1、BRITISH STANDARD BS 6542-2: 1988 EN 29293:1989 ISO 9293:1987 Incorporating Amendment No. 1 File structure and labelling of flexible disk cartridges for information interchange Part 2: Specification for variable file allocation structure ISO title: Information processing Volume and file structure of
2、flexible disk cartridges for information interchange The European Standard EN 29293:1989has the status of a British Standard UDC 681.327.634:681.3.04BS6542-2:1988 This British Standard, having been prepared under the directionof the Information Systems Technology Standards Committee, was published u
3、nderthe authority of the BoardofBSI and comes into effect on 30September1988 BSI 01-2000 The following BSI references relate to the work on this standard: Committee reference IST/11 Draft for comment 87/97533 DC ISBN 0 580 16705 4 Committees responsible for this British Standard The preparation of t
4、his British Standard was entrusted by the Information Systems Technology Standards Committee (IST/-) to Technical Committee IST/11, upon which the following bodies were represented: Association for Payment Clearing Services British Computer Society Business Equipment and Information Technology Assoc
5、iation Institute of Data Processing Management Local Authority Organizations National Centre for Information Media and Technology (CIMTECH) National Computing Centre Ltd. Amendments issued since publication Amd. No. Date of issue Comments 7046 February 1992 Indicated by a sideline in the marginBS654
6、2-2:1988 BSI 01-2000 i Contents Page Committees responsible Inside front cover National foreword ii Brief history 2 Section 1. General 0 Introduction 3 1 Scope and field of application 3 2 Conformance 3 3 References 4 4 Definitions 4 5 Notations 5 Section 2. Requirements for the medium 6 Volume stru
7、cture 5 7 Contents of a file 8 8 Recording of descriptor fields 9 9 FDC Descriptor 9 10 File Allocation Table 10 11 File directories 11 Section 3. Requirements for systems 12 Requirements for the description of systems 15 13 Requirements for an originating system 15 14 Requirements for a receiving s
8、ystem 16 Section 4 15 Record structure 16 Annex A Parameter values for FDCs conforming to an International Standard for data interchange 18 Annex B Parameter values for other FDC formats 19 Annex C ISO 646: International Reference Version (IRV) 20 Annex D Example of volume structures and file locati
9、on 22 Annex E Index of acronyms 25 Table 1 5 Table 2 6 Table 3 9 Table 4 11 Table 5 20 Table 6 21 Table 7 23 Table 8 24 Table 9 24 Publications referred to Inside back coverBS6542-2:1988 ii BSI 01-2000 National foreword This Part of BS6542has been prepared under the direction of the Information Syst
10、ems Technology Standards Committee. It is identical with ISO9293:1987 “Information processing Volume and file structure of flexible disk cartridge for information interchange” published by the International Organization for Standardization (ISO). Although the scope and field of application of this P
11、art of BS6542 (see clause 1) are similar to those of BS6542-1, the use of this Part of BS6542has a number of practical advantages over BS6542-1which are summarized in clause 0. However, this Part of BS6542is not applicable to200mm flexible disk cartridges, for which BS6542-1should still be used. In1
12、989the European Committee for Standardization (CEN) accepted ISO9293 as European Standard EN29293:1989. Terminology and conventions. The text of the International Standard has been approved as suitable for publication as a British Standard without deviation. Some terminology and certain conventions
13、are not identical with those used in British Standards; attention is drawn especially to the following. For metric units the comma has been used as a decimal marker. In British Standards it is current practice to use a full point on the baseline as the decimal marker. Wherever the words “Internation
14、al Standard” appear, referring to this standard, they should be read as “Part of BS6542”. Cross-references International Standard Corresponding British Standard ISO646:1983 BS4730:1985 Specification for UK7-bit coded character set (Identical, exercising national options) BS7024 Guide to construction
15、 and use of130mm (5.25in) flexible disk cartridges for data interchange, using modified frequency modulation recording at7958ftprad, 1.9tpmm (48tpi) on both sides ISO7487-1:1985 Part 1:1988 Dimensional, physical and magnetic characteristics (Identical) ISO 7487-3:1986 Part 3:1988 Track format B (Ide
16、ntical) ISO 7665:1983 BS 6542 File structure and labelling of flexible disk cartridges for information interchange Part 1:1984 Specification for sequential file allocation structure (Identical) BS 7023 Guide to the construction and use of130mm (5.25in) flexible disk cartridges for data interchange,
17、using modified frequency modulation recording at7958ftprad, 3.8tpmm (96tpi) on both sides ISO 8378-1:1986 Part 1:1986 Dimensional, physical and magnetic characteristics (Identical) ISO 8378-3:1986 Part 3:1986 Track format B (Identical) BS 6957 Guide to construction and use of130mm (5.25in) flexible
18、disk cartridges for data interchange, using modified frequency modulation recording at13262ftprad, on80tracks on each sideBS6542-2:1988 BSI 01-2000 iii NOTEIn clause 0, paragraph2, the first item should read “The interchange file will be especially suitable for direct updating by interactive applica
19、tion”. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. International Standard Correspondi
20、ng British Standard ISO 8630-1:1987 Part 1:1988 Dimensional, physical and magnetic characteristics (Identical) ISO 8630-3:1987 Part 3:1988 Track format B for80tracks (Identical) BS 6958 Guide to construction and use of90mm (3.5in) flexible disk cartridges for data interchange, using modified frequen
21、cy modulation recording at7958ftprad, 5.3tpmm (135tpi) on80tracks on each side ISO 8860-1:1987 Part 1:1988 Dimensional, physical and magnetic characteristics (Identical) ISO 8860-2:1987 Part 2:1988 Track format (Identical) Summary of pages This document comprises a front cover, an inside front cover
22、, pages i to iv, theENtitle page, pages 2to 26, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.iv blankEUROPEAN STANDARD NORME EUROPNNE EUROPI
23、SCHE NORM EN29293 March1989 UDC 681.327.63.04 Descriptors: Data processing, information interchange, flexible disk cartridges, magnetic recording, files, organization of data, volume English version Information processing Volume and file structure of flexible disk cartridges for information intercha
24、nge (ISO 9293, 1st edition, 1987) Traitement de linformation Volume et structure des fichiers des cartouches disquette pour lchange dinformation (ISO9293, lre dition, 1987) Informationsverarbeitung Kennstze und Dateianordnung auf Diskette fr den Datenaustausch (ISO9293, 1Ausgabe, 1987) This European
25、 Standard was approved by CEN on1988-12-21. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning
26、such national standards may be obtained on application to the Central Secretariat or to any CEN member. This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CEN member into its own langua
27、ge and notified to the Central Secretariat has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and Un
28、itedKingdom. CEN European Committee for Standardization Comit Europen de Normalisation Europisches Komitee fr Normung Central Secretariat: rue de Stassart 36, B-1050 Brussels CEN1989Copyright reserved to all CEN members Ref. No. EN29293:1989EEN 29293:1989 BSI 01-2000 2 Brief history The Technical Bo
29、ard has decided to submit the International Standard ISO9293, 1st edition1987 “Information processing; Volume and file structure of flexible disk cartridges for information interchange” to the formal vote. The result of this vote was positive. For the time being, this document exists only in the Eng
30、lish and the French versions. According to the CEN/CENELEC Common Rules, the following countries are bound to implement this standard: Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and Unite
31、dKingdom. Statement The text of the International Standard ISO9293, 1st edition, 1987, was approved by CENas a European Standard without any modification.EN 29293:1989 BSI 01-2000 3 Section 1. General 0 Introduction For many purposes ISO7665provides a satisfactory data interchange between different
32、types of information-processing systems. However, it imposes some restrictions on the operation of a system as follows: a) Each individual file must be recorded on the disk in a sequential, “batch-processing” mode. After a set of files has been recorded on the disk, a file cannot be extended beyond
33、its pre-determined length. It is common practice in small systems for the user to interact continuously with the system to update files. Files having a suitable structure for this purpose are not within the provision of ISO7665. The interchange cartridge has to be created by an “export” copy process
34、 from the applications files, after the application has terminated. A similar “import” process is required in the receiving system. b) Limitations on the number of file labels permitted on an interchange FDC prevents the full use of the disk space if the average size of files is significantly less t
35、han, say20kbytes. For conventional data processing purposes this is usually satisfactory. However, the file sizes typically encountered in text processing and small single-user systems are very much smaller and would lead to very inefficient use of the disk space. In view of these requirements it wa
36、s decided to develop a second standard for volume and file structure of flexible disk cartridges, the provisions of which were to be based on already existing practice in general use world-wide. Hence this International Standard has the following beneficial characteristics, in addition to those of I
37、SO7665. The interchange file will be especially for direct updating by interactive application. There will be no limit on the number of individual files on an FDC, within the overall limitation of available space for holding files. Any file can be extended whenever required. These characteristics ar
38、e advantageous for: interchange of sets of text files or of small files, or of multiple-part document files; interchange of any file when sender and recipient wish to carry out frequent update of the file between interchange cycles, for example files of commercial transactions. 1 Scope and field of
39、application This International Standard specifies the volume and file structure of flexible disk cartridges (FDC) for the interchange of information between users of information processing systems. It also specifies an optional record structure. This International Standard is applicable to various t
40、ypes of flexible disk cartridges including those identified in clause 3, and other types which may be the subject of future International Standards. This International Standard specifies the location of files of information on a flexible disk cartridge, and also specifies a set of recorded descripto
41、rs which identifies: the files which may be interchanged; the locations of the files; the attributes of the files; the location of unused space for recording on the FDC; the location of defective recording space on the FDC; the attributes of the FDC and of the descriptors recorded on it. This Intern
42、ational Standard also specifies requirements for the processes which are provided within information processing systems to enable information to be interchanged between different systems, utilizing recorded flexible disk cartridges as the medium of interchange. For this purpose it specifies the func
43、tions within systems which are intended to originate or to receive flexible disk cartridges which conform to this International Standard. This International Standard provides a method for the allocation of space that is independent of the number of files that are recorded on the volume. It also enab
44、les the sizes of the recorded files to be expanded or contracted during processing, subject only to the availability of unused recording space when needed. The contents and organization of the files are not specified by this International Standard and are subject to agreement between the originator
45、and the recipient of the interchanged FDC. 2 Conformance 2.1 Conformance of a flexible disk cartridge A flexible disk cartridge shall be in conformance with this International Standard when all information recorded on it conforms to the requirements of section 2of this International Standard.EN 2929
46、3:1989 4 BSI 01-2000 A prerequisite to such conformance is the conformance of the flexible disk cartridge to the appropriate International Standard for data interchange of flexible disk cartridges. 2.2 Conformance of an information processing system An information processing system shall be in confo
47、rmance with this International Standard if it meets the set of requirements specified in section3of this International Standard either for an originating system, or for a receiving system, or for both types of system. A statement of conformance shall identify which of these sets of requirements is m
48、et by the system. Conformance with this International Standard does not require conformance with section 4. 3 References ISO646, Information processing ISO7-bit coded character set for information interchange. ISO7487, Information processing Data interchange on130mm (5.25in) flexible disk cartridges
49、 using modified frequency modulation recording at7958ftprad, 1,9tpmm (48tpi), on both sides. Part 1: Dimensional, physical and magnetic characteristics. Part 3: Track format B. ISO7665, Information processing File structure and labelling of flexible disk cartridges for information interchange. ISO8378, Information processing Data interchange on130mm (5.25in) flexible disk cartridges using modified frequency modulation recording at7958ftprad, 3,8tpmm (96tpi), on both sides. Part 1: Dimensional, physical and magnetic
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