JPS60115085A - Magnetic tape file control method - Google Patents

Abstract

PURPOSE:To shorten the file control time for a magnetic tape by adding a header block at the head of each file to show the file information and therefore attaining the retrieval of the file from the present tape position without performing the rewind for each retrieval of file. CONSTITUTION:Files 3a, 3b,... divided by tape marks 2a, 2b,... consist of data blocks 6a, 6b,.... A header block 7 set at each head of files 3a, 3b,... includes an area 8 where the identification code of the block 7 is recorded and an area 9 where file numbers of files 3a, 3b,... are shown. When a specific file is retrieved, the file number is obtained from the area 9 of the block 7 and compared with the desired file number. Then a magnetic tape is rewound only in case the read- out file number is larger than the desired file number. When no coincidence is obtained from said comparison, the tape is advance for retrieval to read out the next file.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a magnetic tape file management method.

[Prior art]

Conventionally, this type of method has been shown in FIGS. 1 and 2. In FIG. 1, 1 is a hole indicating the starting end of the cassette magnetic tape, 2a to 2d are tape marks, and 3a to
3c is a file separated by tape marks 28-2d, 4 is an erasing area indicating the end of the sequence of files 3a-3C, and 5 is a hole indicating the end of the tape. FIG. 2 is a format diagram of each of the files 3a to 3C. Each file 3
a to 3C are composed of a plurality of data blocks 6a to 6d.

Next, the operation will be explained. An example will be explained in which a computer searches for, for example, file 3b having a desired file number. First, the tape is rewound and moved from hole 1 to the starting end side. Next, a search is performed for the first tape mark 2a. The number of detected tape marks 2a is compared with the desired file number. In this case, since the number of arp marks is smaller than the file number of file 3b, the tape is further advanced in the end direction and a search for tape mark 2b is performed. Since the number of tape marks and the file number match, tape mark 2b
The file 3b following is the desired one. If the number of tape marks and the file number do not match even after searching up to erase area 4, it is interpreted that the desired file does not exist.

Conventional cassette file management methods have the trap structure described above, so in order to search for the desired file, even if the current tape position is on the desired file, the tape must be rewound to the beginning. However, it also had the disadvantage of being inefficient in terms of time.

[Summary of the invention]

This invention was made to eliminate the drawbacks of the conventional methods as described above. By adding a header block indicating information about the file to the beginning of each file, it is possible to search for a file from the current tape position. The purpose of this paper is to provide a magnetic tape file management method that can be used to manage files on magnetic tape.

[Embodiments of the invention] An embodiment of the present invention will be described below with reference to the drawings.

FIG. 3 is a format diagram of each of the files 3a to 3c in FIG. 1. In the figure, 6a to 6C are data blocks, 7 is a header block placed at the beginning of each file 3a to 3c and stores the respective header information, 8 is an area for recording the identification code of header block 7, and 9 is a file This is an area showing file numbers 3a to 3C.

Next, the operation of the above configuration will be explained with reference to the drawings, taking as an example the case of searching for a desired file.

First, in step 10, tape marks 2a to 2d are searched, and then a file number is written from area 9 of header block 7. In step 11, the desired file number and the detected file number are compared. Both files If the numbers match (-), the file search is completed. If the desired file number is smaller than the detected file number (<), proceed to step 12;
Perform tape rewind. Conversely, if it is larger (>), the process proceeds to step 13, where the tape is advanced and the same process as step 10 is performed. In step 14, it is checked whether the subsequently read block is in the erase area 4,
If it is erase area 4, it means that the desired file does not exist, and the process ends with an error. If it is not erase area 4 but files 3a to 3C, the detected file number and the desired file number are compared in step 15, and if they match, the file search is completed, and if the detected file number is larger (<) indicates an error termination. In other cases (-, >), the processes from step 13 to step 15 are repeated until the file search is completed or the desired file does not exist and the process ends with an error.

Further, in the above embodiment, the header block 7 is provided with an area 9 indicating the file number, but the header block T may also be provided with an area indicating the number of data blocks included in the file. It has a similar effect.

〔Effect of the invention〕

As described above, according to the present invention, a header block indicating information about the file is added to the beginning of the file.
There is no need to rewind each time a file is searched, which has the effect of shortening the time required to search for a file.

[Brief explanation of the drawing]

FIG. 1 is a recording format diagram of a cassette magnetic tape, FIG. 2 is a conventional file format diagram, FIG. 3 is a file format diagram according to an embodiment of the present invention, and FIG.
The figure is a flow diagram of the process of searching for files according to the present invention. 1.5... Hole, 2... Tape mark, 3... File, 4... Erase area, 6... Data block, 7
...Header block, 8.9...Area. In addition, in the figures, the same symbols indicate the same or corresponding parts.

Claims (1)

[Claims] An area is provided in the first block of each file recorded on the magnetic tape to record the number of the file, and when searching for a specific file, the number of the file read from the magnetic tape and the number of the specific file are combined. Compare the
The magnetic tape is rewound only when the number of the read file is greater than the number of the specific file, and when they do not match, the magnetic tape is advanced to read the next file. magnetic tape file management method.