JPH05298702A - Information memory employing cd-rom - Google Patents

Abstract

PURPOSE:To provide an information memory employing a CD-ROM in which data can be transferred in real time without waiting for rotation even if a CD-ROM drive having a low capacity data buffer memory is employed. CONSTITUTION:The information memory is configured to begin data transfer upon receiving an interruption request from a CD-ROM drive 8, wherein a CD-ROM data buffer area 3 for temporarily storing data read out from the CD-ROM drive 8 is provided on a controller 1 side. The CD-ROM data buffer area 3 is split into a plurality of management units 30, 31, 32, 33, each corresponding to single block of a CD-ROM, configured such that the data can be stored continuously in the head management area 30 following to the end management area 33 wherein a first pointer P1 designates the number of management units for which the data have been stored and a second pointer P2 designates the head management unit in the management units for which the data have been stored.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information storage device using a CD-ROM drive.

[0002]

2. Description of the Related Art An information storage device using a CD as a ROM as a medium for storing information has been put into practical use. In such an information storage device, a CD storing a huge amount of data is stored in a device called a CD-ROM drive, and a control device is connected to the CD-ROM drive to make the information storage device Composed.

By the way, since the rotation control of the CD in the CD-ROM drive is performed at a constant linear velocity called CLV (Constant Linear Velocity), the rotation number of the CD is changed when performing a seek operation on the CD. There is a need to. For this reason CD-R
The OM drive has a long seek time, and access is very slow compared to a storage device such as a fixed magnetic disk. Specifically, for example, the access time of a fixed magnetic disk is several tens of milliseconds, while that of a CD-ROM drive requires several hundreds of milliseconds to several seconds.

Therefore, in an information storage device using a CD-ROM drive, minimizing the number of times of accessing the CD is an important point for high-speed data input / output. For that purpose, it is possible to fetch a large amount of data from the CD-ROM drive to the control device with one access, but there is a limit due to the capacity of the memory provided in the control device or the circuit configuration. There is a limit. Generally, the maximum amount of data that the control device can fetch from the CD-ROM drive at one time is 64 KB.

When the recording mode of the CD-ROM is mode 1, the amount of data per block of CD is 2 KB, and the average data transfer rate is 75 blocks / sec. Therefore,
In order to read data from the CD-ROM drive to the control device in real time, the control device must be configured to read 75 blocks of data from the CD-ROM drive per second.

Considering, for example, the case where the amount of data transferred from the CD-ROM drive to the control device at one time is 64 KB (the data amount of 32 blocks in the CD-ROM), data is continuously recorded on the CD. Even the existing data is divided into two to three times per second and transferred. Therefore, the control device sends commands to the CD-ROM drive two to three times per second. In such a case, the CD-ROM drive side does not need to perform the seek operation because data transfer may be performed from the next address after the data transfer is completed first, but the CD rotates and the target block is the optical head. There is a waiting time (waiting for rotation) to reach the position.
This waiting for rotation may also occur due to a flaw in the CD-ROM disc or the like.

In the CD-ROM drive, the rotation speed of the disc is
Since the rotation waiting time is relatively low at about 200 to 500 rotations / second, the substantial data transfer rate becomes very slow when this rotation waiting time occurs during data transfer. Specifically, the average rotation waiting time is about 66 ms to 150 ms.

Therefore, in order to transfer the data from the CD-ROM drive to the control device without causing a rotation waiting time, the CD-ROM drive normally stores data temporarily. In general, the memory, that is, the buffer memory is provided. Many cds
-In the ROM drive, the memory for such data buffering has a capacity of 64KB.

By the way, in order to provide an information storage device using a CD-ROM drive at a low cost, it is necessary to make the above memory capacity for data buffering as small as possible. Waiting time frequently occurs and the data transfer rate decreases.

[0010]

As described above, the conventional CD is used.
-In the information storage device using the ROM drive, there is a limit in reducing the number of accesses to the CD, and especially when using an inexpensive CD-ROM drive with a small buffer memory capacity, rotation waiting frequently occurs, There is a problem that the actual data transfer rate becomes very slow.

The present invention has been made in view of such circumstances, and is a CD-R having a small data buffer memory capacity.
An object of the present invention is to provide an information storage device using a CD-ROM drive that can transfer data even if an OM drive is used without waiting for rotation.

[0012]

An information storage device using a CD-ROM drive according to the present invention has a control device, a CD-ROM.
CD-ROM when interrupt request is given from drive
A means for starting data transfer from the drive, a first memory area for temporarily storing the data read from the CD-ROM drive in the memory, and a CD-ROM for starting the data transfer
Has a second memory area for storing the address of the CD-ROM, and a third memory area for storing the application program, etc. The management unit is divided into a plurality of management units, and data can be continuously stored in the first management unit after the last management unit, and the number of management units whose data has been stored by the first pointer is It is characterized in that the first management unit of the management units instructed and having completed the data storage is designated by the second pointer.

[0013]

In the information storage device using the CD-ROM drive of the present invention, when the data to be transferred is read by the CD-ROM drive side, when the CD-ROM drive issues an interrupt request to the control device, the data is transferred. The transfer is started, and the transferred data is sequentially stored in each management unit of the first area of the memory.
At this time, data is continuously stored in the management unit at the beginning after the management unit at the end, and the first pointer indicates the number of management units in which the storage of the data is completed. The first management unit of the management units whose data has been stored is designated.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings showing the embodiments.

FIG. 1 is a block diagram showing an embodiment of the configuration of an information storage device using a CD-ROM drive of the present invention.

In FIG. 1, reference numeral 1 indicates a control device, which is connected to a CD-ROM drive 8. The control device 1 is provided with a memory 2 for storing application programs, data, etc. for performing various processes. The capacity of the memory 2 is generally much larger than the capacity of the data buffer in the CD-ROM drive 8.

The memory 2 of the controller 1 has a first memory area (hereinafter referred to as a CD-ROM data buffer area) 3 for temporarily storing the data transferred from the CD-ROM drive 8. And a second memory area for storing the address of the CD-ROM that started the data transfer (hereinafter, CD-ROM
A start address area 4) is provided separately from a third memory area (hereinafter referred to as an application program area) 5 for storing application programs and the like. this is,
This is because the CD-ROM data buffer area 3 and the CD-ROM start address area 4 can be used by a plurality of application programs.

The state of data transfer between the CD-ROM drive 8 and the CD-ROM data buffer area 3 will be described with reference to the timing chart of FIG.

When a read command RC is issued from the control device 1 to the CD-ROM drive 8 via the signal line 9, the CD-ROM drive 8 executes this read command RC to reach the target block of the CD-ROM. Perform a seek operation. Then, when the data is read from the CD and the data for one block can be transferred, the CD-ROM drive 8 causes the control device 1 to transmit via the signal line 6.
An interrupt request is issued to the control device 1 by raising the interrupt request signal IREC output from the control unit 1 from a low level to a high level as shown in FIG. 2 (a).

When the controller 1 detects the rise of the interrupt request signal IREC from the low level to the high level, the controller 1 sends the signal from the CD-ROM drive 8 via the signal line 7 as shown in FIG. Start reading data DATA. On the other hand, the CD-ROM drive 8 returns the interrupt request signal IREQ from the high level to the low level when the controller 1 receives the interrupt request. After that, when the next one block of data can be transferred, the CD-ROM drive 8 sends the interrupt request signal IR.
EC is raised from low level to high level again to request an interrupt to the control device 1 again, and the control device 1 starts data transfer in response thereto. By repeating such a procedure, data is transferred between the CD-ROM drive 8 and the control device 1.

The controller 1 temporarily stores the data read from the CD-ROM drive 8 as described above in the CD-ROM data buffer area 3 of the memory 2. By the way, this CD-ROM
The data buffer area 3 is divided by the capacity corresponding to one block of the CD-ROM for its management. As an example, FIG. 1 shows a case where the CD-ROM data buffer area 3 has a data capacity of four blocks of the CD-ROM, and the 0th area 30, the first area 31, the second area 32, and the 3rd area. It is divided into four areas, area 33. In the following description, the case where the capacity of the CD-ROM data buffer area 3 is 4 blocks will be taken as an example. However, actually, the CD-ROM data buffer area 3
The capacity of can be as large as possible.

The CD-ROM data buffer area 3 is managed by the CD
-The start address of the data stored in the ROM start address area 4 of the CD-ROM and the two pointers P1 and P2 are used. Here, it is assumed that the first pointer P1 indicates the number of memory areas where data storage is completed, and the second pointer P2 indicates the memory area where data storage is started.

Next, data transfer and memory management will be described with reference to the timing chart of FIG. The initial values of the first pointer P1 and the second pointer P2 are both "
It is 0 ".

As shown in FIG. 3 (c), data transfer is started by the interrupt request signal IREQ from the CD-ROM drive 8 as described above, and the data taken into the memory 2 of the control device 1 is first transferred. The data is stored in order from the 0th area 30 of the CD-ROM data buffer area 3. At this time, as shown in Fig. 3 (f), the address of the CD-ROM that started the data transfer is
It is stored in the CD-ROM start address area 4. Also, each time one block of data is transferred, the first pointer P1 is incremented by 1 as shown in FIG. 3 (d). That state is the portion indicated by reference numeral A in FIG.

As shown in FIGS. 3 (a) and 3 (c), data transfer between the CD-ROM drive 8 and the CD-ROM data buffer area 3 of the memory 2 is performed while the application program is being executed. The operation when the application program requests the CD-ROM drive 8 to transfer two blocks of data after two blocks have been executed is the part indicated by reference numeral B in FIG. 3B. ..

If the data targeted by the application program has already been stored in the CD-ROM data buffer area 3 of the control device 1 after the 0th area 30, the data is applied from the CD-ROM data buffer area 3. Data is directly transferred to the program area 5. Since this data transfer is executed in the memory 2, it ends in a very short time, and the influence on the next processing is extremely small. At this time, each time one block of data is transferred, the first pointer P1 is decremented by 1 as shown in FIG. 3 (d), and the first pointer P1 is decremented by 1 as shown in FIGS. 3 (e) and 3 (f). As described above, the transfer start address of the CD-ROM stored in the second pointer P2 and the CD-ROM start address area 4 is incremented by one.

Then, the CD-ROM drive 8 to the control unit 1
Data is subsequently transferred to the CD-ROM data buffer area 3 of the memory 2. However, since the data cannot be transferred from the CD-ROM drive 8 to the CD-ROM data buffer area 3 beyond the capacity of the CD-ROM data buffer area 3, such processing is prohibited. Prohibition of this processing can be realized by managing the first pointer P1. In this example, the CD
Since the capacity of the ROM data buffer area 3 is four blocks of the CD-ROM, the data transfer is stopped when the first pointer P1 is incremented to 4. This is the portion indicated by reference numeral C in FIG. However, if the value of the first pointer P1 is less than 4, in order to effectively use the CD-ROM data buffer area 3, data should be stored next to the 0th area 30 after the third area 33. Is possible.

In the portion indicated by reference numeral D in FIG. 3, the transfer start address requested by the application program is ADR + 3, and the portion of the CD-ROM stored in the CD-ROM start address area 4 is shown. Data transfer start address ADR + 2
Is an example of a case different from. In this case, the number of transfer blocks is 2.

In this case, first, the data up to the transfer start address ADR + 3 requested by the application program is processed as if it has already been transferred to the applicable program area 5. That is, the difference between the transfer start address ADR + 5 of the CD-ROM stored in the CD-ROM start address area 4 and the transfer start address ADR + 2 requested by the application program is calculated, and this difference "1" is calculated. "The first pointer P1 is subtracted, and the second pointer P2 and the value of the CD-ROM start address area 4 are added. Thereafter, the operation as indicated by reference numeral B in FIG. 3 is repeated corresponding to the number of blocks transferred from the CD-ROM data buffer area 3 to the application program area 5. In this way, data transfer between the CD-ROM drive 8 and the CD-ROM data buffer area 3 of the memory 2 is continuously performed.

As shown in FIG. 3, according to the present invention, the interrupt request signal IREQ is generated at the time when the CD-ROM drive 8 becomes ready for data transfer, and the controller 1 causes the CD-ROM drive 8 to operate. Since data is fetched one after another, there is no waiting for rotation. Further, since the application program can be executed during the time other than the interrupt processing, the influence of the data transfer by the interrupt on the processing which the control device 1 should originally execute is reduced.

As described above, in the information storage device using the CD-ROM drive of the present invention, data transfer from the CD-ROM drive 8 to the control device 1 can be performed without causing a rotation waiting time in the CD-ROM drive 8. CD-ROM continuously because it is done
Even if a CD-ROM drive with a small buffer memory capacity is connected to a device that reads and reproduces the data recorded in, for example, a device that reproduces a moving image, natural moving image reproduction is possible.

[0032]

According to the information storage device using the CD-ROM drive of the present invention, even when a CD-ROM drive having a small memory capacity for buffering data is used, the frequency of occurrence of waiting for rotation is high. Since data can be transferred from the CD-ROM drive in an extremely low state in substantially real time, it becomes possible to provide an information storage device using an inexpensive CD-ROM drive.

[Brief description of drawings]

FIG. 1 is a block diagram showing an example of a configuration of an information storage device using a CD-ROM drive.

FIG. 2 is a timing chart showing a state of data transfer between a CD-ROM drive and a CD-ROM data buffer area.

FIG. 3 is a timing chart for explaining data transfer and memory management.

[Explanation of symbols]

 1 Controller 2 Memory 3 CD-ROM Data Buffer Area 4 CD-ROM Start Address Area 5 Applicable Program Area 30 0th Area 31 1st Area 32 2nd Area 33 3rd Area

Claims (1)

[Claims] 1. A CD-ROM drive including a CD-ROM drive for reading data stored in a CD, and a controller having a memory for controlling the CD-ROM drive and storing the data read from the CD-ROM drive. In the information storage device using the above, the control device starts the data transfer from the CD-ROM drive when an interrupt request is given from the CD-ROM drive, and the CD-ROM drive in the memory. A first memory area for temporarily storing the data read from the memory, a second memory area for storing the address of the CD-ROM that started the data transfer, and a third memory area for storing the application program and the like. The first memory area has a capacity corresponding to one block of the CD-ROM as one unit. The management unit is divided into a number of management units, and data can be continuously stored in the first management unit after the last management unit. An information storage device using a CD-ROM drive, characterized in that the first management unit of the management units whose data has been stored is designated by the second pointer.