the data just loaded into the memory 6 is written (step 115).

When the writing of data and the sector number of the data are completed, it is set to j−j+1 (step 116). On the other hand, if there is no free page in the memory management table 8, the sector number of the data is newly written (rewritten) to the oldest page read in the memory management table 8 (step 114), and j = j + 1 ( Step 116). The above steps 112 to 116 are repeated for m sectors (step 11γ). From (k+m)th sector to (k+m+n-1
) When the data for nine n cells up to the sector has been written to the memory 6, the process returns to step 101.

As mentioned above, when there is a command to continue reading 9 minutes of m cells, if the data for 9 minutes of n cells following that 9 minutes of m cells has not been written to the memory 6, it is read from the disk 5 and stored in the memory. Add meat to Step 6 and prepare. As a result, when there is a read command for 9 n cells, the data can be quickly read from the memory 6 without having to go to the trouble of accessing the disk 5 as in the conventional case. At this time, even if the user concentrates on accessing a specific part of the disk 5, the necessary data (data for 9 m cells and data for 9 subsequent n cells) is always stored in the memory 6. is written, so the processing efficiency of the CPU 9 is improved. Furthermore, only when the read command for 9 m cells is smaller than the above-mentioned mo sector, n
By performing read/write for 9 seconds, it will only work when accessing less than a certain number of sectors (in other words, it will only write an extra n sectors to a small disk with a small number of sectors). ). For a large disk with a large number of sectors in which the ratio of normally accessed sectors is low, other processing can be performed by the amount of writing for nine n cells, and efficiency is improved.

As described in detail, according to the present invention, when there is a command to read data for 9 n cells following 9 m cells,
It is possible to directly read out the data for nine n cells from the storage means necessary to access the disk, and to respond quickly to external commands.

[Brief explanation of the drawing]

FIG. 1 is a block diagram illustrating an embodiment of the method of the present invention;
Fig. 2 is a flowchart of the write operation to the memory management table, Fig. 3 is a flowchart of the data read and automatic write operation to the memory management table, Fig. 4 is a diagram showing the structure of the memory management table, and Fig. 5 is the conventional FIG. 2 is a block diagram of an example of a device. 1... External command input terminal, 4... Disk driver, 5... Disk, 6... Memory, 7... Data output terminal, 8... Memory management table, 9... CP
U, 9a...writing means, 9b...reading means 10
...Disk control device. Patent applicant: Victor Japan Co., Ltd.

Claims (2)

[Claims] (1) In a data reading method in which a predetermined sector of data is read from an existing recording medium on which multiple sectors of data are recorded by an external command, written to a storage means, read from there, and transferred to the outside, the sector number When there is a command to read data for m consecutive sectors (m≧1), the data for the m sectors is read and transferred, while the data for the next n sectors following the data for the m sectors is read and transferred. is not written in the storage means, read the data for the n sectors from the recorded medium and write it in the storage means, and then when a command to read the data for the n sectors is received, the storage means A data reading method characterized by reading and transferring data for the n sectors from the above. (2) When there is a command to read data for m sectors, the operation of writing data for n sectors into the storage means is as follows: (Number m of read commands) 2. The data reading method according to claim 1, wherein the data reading method is performed only when the maximum number of sectors (m_0) is reached.