A virtual optical disk method to realize rewritability and revision control on a write‐once optical disk

Abstract This paper proposes a virtual optical disk method which uses the write‐once optical disk as a rewritable secondary memory on existing operating systems. The method also provides revision history of all files on an optical disk. The virtual disk method realizes a virtually rewritable disk (virtual disk), using the write‐once optical disk. The rewriting is simulated using the disk sector as the unit. It completes re‐writability and revision control without additional rewritable memory devices such as magnetic disks. The method is actually built into an OS for a personal computer, and the access speed of a virtual disk is made almost equal to that of a floppy disk by adding an optical disk cache memory. The virtual disk method has a merit in that it can cope with write‐errors in a write‐once optical disk, which may occur consecutively at writing process. Thus, it is seen that the virtual optical disk method is a useful means of this medium management.