JPH0540663A - Cd-rom emulator - Google Patents

Abstract

PURPOSE:To eliminate the timing problem caused by the difference of data reading speeds between a CD-ROM serving as an actual target and a magnetic disk of an emulator in regard to the CD-ROM emulator consisting of a magnetic disk used for development of the application software of a CD-ROM base. CONSTITUTION:Both invalid and valid data are written into each area of a CD-ROM 1 and the areas of a magnetic disk 2 corresponding to those areas of the CD-ROM 1 respectively. The read command produced to a CD-ROM driver 3 from a host device 10 is intercepted by a command interpreter 4. Then this intercepted command is converted into a read command that is addressed to a magnetic disk driver 5 and transferred to this driver. Based on this command, the valid data read out of the disk 2 are transferred to the device 10 synchronously with the invalid data outputted from the driver 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to game software such as C
The present invention relates to a CD-ROM emulator used for developing D-ROM based application software.

[0002]

2. Description of the Related Art Recently, recording / recording of AV data etc. has been accompanied by the sophistication of application software such as game software.
The amount of data to be played back is increasing, which is why AV
Large-capacity CD as a recording medium for data and programs
-ROM is being used. This CD
Since the ROM-ROM itself is a non-writable recording medium, when developing a CD-ROM-based application software that uses this as a data recording medium, an appropriate data read-out operation from the CD-ROM is simulated. An emulator for CD-ROM is required. As such an emulator for CD-ROM, a combination of a magnetic disk driver and a command interpreter section for operating the same has been conventionally used widely.

[0003]

However, since the data reading speed from the CD-ROM is much slower than that from the magnetic disk, the application software developed by using the CD-ROM emulator using the magnetic disk is the CD-ROM. When actually operating for a WORM that can be written only once, it often does not operate normally at a critical timing portion. Therefore, the application software needs to be reworked a number of times, and there is a problem that it takes a lot of labor and time to develop it.

[0004]

The CD-ROM emulator of the present invention is effective for a CD-ROM in which dummy invalid data is written in each area and a corresponding area corresponding to each area of this CD-ROM. A magnetic disk on which data is written and a CD-RO according to a read command from the host device
A CD-ROM driver for reading invalid data from each area of M and transferring it to a host device, and a CD-ROM from the host device
A command interpreter unit that intercepts the read command issued to the driver, converts it into a read command of valid data from the corresponding area of the magnetic disk, and transfers it to the magnetic disk driver, and the magnetic disk according to the read command received from this command interpreter. A magnetic disk driver that reads and outputs valid data from each area, and a synchronous transfer circuit that transfers the valid data output from the magnetic disk driver to a host device in synchronization with the reading of invalid data from the CD-ROM driver. Is equipped with.

That is, according to the CD-ROM emulator of the present invention, the data read from the magnetic disk is stored in the CD.
Since the data can be transferred to the host device in synchronization with the read timing of the corresponding data from the ROM driver, the conventional problems caused by the difference in the data read speed from the magnetic disk and the CD-ROM are eliminated. It

[0006]

1 is a block diagram showing the configuration of a CD-ROM emulator according to an embodiment of the present invention together with the relationship with a computer 10 which is a higher-level device, and 1 is a CD-RO.
M, 2 are magnetic disks, 3 are CD-ROM drivers, 4
Is a command interpreter unit, 5 is a magnetic disk driver, 6 is a data buffer, 7 is a shift register, 8 and 9
Is a bus.

The computer 10 imitates a target computer that executes developed application software, and the CD-ROM driver 3 imitates a target CD-ROM driver that is connected to the target computer. It is a thing.

According to the application software under development executed by the computer 10, AV data or the like is read from the CD-ROM 1 via the bus 8 and the CD-ROM driver 3. AV read by this computer 10
The data and the like are previously stored in the CD-ROM 1 as dummy invalid data composed of a specific bit pattern such as all “0”.
Of the CD-ROM 1 are recorded in the corresponding areas of the magnetic disk 2 corresponding to the respective areas of the CD-ROM 1 in advance as effective data. This valid data is transferred to the disk controller 5 as write data from a downloader (not shown) or the like and written in the corresponding area of the magnetic disk 2.

When the computer 10 outputs a read command addressed to the CD-ROM driver 3 to the bus 8 according to application software under development, this read command is sent via the selector 8 to the CD-ROM driver 3
Transferred to. CD-RO that received this read command
The M driver 3 uses the CD specified by this read command.
-Invalid data is read from a predetermined area of the ROM 1 and placed on the bus 8.

In parallel with the above-mentioned data read / transfer operation by the CD-ROM driver 3, the data read / transfer operation by the CD-ROM emulator is performed. That is, the command interpreter unit 4 intercepts the read command addressed to the CD-ROM driver 3 appearing on the bus 8, converts it into a read command addressed to the disk controller 5, and transfers the read command to the disk controller 5. The disk controller 5 receiving this read command reads valid data from the corresponding area of the magnetic disk 2 and transfers it to the shift register 7 via the data buffer 6.

As described above, the reading of invalid data from the CD-ROM 1 and the reading of valid data from the magnetic disk 2 are performed in parallel, but the latter reading is performed faster than the former. By the time invalid data appears on the bus 8, the holding of valid data in the shift register 7 has already been completed. The valid data held in the shift register 7 is transferred to the computer 10 via the bus 9 in synchronization with the data strobe signal indicating that the transfer data appears on the bus 8.

As a result, the computer 10 can receive the valid data read from the magnetic disk 2 at the transfer timing of the invalid data from the CD-ROM driver 1.

The computer 10 receives valid data on the bus 9 instead of invalid data on the bus 8 and sends it to the CD.
-Process as read data transferred from the ROM driver 3.

In the above, the configuration in which the computer 10 selects the valid data appearing on the bus 9 instead of the invalid data appearing on the bus 8 has been illustrated. However, buses 8 and 9
A selector that selectively connects one side to the computer 10 is installed, and the selection state of this selector is set to the computer 10
Alternatively, it is also possible to adopt a configuration in which only valid data is selectively transferred to the computer 10 by being controlled by the command interpreter unit 4.

[0015]

As described in detail above, the C of the present invention
According to the D-ROM emulator, the data read from the magnetic disk can be transferred to the higher-level device in synchronization with the read timing of the corresponding data from the CD-ROM driver. The conventional problems caused by the difference in the data read speed of the above are solved. As a result, the labor and time required for developing the application software can be significantly reduced.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a CD-ROM emulator according to an embodiment of the present invention together with a relation with a computer as a host device.

[Explanation of symbols]

 1 CD-ROM 2 magnetic disk 3 CD-ROM driver 4 command interpreter 5 disk controller 6 data buffer 7 shift register 8, 9 bus

Claims (1)

[Claims] 1. A CD-ROM in which dummy invalid data is written in each area, a magnetic disk in which valid data is written in a corresponding area corresponding to each area of the CD-ROM, and a host device. C, which reads invalid data from each area of the CD-ROM according to a read command from the C-ROM and transfers it to the host device.
A D-ROM driver and a command interpreter that intercepts a read command issued from the host device to the CD-ROM driver, converts the read command into valid data read command from a corresponding area of the magnetic disk, and transfers the read command to the magnetic disk driver. Section, a magnetic disk driver for reading and outputting valid data from each area of the magnetic disk in accordance with a read command received from the command interpreter, and valid data output from the magnetic disk driver is invalidated by the CD-ROM driver. A CD-ROM emulator, comprising: a synchronization transfer circuit that transfers data to the higher-level device in synchronization with data reading.