Electrical computers and digital processing systems: memory – Storage accessing and control – Specific memory composition
Reexamination Certificate
1998-09-28
2001-12-11
Thai, Tuan V. (Department: 2751)
Electrical computers and digital processing systems: memory
Storage accessing and control
Specific memory composition
C711S100000, C711S154000, C713S002000, C365S218000
Reexamination Certificate
active
06330634
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an external storage apparatus incorporating a storage means arranged to erase data in units of predetermined blocks and a data processing method for processing data which is stored in an external storage apparatus of the foregoing type.
2. Related Background Art
As external storage apparatuses of a type for use in a data processing apparatus, such as a personal computer or a digital still camera, external storage apparatuses of a type incorporating a so-called flash memory are known.
The external storage apparatus incorporating the flash memory has a structure that a storage region of the flash memory is divided into a plurality of blocks so as to manage a data region in block units. That is, erasing of data is performed in block units. If an unrecoverable error is made in the storage region, use of the block including the region in which the error has been made is inhibited. A block of the foregoing type is hereinafter called a use-inhibited block.
The external storage apparatus of the foregoing type has a structure that boot data containing information and so forth required to make an access to the external storage apparatus are previously stored in a predetermined block. When the external storage apparatus is booted up, boot data is initially read. Then, an access is made to the external storage apparatus in accordance with obtained boot data so that data is written/read.
In the external storage apparatus of the foregoing type, boot data usually contains information required to make an access to the external storage apparatus. If boot data cannot be read, the access to the external storage apparatus cannot be made. Therefore, boot data must have satisfactory reliability.
Hitherto, the block (hereinafter called a “boot block”) in which boot data is stored is a block formed at a predetermined position. Even if a boot block which is usually used is made to be the use-inhibited block, a copy of boot data is stored in another block so that boot data is read. In the conventional external storage apparatus, the reliability is furthermore improved by preparing a plurality of copies of boot data. Moreover, the copies are stored in different blocks. However, the method in which the multiplicity of the copies of boot data are prepared is an undesirable method in a viewpoint of effectively using the storage capacity.
Hitherto, when boot data has been updated, whether or not all of the copies of boot data have been updated to latest boot data has not been determined. Therefore, if the copy of boot data is not correctly updated to latest boot data in a certain operation, latest, that is, correct boot data cannot be read. In the foregoing case, there is apprehension that a correct access to the external storage apparatus cannot be made.
Hitherto, even if a copy of boot data is prepared, the copy is used only when reading of boot data of the original fails. Therefore, if the contents of original boot data are made to be incorrect because, for example, bits in a portion of the boot block in which original boot data has been stored are undesirably inverted, there arises a problem in that the foregoing boot data is as it is used if foregoing boot data can be read.
SUMMARY OF THE INVENTION
In view of the foregoing, an object of the present invention is to provide an external storage apparatus which is capable of effectively using a storage region thereof, with which an error cannot easily be made when boot data is read and which exhibits satisfactory reliability.
Another object of the present invention is to provide a data processing method with which the foregoing external storage apparatus can be realized.
According to one aspect of the present invention, there is provided an external storage apparatus which is arranged to erase data in units of predetermined blocks and which incorporates a block in which boot data which is first read when the external storage apparatus is booted up is stored. Boot data is stored in each of the blocks in which boot data has been stored. Moreover, an identification number indicating whether boot data stored in each block in which boot data has been stored is new or old is stored in each of the blocks.
The external storage apparatus according to the program is booted up such that latest boot data among boot data stored in the plurality of the different blocks is read in accordance with the identification number. Then, latest boot data is used so that the external storage apparatus is booted up.
The external storage apparatus according to the present invention is arranged such that whether boot data stored in the plurality of the different blocks is new or old is determined in accordance with the identification number when the external storage apparatus is booted up. If old boot data exists, old boot data is rewritten to latest boot data.
According to another aspect of the present invention, there is provided a data processing method with which boot data which is first read when an external storage apparatus arranged to erase data in units of predetermined blocks is booted up is stored in the external storage apparatus, the data processing method comprising the steps of: storing boot data in each of a plurality of different blocks; and storing an identification number which indicates whether boot data stored in the blocks is new or old in each of the blocks in which boot data has been stored.
The data processing method according to the present invention has a structure that when the external storage apparatus is booted up, latest boot data among boot data stored in the plurality of the different blocks is read in accordance with the identification number, and the external storage apparatus is booted up by using latest boot data.
The data processing method according to the present invention has a structure that when the external storage apparatus is booted up, whether boot data stored in the plurality of the different blocks is new or old is determined in accordance with the identification number, and old boot data is rewritten to latest boot data when old boot data exists.
Other objects, features and advantages of the invention will be evident from the following detailed description of the preferred embodiments described in conjunction with the attached drawings.
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Fuse Hiroaki
Sassa Akira
Frommer William S.
Frommer & Lawrence & Haug LLP
Savit Glenn F.
Sony Corporation
Thai Tuan V.
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