JP2746978B2 - External storage device with write protection - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to an external storage device with a write protection mechanism.

(Prior Art) Conventionally, data write protection to an external storage device is performed for the entire device and for a partial area.
There is a street. The latter logically defines the data written in the external storage device as a file name, etc., has an unwritable flag in the information group indicating the characteristics of the data, and first, before accessing the data, In this case, the information indicating the characteristic of (1) is read, and if the write-disabled flag is set, the write-inhibit mechanism is provided in the basic software.

(Problems to be Solved by the Invention) According to the above conventional example, the former for the entire device is effective when the entire device is read-only data,
Cannot be used when partial writing is possible. In the latter method of providing a write disable flag in data and controlling by software, the write protection mechanism is insufficient for allowing access to an external storage device at an address on the storage device. And so on.

The present invention has been made in view of the above circumstances, and provides a write protection information setting command in an external storage device, and externally stores write protection information accompanying the command, which masks data in units of write protection target addresses and sectors. It is an object of the present invention to provide an external storage device with a write protection mechanism that protects data writing to a specific address in accordance with the information when the data is stored on the device and data is written to the external storage device.

[Structure of the Invention] (Means for solving the problem) An external storage device with a write protection mechanism of the present invention is connected to a computer main body via a controller, recognizes a command issued from the main body, and a protection information setting command. Then, write protection information for masking data in the unit of a write protection target address and sector that subsequently arrives, and means for writing the information to an external storage device, and when recognizing a write command, comparing with the address information, Means for generating update data based on the protection information when they match.

(Operation) As described above, a means for processing a write protection information setting command is provided in the controller, and an area for storing the write protection information is added to the external storage device, so that the computer main body can send data to the controller. When a write command arrives, writing is prohibited or permitted in sector units within the write protection target address according to a preset write protection target address and write protection information that masks data in sector units within that address. To control the writing of data.

(Example) Hereinafter, an example of the present invention is described using a drawing.

 FIG. 1 is a block diagram showing an embodiment of the present invention.

In the figure, reference numeral 1 denotes a computer body (CPU), which performs arithmetic processing and controls the entire system. Reference numeral 2 denotes a hard disk controller (HDC) which receives a command issued from the CPU 1 and receives a command from the hard disk drive (HDD).
Control. The HDD 3 is an external storage device that stores data. 4 is a floppy disk controller (FDC)
And receives a command from the CPU 1 to control the floppy disk drive (FDD) 5. FDD5 is an external storage device for storing data, like HDD3. Reference numeral 6 denotes an input / output control device for controlling input / output devices other than the file system, such as a display, a keyboard, and a printer (not shown). Reference numeral 8 denotes a random access memory (RAM), which is a medium in which data and programs are temporarily stored.

FIG. 2 is a flowchart showing the operation of the embodiment of the present invention.

In FIG. 2, the step is a step of determining a command sent to the HDC2, and it is determined whether or not this command is a write protection setting command. The step is a step to be processed when the write protection setting command is recognized in the determination of the step. The CPU 1 loads a write protection target address and command information. The steps are
This is a step of storing data in the HDD 3, and the information obtained in the step is written in a write protection information storage area secured on the HDD 3. Steps are commands,
It is determined whether or not the command is a write command. The step is a step of determining a write address, and it is determined whether or not the address is the address obtained in the step. The step is a step of loading the mask information from the HDD 3, and the mask information of the write address target address is
Load into buffer in The step is a step of loading data from the HDD3, and loads the data at the write target address into the buffer of the HDC2. The step is a step for obtaining data to be written, and includes mask information,
Data to be written to HDD3 is determined from original data on HDD3 and write data issued from CPU1. Step is HD
This is the step of writing data to D3.
Write the data from U1 to HDD3. Step 10 is a step of processing another command, and includes data reading, status reading, initialization processing, and the like.

FIG. 3 is a diagram showing a memory structure of a hard disk.

In the figure, reference numeral 31 denotes an area for holding a write protection target address. Reference numeral 32 denotes an area for storing mask information in sector units in the area 31. Reference numeral 33 denotes an area for storing data.

 Hereinafter, the operation of the embodiment of the present invention will be described.

The external storage device (HDD3, FDD5) is a controller (2/4)
Processed through That is, when a command issued from the CPU 1 is received, it is determined whether or not the command is a protection information setting command. If the command is a protection information setting command, the protection target address and the mask information in the address (sector) are read from the CPU 1 and the information is read. Is written to areas 31 and 32 on the external storage. If the command is not a protection information setting command, the process proceeds to step S to determine whether the command is a write command. If it is a write command, the step determines whether the write address is the address obtained in the step.
When the addresses match, the mask information is read from the area 32. Further, data written at the address is read from the area 33. Then, in a step, data to be written to the HDD 3 is generated from the mask information, the original data of the HDD 3 and the write data obtained from the CPU 1. The data created in the step is written to the area 33. If the result of the step is not a write protection target address,
Write the data itself from U1 to HDD3 (step).
Then, commands other than the write protection information setting command and the write command are processed.

[Effects of the Invention] As described above, according to the present invention, a write protection function for performing write protection on a sector basis using a write protection target address and write protection information for masking data on a sector basis is provided. Thus, it is possible to avoid the occurrence of an error in the write protection when accessing the external storage device under the management of the address on the main storage, which has conventionally been a problem.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a flowchart showing the operation of the embodiment of the present invention, and FIG. 3 is a diagram showing a memory structure of an external storage device. 1 ... CPU, 2 ... Hard disk controller (HD
C), 3 ... Hard disk drive (HDD), 8 ... RA
M.

Claims (1)

(57) [Claims] 1. An external storage device connected to a computer main body via a controller, comprising: a write protection information setting command output from the computer main body; a write protection target address and a sector unit output following the command. Means for inputting write protection information and writing the write protection target address and write protection information in a predetermined area in accordance with the write protection information setting command; means for receiving a write command output from the computer main body; Means for determining whether a write address of the command matches a write protection target address written in the predetermined area when a command is received, and a write address of the write command matches the write protection target address. When the write address The write protection information corresponding to the address is read, and based on the write protection information and the original data present at the write address and the write data received from the computer main body, update data is generated which is masked in accordance with the write protection information. Means for writing the update data to an area specified by the write address.