JPH08339267A - External storage device for computer - Google Patents

Abstract

PURPOSE: To eliminate useless compressed data read and to directly read the compressed data of an optional address by providing a data expansion means provided with an offset address register for skipping read. CONSTITUTION: In this external storage device 1 provided with a compressed data expansion mechanism, by setting the position (address) of the data to be obtained in an offset register, the compressed data expansion mechanism 3 repeats the read and expansion of the compressed data from a ROM 11, cancels unrequired data and performs setting in a read data register from the data of the requested position. During the processing of cancelling the unrequired data, indication is performed in a status register as a state in which read data are not prepared similarly to the time while expanding the compressed data and a CPU 7 judges whether or not the read register can be read by reading the status register.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an external storage device used in a computer game machine using a non-volatile semiconductor memory such as a ROM cartridge.

[0002]

2. Description of the Related Art The basic structure of a computer game machine is a device for inputting data, a device for outputting data, and a computer main body, as in a general computer. The external storage device of the computer game machine is a CD-
ROMs, ROM cartridges, etc. are used. These are sold for each game software.

For example, a ROM mounted in an external storage device cannot be written, but a general external storage device has a writable memory (RAM) having a battery backup mechanism as shown in FIG. It is built in, and is devised so that it can memorize the state in the middle of the game and the password for each player.

FIG. 3 shows an example of the basic hardware configuration of the computer game machine body. The CPU is a central processing unit, which is the core of the game machine. The programs and data stored in the external storage device are subjected to processing such as program execution, data processing, and transfer by CPU analysis. Image data read from an external storage device or image data created by a program is sent to a VDC (video display controller) and processed (defined) into image data that can be displayed on a display.

Data processed by VDC is temporarily stored in VRAM. The data defined by VDC and stored in the VRAM is divided into background (background image) and sprite (protagonist of motion, etc.), and information such as its display pattern, display position on the display, and display color is added.

A VCE (video color encoder) converts a digital color image signal sent from VDC through a video output port into a CRT analog RGB signal and a video color signal based on color palette information stored in the VCE. , Output to an external video device.

On the other hand, sound information such as music and onomatopoeia analyzed by the CPU is a sound effect integrated with an image by a function of a stereo circuit configuration, a noise generation circuit, a low frequency generation circuit, etc. by a PSG (program sound generator). Is output to the speaker.

The game machine handles image data in which animations and photographs are taken. In particular, games incorporating movie images and video natural images have recently come into the limelight. Also animation
More and more colorful images are being handled.

In many cases, a computer game machine handles image data including an animation or a photograph. In particular, games incorporating movie images and video natural images have recently come into the limelight. Image data, unlike text data, requires a large amount of memory. The closer it is to a natural picture, the more memory it requires. Also, animations are becoming more multicolored and more precise.

The finer the image to be handled and the more colors it has, the larger the image data amount becomes. Therefore, the external storage device that provides the game is required to be a large-capacity storage medium. However, since increasing the capacity of the storage medium increases the cost, it is difficult to simply apply the same to a computer game machine that requires low cost. Therefore, a commonly used method is data compression. There are various methods for compressing data.

By compressing the data, the memory capacity of the external storage medium for recording the data can be saved, but the compressed data cannot be used as it is. When the computer game machine reads the compressed data, it must revert to the original format of the data. This "returning to the original data" is called data expansion, and in a computer-computer game machine using a conventional external storage device, this data expansion is performed by the CPU of the game machine body.

FIG. 4 is an explanatory diagram of a computer game machine using an external storage device having a non-volatile semiconductor memory. The image control means 9 is VDC, VCE, VRAM shown in FIG.
Equivalent to. The voice control means 10 corresponds to the PSG in FIG. The ROM 2 stores programs and data. First, when the power is turned on, the CPU 7 starts reading the program from a certain fixed address on the ROM 2 and analyzes and executes the program according to the logic of the program.

When there is a data read command in the program, the CPU 7 reads the data in the ROM 2 and RA
The data is expanded to M8, or depending on the type of data, the data is directly transferred to the image control means or the audio control means. These image control means and audio control means also operate under the control of the CPU 7.

[0014]

In the conventional computer game machine, if the data in the external storage device contains compressed data, it cannot be used even if it is sent directly to the image control means 9 or the audio control means 10. First, the compressed data is once read into the RAM 8 and then decompressed by the CPU 7 to restore the original raw data. With such compressed data, the CPU 7 had to spend processing time to decompress the data.

As described above, the conventional external storage device such as the ROM cartridge is merely a storage medium for programs and data. When decompressing the compressed data, the CPU of the computer game console must perform the expansion.
The CPU was overloaded.

FIG. 5 shows an example of the structure of a conventional compressed file. The program is stored in the non-compressed data format at the beginning of the ROM, and the compressed data is stored after that. Since the compression rate of compressed data differs depending on the content of the data, the size of each data differs as shown in the figure.

The present invention seeks a solution in interlaced reading of compressed data. Interlaced reading is reading of compressed data at a position distant from the reference compressed data address. The conventional method of interlaced reading is to sequentially read from the starting address of the compressed data as a reference to the requested data, and determine whether or not it is the desired data.
The PU, that is, the program, judged and read.

For example, in the example of the compressed data structure of FIG. 5, the head addresses of the compressed data 1, 2, 3, ... Can be accessed directly, but the contents (intermediate data) of each compressed data are accessed. It was necessary to read the compressed data in order from the top address of the compressed data, and proceed to the target data. For this,
Wasted processing such as reading, decompression, and discarding of compressed data was performed.

It is an object of the present invention to provide a method for directly reading compressed data at an arbitrary address in skipped reading of compressed data, which eliminates the useless reading of compressed data which has been performed by the conventional method. .

[0020]

In order to solve the above problems, the present invention uses an external storage device having a compressed data decompression mechanism as shown in FIG. 6 to perform read processing and management of compressed data. It is something to do.

Further, the compressed data decompression mechanism performs decompression transfer of the compressed data, so that the CPU of the computer game machine
Can eliminate the need to spend time on this process. However, although it was possible to solve the problem of reading compressed data in units of compressed data, in order to read the compressed data at each arbitrary position, it is not possible to sequentially read the data up to the position of the requested compressed data, The CPU load for decompressing unnecessary compressed data and determining whether it is necessary or not until the arrival of the data still remains.

The conventional problem is that there is no means for designating an arbitrary address. Therefore, in the present invention,
Introducing an offset register to the compressed data decompression mechanism,
The method of calculating the absolute address by the offset (relative address from the start address) of the compressed data corresponding to the data number is incorporated. As a result, the desired compressed data can be directly accessed by the offset register.

[0023]

EXAMPLE An example of performing interlaced read processing of compressed data based on the data of FIG. 7 will be described by comparing the present invention with the conventional one. Original data to be compressed in FIG. 7 (uncompressed data)
The compressed results of compressed data are the same depending on the data compression tool used, both in the present invention and in the prior art. If the offset register of the present invention is not used, in order to read the compressed data at a position away from the start address, it is necessary to read from the start in order and follow the target data. This is shown in FIG.

In FIG. 7, the left side of the figure is the original data to be compressed,
The figure shows the compressed data obtained by compressing it, and the figure on the right shows the state when the compressed data is read and restored (the pattern is the same as the figure on the left). Now, the 3rd and 4th data from the start address are required. In the case of non-compressed data, since the length of each data is fixed, the address from the beginning can be simply obtained. For example, if the read address is "start address + 0040" and the ROM is read, the third data can be read directly.

However, since the data lengths of compressed data are not constant, the target data position cannot be known. Therefore, it is necessary to read the compressed data sequentially from the head address, decompress the compressed data, restore the original data, and determine whether or not the data is the requested data. Therefore, in the example of FIG. 8, the two character data from the top are not necessary, but read and decompressed, and then the CPU discards them as unnecessary data.

Particularly in the prior art, since the CPU of the computer game machine has to perform a series of operations of reading, decompressing and discarding the compressed data, CP
The load on U was large, which affected the processing speed of the game. In addition, this series of processes must be described by a program, which has a bad influence on the program development efficiency.

FIG. 8 is a flow chart of the interlaced read processing corresponding to FIG. In the figure, the requested data is expanded in the loop (1). As a result of this expansion, the position of the data to be obtained is known for the first time, so the data address to be obtained is calculated after the loop of (1), and the "required data transfer process" is performed.

FIG. 9 is an outline of the interlaced read processing corresponding to FIG. 7 using the offset register of the present invention. The left and right of FIG. 9 are the same as those of FIG. 7, but the picture on the right shows that the data requested directly was obtained.

In the external storage device equipped with the compressed data decompression mechanism of the present invention, the compressed data decompression mechanism repeats reading and decompression of compressed data from the ROM by setting the position (address) of the desired data in the offset register. , Unnecessary data is discarded, and the data at the requested position is set in the read data register. During the process of discarding the unnecessary data, the status register indicates that the read data is not prepared as in the case of expanding the compressed data, and the CPU can read the read register by reading this register. Determine if possible.

FIG. 1 is a flow chart of the data read processing described above. In addition, the CPU of the computer game machine performs the determination of "has the necessary amount of decompressed data been acquired?" Performed in the loop of (2).

[0031]

In the conventional home game machine, the decompression of the compressed data is performed by software. For this reason, in the conventional system, in order to perform interlaced reading of compressed data, it is necessary to read extra data in order from the start address in order to search for the desired compressed data.
Furthermore, since the CPU determines and discards unnecessary compressed data, the processing speed is reduced. These processes take a lot of dead time for the CPU, which adversely affects the processing speed of the game software.

On the other hand, if the offset register of the present invention is used, the target compressed data can be directly read out at any position, and the load on the CPU can be reduced, and at the same time,
The time to read compressed data can be shortened. Also, the program description becomes simpler than the conventional method. As a result, the present invention makes it possible to improve processing efficiency and program development efficiency.

[Brief description of drawings]

FIG. 1 is a flow chart of interlaced read processing of compressed data performed by an external storage device of the present invention.

FIG. 2 is an explanatory diagram of an external storage device with a battery backup.

FIG. 3 is a block diagram of a computer game machine.

FIG. 4 is an explanatory diagram of a configuration of a conventional external storage device and a computer game machine.

FIG. 5 is a structural example of a conventional compressed file.

FIG. 6 is an explanatory diagram of a compressed data decompression mechanism of the present invention.

FIG. 7 is a conceptual diagram of conventional interlaced read processing.

FIG. 8 is a flowchart of a conventional interlaced read process of compressed data.

FIG. 9 is a conceptual diagram of interlaced read processing of the present invention.

[Explanation of symbols]

 1 External Storage Device 2 ROM 3 Compressed Data Decompression Mechanism 4 Compressed Data ROM Address Generation Mechanism 5 ROM Bank Switching Mechanism 6 Computer Game Machine Main Body 7 CPU 8 RAM 9 Image Control Means 10 Voice Control Means 11 Compressed Data Storage ROM 12 For Program Storage ROM 13 ROM interface block 14 CPU interface block 15 Compressed data decompression mechanism

Claims (1)

[Claims] 1. An external storage device for a computer having a nonvolatile semiconductor memory for storing data and programs and a mechanism for decompressing compressed data on the memory, comprising data decompression means having an offset address register for skipping reading. An external storage device for a computer.