1、BRITISH STANDARD BS6542-1: 1984 ISO7665:1983 Incorporating Amendment No.1 Specification for File structure and labelling of flexible disk cartridges for information interchange Part1: Specification for sequential file allocation structure UDC 681.327.634.681.3.04BS6542-1:1984 This BritishStandard, h
2、aving been prepared under the directionof the Office and Information Standards Committee, was published underthe authority of the BoardofBSI and comes into effect on 31October1984 BSI04-2000 The following BSI references relate to the work on this standard: Committee referenceOIS/11 Draft for comment
3、82/63296DC ISBN 0 580 14110 1 Committees responsible for this British Standard The preparation of this BritishStandard was entrusted by the Office and Information Standards Committee (OIS/-) to Technical CommitteeOIS/11 upon which the following bodies were represented: British Computer Society Ltd.
4、British Telecommunications Business Equipment Trade Association Committee of London Clearing Bankers on behalf of London and Scottish Clearing Banks and Yorkshire Bank Local Authorities Organizations National Computing Centre Ltd. Amendments issued since publication Amd. No. Date of issue Comments 5
5、967 September 1988 Indicated by a sideline in the marginBS6542-1:1984 BSI 04-2000 i Contents Page Committees responsible Inside front cover National foreword ii 1 Scope and field of application 1 2 Conformance 1 3 References 1 4 Definitions 2 5 Notation 3 6 Arrangement of labels and files 3 7 File s
6、tructure for data interchange 5 8 Format and content of labels 7 9 Initialization and processing of label fields 13 10 Physical records 14 11 Levels of interchange 15 Annex A Examples 17 Annex B Data interchange standards and parameters 21 National appendix A Notes for the guidance of implementors 2
7、2 Table 1 Notation 3 Table 2 Parameters for data interchange standards 3 Table 3 Data interchange standards and parameter Recording-Type 3 Table 4 Sectors on the index cylinder (cylinder00) 4 Table 5 International Reference Version (see ISO646) showing characters permitted in labels 8 Table 6 Conten
8、ts of the Volume Label 9 Table 7 Contents of the File Label 10 Table 8 Contents of ERMAP Label 14 Table 9 Fields with assumed values in BASIC INTERCHANGE 16 Table 10 Parameter values 21 Publications referred to Inside back coverBS6542-1:1984 ii BSI 04-2000 National foreword This Part of BS6542 has b
9、een prepared under the direction of the Information Systems Technology Standards Committee. It is identical with ISO7665:1983 “Information processing File structure and labelling of flexible disk cartridges for information interchange”, published by the International Organization for Standardization
10、 (ISO), except that it includes National appendix A which is not part of the International Standard. National appendix A gives guidance for implementors. Although the scope and field of application of this part of BS6542 (see clause1) are similar to those of BS6542-2, this Part of BS6542 is applicab
11、le to200mm flexible disk cartridges which are not covered by BS6542-2. Terminology and conventions. The text of the International Standard has been approved as suitable for publication as a BritishStandard without deviation. Some terminology and certain conventions are not identical with those used
12、in BritishStandards; attention is drawn especially to the following. The comma has been used as a decimal marker. In BritishStandards it is current practice to use a full point on the baseline as the decimal marker. Wherever the words “International Standard” appear, referring to this standard, they
13、 should be read as Part of BS6542. A revision of BS4730 is in course of preparation to implement ISO646:1983 for use in the UK. The Technical Committee has reviewed the provisions of ISO2022, ISO5654-1 and ISO5654-2, ISO7065-1 and ISO7065-2 and ISO7487-1 and ISO7487-2, to which reference is made in
14、the text, and has decided that they are acceptable for use in conjunction with this standard. Further clarification of the status of ISO2022:1982 within the UK was given in a special announcement in BSI News, June1983; there is no corresponding BritishStandard at present. ECMA59 and ECMA78 are also
15、referenced in this standard, although they are not essential for determining compliance with the standard. Copies of ECMA standards may be obtained from ECMA,114 rue du Rhone, CH-1204 Geneva, Switzerland. Textual errors. When adopting the text of the International Standard, the textual errors given
16、below were discovered. They have been marked in the text and have been reported to the Secretariat of ISO/TC97/SC15 in a proposal to amend the text of the International Standard. Clause3, line15. In the title for ISO6596-1, “charcteristics” should be read as “characteristics”. Annex A, example6. The
17、re should be a broken line between the55 and457, as a downward extension of the solid line in the row above. This broken line should extend downwards to the solid horizontal line below the digits. Cross-references International Standard Corresponding British Standards ISO4873:1979 BS6006:1980 Specif
18、ication for United Kingdom8-bit data code (Identical)BS6542-1:1984 BSI 04-2000 iii 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 itsel
19、f confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pagesi toiv, pages1to22, 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 indicate
20、d in the amendment table on the inside front cover.iv blankBS6542-1:1984 BSI 04-2000 1 1 Scope and field of application This International Standard specifies requirements for the file structure and the labelling of flexible disk cartridges for the interchange of information between users of differen
21、t information processing systems. This International Standard specifies a) recorded labels to identify files, file sections, and volumes of flexible disk cartridges; b) basic characteristics of the blocks containing the records constituting the file; c) the file structure. This International Standar
22、d specifies three nested levels of interchange so that a) at the first level, called BASIC INTERCHANGE (BI), it is possible to interchange data by using a minimum set of the facilities provided; b) at the second level, called EXTENDED INTERCHANGE LEVEL1 (E1), it is possible to interchange data using
23、 the minimum set together with blocks having a length greater than that ofthe physical records and with blocked fixed-length records; c) at the third level, called EXTENDED INTERCHANGE LEVEL2 (E2), it is possible to interchange data using the facilities of levels BI and E1 together with variable-len
24、gth records and segmented records. Annex A describes examples but does not form part of this standard. Annex B gives disk parameter values derived from flexible disk data interchange standards, but does not form part of this standard. 2 Conformance A flexible disk cartridge conforms to this Internat
25、ional Standard when all interchange files and all labels recorded on it conform to the specifications of this International Standard. Astatement of conformity shall identify the level or levels of interchange to which the contents of the flexible disk cartridge conform. A prerequisite is conformance
26、 to the applicable flexible disk cartridge data interchange standards identified in this International Standard for the different types of flexible disks. 3 References ISO646, Information processing ISO7-bit coded character set for information interchange. ISO2022, Information processing ISO7-bit an
27、d8-bit coded character sets Code extension techniques. ISO4873, Information processing 8-bit coded character set for information interchange. ISO5654, Information processing Data interchange on200mm(8in) flexible disk cartridges using two-frequency recording at13262 ftprad on one side Part1: Dimensi
28、onal, physical and magnetic characteristics: Part2: Track format. ISO6596, Information processing Data interchange on130mm(5.25in) flexible disk cartridges using two-frequency recording at7958 ftprad on one side Part1: Dimensional, physical and magnetic charcteristics 1) : Part2: Track format for1,9
29、tpmm(48tpi) 2) ; ISO7065, Information processing Data interchange on200 mm(8in) flexible disk cartridges using modified frequency modulation recording at13262 ftprad on two sides Part1:Dimensional, physical and magnetic characteristics: Part2: Track format for1,9 tpmm(48tpi) 2) ; ISO7487, Informatio
30、n processing Data interchange on130 mm(5.25 in) flexible disk cartridges using modified frequency modulation recording at7958 ftprad on two sides Part1:Dimensional, physical and magnetic characteristics 2) : Part2: Track format 2) ; ECMA-59, Data interchange on200mm flexible disk cartridges using tw
31、o-frequency recording at13262 ftprad on both sides. ECMA-78, Data interchange on130mm flexible disk cartridges using MFM recording at7958 ftprad on both sides,3,8tracks per millimetre. 1) See national foreword for details of textual errors. 2) At present at the stage of draft.BS6542-1:1984 2 BSI 04-
32、2000 4 Definitions For the purpose of this International Standard, the following definitions apply. 4.1 block a group of characters treated as a logical unit 4.2 blocked an attribute of records and record segments that indicates that they may begin at a byte that is not the first byte of a block 4.3
33、 byte a string of eight binary digits operated upon as a unit 4.4 cylinder a pair of tracks, one on each side, having the same track number NOTE 1The cylinder number is a two-digit number identical to the track number. NOTE 2On flexible disk cartridges that are recorded only on one side, cylinders c
34、omprise one track only. 4.5 extent a set of physical records the addresses of which form a continuous ascending sequence 4.6 file a named collection of information consisting of records pertaining to a single subject 4.7 file section for a file recorded over more than one volume, that part of the fi
35、le that is recorded in any one volume 4.8 fixed-length record A record contained in a file in which all the records have the same length 4.9 formatting writing the proper control information establishing the cylinders and designating addresses of physical records on the surfaces of the flexible disk
36、 4.10 initialization writing of the Volume Label, the ERMAP Label, and any other information initially required to be on the flexible disk cartridge, prior to the commencement of general processing or use 4.11 label a record that identifies, characterizes and/or delimits a volume, a file or a file s
37、ection on that volume 4.12 natural order an ascending sequence of integers starting with the lowest allowed value and proceeding, in increments of one, to the highest allowed value 4.13 physical record a fixed-length field containing the data of a sector 4.14 physical record address a five-digit num
38、ber in which the cylinder address provides the two most significant digits, the side number provides the next most significant digit, and the sector number provides the two least significant digits 4.15 record related data treated as a unit of information 4.16 sector that part of a track on a flexib
39、le disk cartridge that can be accessed by the magnetic heads in the course of predetermined angular displacements of the disk 4.17 segmented record a record contained in a file in which each record consists of one or more consecutive record segments 4.18 track that part of a flexible disk that can b
40、e accessed by a single magnetic head that is stationary while the disk makes a complete revolution 4.19 variable-length record a record contained in a file in which the records may have different lengths 4.20 volume a dismountable physical unit of storage medium, for example a flexible disk cartridg
41、eBS6542-1:1984 BSI 04-2000 3 5 Notation 5.1 Specification of label content 5.1.1 In references to label contents throughout the following clauses of this International Standard, a notation is used with the significance shown in Table 1. Table 1 Notation 5.1.2 With the exception of SPACE, a group of
42、capital letters in the “content” column of a table specifying label contents indicates that the corresponding characters shall appear in the order given and in the corresponding character positions of the field specified for example, VOL in CP1 toCP3 of the Volume Label (see Table 6). In the tables
43、and throughout this International Standard, SPACE signifies the character coded in position2/0 of ISO646. 5.2 Label fields Where the words of this International Standard are used to signify a specific label or label field (for example “Sector Sequence Indicator”), the words are printed with initial
44、capitals throughout (except for prepositions). 6 Arrangement of labels and files 6.1 Applicability of this International Standard to identified types of flexible disk cartridge The requirements of this International Standard are applicable to several types of flexible disk cartridge. Each type of ca
45、rtridge is the subject of aseparate data interchange standard. These standards are identified in Table 3, together withthe corresponding values of a parameter Recording-Type. The parameter Recording-Type is used in this International Standard to identify the data interchange standard to which the ca
46、rtridge conforms, within the set of standards that apply to cartridges having the same physical dimensions. Table 2 identifies those numerical parameters that characterize the differences, between the types of cartridge, that are significant for the requirements of this International Standard. Table
47、 2 Parameters for data interchangestandards The values of the parameters listed in Table 2 shall be obtained from data interchange standards as specified below. The values applicable to the data interchange standards listed in Table 3 are quoted in Annex B. Number-Of-Sides: The number of sides of th
48、e disk on which recorded tracks shall be present. Cylinder-Limit: The specified minimum number of good cylinders that shall be present from cylinder01 to the cylinder having the highest specified cylinder number. Index-Sector-Limit: The number of usable sectors on Track00, Side0, or on Track00, Side
49、1. NOTEThese numbers shall be the same on both sides. Data-Sector-Limit: The number of usable sectors on each track other than Track00, on Side0 or Side1. Data-Physical-Record-Length: The number of bytes in the Data Field of a Data Block on each track other than Track00, on Side0 or Side1. Track-Data-Capacity: The numerical product oftheparameters Data-Sector-Limit and Data-Physical-Record-Length. Table 3 Data interchange standards and parameter Recording-Type 6.2 Number of sides Where this International Standard specifie
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