1、INTERNATIONAL STANDARD ISO/IEC 14251 First edition 1995-08-01 Information technology - Data interchange on 12,7 mm 36-track magnetic tape cartridges Technologies de /information - khange de don specify a different method of defining the ECC characters used to detect and correct errors when the data
2、is read from the tape. 2 Conformance 2.1 Magnetic tape cartridge A magnetic tape cartridge is in conformance with this International Standard if: the cartridge meets all the requirements of clauses 6 to 8 for either one of the two types of magnetic tape cartridge; the recording on the tape meets the
3、 requirements of clauses 9 to 13; for each recorded packet the algorithm used for processing the data therein, if Processed Data has been recorded, is defined and the identification is included in Byte 13 of the Packet ID of this packet (see 11.2). This identification shall conform to ISO/IEC 11576.
4、 2.2 Generating system A system generating a magnetic tape cartridge for interchange shall be entitled to claim conformance with this International Standard if all the recordings that it makes on a tape meet the mandatory requirements of this International Standard. A claim of conformance shall stat
5、e which types of magnetic tape cartridges it is capable of recording, whether or not one, or more, registered algorithms are implemented and, if so, the registered identifiers of all implemented algorithms. It shall also state whether it is capable of generating the optional VOLID Mark information.
6、2.3 Receiving system A system receiving a magnetic tape cartridge for interchange shall be entitled to claim conformance with this International Standard if it is able to handle any recording made on the tape according to this International Standard and specifies which of the two types of magnetic t
7、ape cartridges it is capable of reading. In particular it shall be able to retrieve data from individual packets within the extended blocks; be able to recognize that the data has been processed, to identify the algorithm(s) used, restore the data to its original form or to indicate to the host that
8、 it cannot do so; A claim of conformance shall state whether or not one, or more, registered algorithm(s) is (are) implemented and, if so, the registered identifier(s) of all implemented algorithms. It shall also state whether it is capable of using the optional VOLID Mark information. ISO/IEC 14251
9、 : 1995 (E) OISO/IEC 3 Normative references The following standards contain provisions which, through reference in this text, constitute provisions of this International Standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agr
10、eements based on this International Standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. Members of IEC and IS0 maintain registers of currently valid International Standards. ISO/IEC 646: 1991, IS0 683-13: 1986, IS0 1001: 1986,
11、 Information technology - IS0 7-bit coded character set for information interchange. Heat-treatable steels, alloy steels andfree-cutting steels - Part 13: Wrought stainless steels. Information processing - File structure and labelling of magnetic tapes for information interchange. IS0 1302: 1992, Te
12、chnical drawings - Method of indicating surface texture. ISO/IEC 11576: 1994, Information technology - Procedure for the registration of algorithms for the lossless compression of data. 4 Definitions For the purposes of this International Standard, the following definitions apply. 4.1 algorithm: A s
13、et of rules for transforming the logical representation of data. 4.2 algorithmically Processed Data: Data which has been processed by a defined processing algorithm. 4.3 Beginning of Tape (BOT): The point along the length of the magnetic tape, indicated by the start of recorded information. 4.4 byte
14、 An ordered set of eight bits (9 encoded bits) that are acted upon as a unit. 4.5 Cyclic Redundancy Check (CRC) character: A character represented by two bytes, placed at the end of a byte sting and used for error detection. 4.6 Data Records 4.6.1 Processed Data Record (PDR): The data entity result
15、ing from the application of an algorithm to the Logical Data Record. 4.6.2 Host Data Record: The data entity originally compiled by the host. 4.6.3 Logical Data Record (LDR): The data entity received by the system from the host. It may contain one or several Host Data Record(s) depending upon action
16、 taken by the host to use extended blocks. 4.6.4 User Data Record (UDR): The data entity available to the Packet Former. When the data has been processed it shall be a PDR. When the data has not been processed it shall be a LDR. 4.7 End of Tape (EOT): The point on the tape furthest from BOT up to wh
17、ich recording is allowed. 4.8 Error correcting code (ECC): A mathematical procedure yielding bits used for the detection and correction of errors. 4.9 flux transition position: The point on the magnetic tape that exhibits the maximum free-space flux density normal to the tape surface. 4.10 flux tran
18、sition spacing: The distance along a track between successive flux transitions. 4.11 Frame: A section across all 18 tracks within a Half-Wrap containing logically related bytes. 4.12 logical backwards: The direction of tape motion that results in finding a descending order of LDRs. 4.13 logical forw
19、ards: The direction of tape motion that results in finding an ascending order of LDRs. 4.14 magnetic tape: A tape that accepts and retains magnetic signals intended for input, output, and storage of data for information processing. 4.15 Master Standard Reference Tape: A tape selected as the International Standard for Reference Field, Signal Amplitude, Resolution, and Overwrite. NOTE 1 - A Master Standard Reference Tape has been established at the US National Institute of Standards and Technology (NIST). 2
