Electrical computers and digital processing systems: memory – Storage accessing and control – Memory configuring
Reexamination Certificate
1999-02-09
2001-08-07
Verbrugge, Kevin (Department: 2185)
Electrical computers and digital processing systems: memory
Storage accessing and control
Memory configuring
C711S112000
Reexamination Certificate
active
06272611
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a computer data storage medium and a memory management method therefor, more particularly to a memory management method in which a computer data storage medium is configured to include at least one virtual disk drive.
2. Description of the Related Art
At present, partitioning schemes are available in the art to permit partitioning of a computer data storage medium, such as a hard disk, a floppy disk or a portable data storage device, into several system disk drives for storing system files therein, and a data disk drive to be commonly shared by the system disk drives, thereby resulting in efficient use of memory space. Moreover, back-up schemes are available in the art so that, when a system file is modified, the initial version of the system file is stored as a back-up file, while the modified version of the system file is stored as the new system file. Thus, when the new system file is corrupted, such as by a computer virus, portions of the new system file can still be recovered due to the presence of the back-up file.
A main drawback of the known back-up scheme resides in that a system file cannot be restored to its initial installed form once the system file has undergone numerous modifications.
A mirror scheme is also available in the art, wherein the contents of a master hard disk are copied into a slave hard disk so that, when the master hard disk is damaged, the contents of the master hard disk are still available due to the presence of the slave hard disk. However, the known mirror scheme does not provide protection against computer viruses since a computer virus written into the master hard disk is also copied into the slave hard disk.
In co-pending U.S. Pat. No. 6,016,536, entitled “Memory Management Method for a Computer With a Hard Disk Drive,” and filed by the applicant on Nov. 13, 1997, there is disclosed a memory management method for a computer with a hard disk drive which can provide adequate protection to the hard disk drive against computer viruses and which permits restoration of system files in the hard disk drive to their initial form. In the disclosed memory management method, the hard disk drive is partitioned into at least one system disk drive for storing system files therein, a data disk drive, a system buffer space, and a read/write table. Then, the computer is operated in one of an unrestricted mode, where storing of the system files and modifying of the system files in the system disk drive by the computer are permitted, and a restricted mode, where modified portions of the system files in the system disk drive are stored by the computer in the system buffer space instead of the system disk drive to maintain the system files in the system disk drive in their initial form and where the read/write table is updated by the computer to record addresses of the modified portions in the system buffer space and addresses of portions of the system files in the system disk drive corresponding to the modified portions therein. The computer is enabled to read (or write into) the data disk drive when the read (or write) address is in the data disk drive regardless of whether the computer is operated in the restricted or unrestricted mode.
In the aforesaid memory management method, the flexibility of the computer data storage medium is affected because of the need to partition the same to form a data disk drive. Inefficient use of memory space occurs if a relatively large storage space is allocated for the data disk drive. If the size allocated for the data disk drive is relatively small to minimize waste of storage space, the data disk drive will be easily filled up during use, thereby arising in the need to repartition the computer data storage medium anew.
SUMMARY OF THE INVENTION
Therefore, the object of the present invention is to provide a computer data storage medium that dispenses with the need to partition the same into system and data disk drives while providing adequate protection against computer viruses and permitting restoration of system files in the computer data S storage medium to their initial form.
More specifically, the object of the present invention is to provide a computer data storage medium that is configured to include a system disk drive and at least one virtual disk drive that appears as a file name in a file description area of the system disk drive and that shares free storage space of the computer data storage medium with the system disk drive to result in greater flexibility when the computer data storage medium is in use.
Another object of the present invention is to provide a memory management method for configuring, reading and writing into a computer data storage medium.
According to one aspect of the invention, a computer data storage medium comprises a system disk drive that is configured to include a starting data region having a system drive description area and a starting data area for storing system files, and at least one virtual disk drive that appears as a file name in the system drive description area of the starting data region and that is not allocated with a predetermined amount of memory space.
Preferably, the system disk drive is further configured to include a system buffer file for storing user-modified portions of the system files residing in the starting data area, and a read/write record file for recording addresses of portions of the system files in the starting data area and corresponding to the user-modified portions stored in the system buffer file. The system buffer file appears as a file name in the system drive description area of the starting data region and is not allocated with a predetermined amount of memory space.
Preferably, the virtual disk drive is configured to include a virtual drive description region, a protected data area for storing system files, a virtual drive buffer file for storing user-modified portions of the system files residing in the protected data area, and a read/write record file for recording addresses of portions of the system files in the protected data area and corresponding to the user-modified portions stored in the virtual drive buffer file. The virtual drive buffer file appears as a file name in the virtual drive description region and is not allocated with a predetermined amount of memory space.
According to another aspect of the invention, a memory management method for a computer data storage medium comprises configuring the computer data storage medium to include a system disk drive that has a starting data region with a system drive description area and a starting data area for storing system files, and at least one virtual disk drive that appears as a file name in the system drive description area of the starting data region and that is not allocated with a predetermined amount of memory space.
Preferably, the system disk drive further has a system buffer file for storing user-modified portions of the system files residing in the starting data area, and a read/write record file for recording addresses of portions of the system files in the starting data area and corresponding to the user-modified portions stored in the system buffer file. The system buffer file appears as a file name in the system drive description area of the starting data region and is not allocated with a predetermined amount of memory space.
The memory management method further comprises selectively operating a computer in an unprotected mode, where storing of the system files in the starting data area and modifying of the system files in the starting data area by the computer are permitted, and a protected mode, where the user-modified portions of the system files in the starting data area are stored by the computer in the system buffer file instead of the starting data area to maintain the system files in the system disk drive in their initial form, and where the read/write record file is updated by the computer to record the addresses of the portions of the system files in the starting data area that corr
Townsend and Townsend / and Crew LLP
Verbrugge Kevin
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