SIST EN 29293:1997

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Information processing - Volume and file structure of flexible disk cartridges for information interchange (ISO 9293:1987)Informationsverarbeitung - Kennsätze und Dateianordnung auf Diskette für den Datenaustausch (ISO 9293:1987, Ausg. 1)Traitement de l'information - Volume et structure des fichiers des cartouches a disquette pour l'échange d'information (ISO 9293:1987, éd. 1)Information processing - Volume and file structure of flexible disk cartridges for information interchange (ISO 9293:1987, ed. 1)35.220.21Magnetni diskiMagnetic disksICS:Ta slovenski standard je istoveten z:EN 29293:1989SIST EN 29293:1997en01-december-1997SIST EN 29293:1997SLOVENSKI
STANDARD



SIST EN 29293:1997



SIST EN 29293:1997



SIST EN 29293:1997



INTERNATIONAL STANDARD INTERNATIONAL ORGANIZATION FOR STANDARDIZATION ORGANISATION INTERNATIONALE DE NORMALISATION MEXAYHAPOAHAR OPTAHM3ALWlR no CTAHAAPTM3AL(MM Information processing - Volume and file structure of flexible disk cartridges for information interchange Traitement de i'information - Volume et structure des fichiers des cartouches à disquette pour i'échange d'information :so ,293 'irst edition 987-04-15 Reference number 170 9293 : 1987 (E) &! SIST EN 29293:1997



Foreword IS0 (the International Organization for Standardization) is a worldwide federation of national standards bodies (IS0 member bodies). The work of preparing International Standards is normally carried out through IS0 technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, govern- mental and non-governmental, in liaison with ISO, also take part in the work. Draft International Standards adopted by the technical committees are circulated to the member bodies for approval before their acceptance as International Standards by the IS0 Council. They are approved in accordance with IS0 procedures requiring at least 75 % approval by the member bodies voting. International Standard IS0 9293 was prepared by the European Computer Manufac- turers Association (as Standard ECMA-107) and was adopted, under a special "fast- track" procedure, by Technical Committee ISO/TC 97, Information processing systems, in parallel with its approval by the IS0 member bodies. ' Users should note that all International Standards undergo revision from time to time and that any reference made herein to any other International Standard implies its latest edition, unless otherwise stated. O International Organization for Standardization, 1991 0 Printed in Switzerland SIST EN 29293:1997



Contents Section one : General IS0 9293 : 1987 (E) Page . O Introduction 1 Scope and field of application . 2 Conformance . 2.1 2.2 Conformance of a flexible disk cartridge . Conformance of an information processing system . . 3 References . 4 Definitions 4.1 byte . 4.2 4.3 data interchange standard . 4.4 defective sector 4.5 descriptor . 4.6 file . 4.7 formatting . 4.8 implementation . 4.9 initialization . 4.10 originating system . 4.11 receiving system . data field of a sector . . 4.12 sector . 4.13 track 4.14 user . 4.15 fixed-length record . 4.16 record . 4.17 segment . 4.18 segmented record . 4.19 variable-length record . . . 5 Notations 5.1 Decimal and hexadecimal notations . 5.2 Other notations . 5.3 Capital letters . Section two : Requirements for the medium . 6 Volume structure 6.1 Arrangement of data on a flexible disk cartridge . 6.1.1 FDC parameters . 6.1.2 Physical Addresses . 6.1.3 Logical Sector Number . 6.1.4 System Area and Data Area . 6.1.5 Parameters of the Volume Structure . Arrangement of the Data Area . 6.2.1 Clusters . 6.2.2 Status of clusters . Arrangement of the System Area . 6.3.1 FDC Descriptor and space for system use . 6.3.2 File Allocation Table (FAT) . 6.3.3 Root Directory . 6.3.4 Size of the System Area . 6.4 Files . 6.4.1 File Space . 6.4.2 Relation to clusters . 6.4.3 File length . 6.2 6.3 . 6.5 Sub-directories . 7 Contents of a file 1 1 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 4 4 4 4 4 5 5 5 5 5 5 5 5 5 6 6 iii SIST EN 29293:1997



IS0 9293 : 1987 (E) Page 8 Recording of descriptor fields . 6 8.1 Numerical values in one-byte fields . 6 8.2 Numerical values in two-byte fields . 6 8.3 Numerical values in four-byte fields . 6 8.4 Pairs of 12-bit integers . 6 8.5 Character set and coding . 6 8.6 Justification of characters . 7 9 FDCDescriptor . 7 9.1 FDC Descriptor layout . 7 9.2 FDC Descriptor fields . 7 9.2.1 7 9.2.2 Creating System Identifier (BP 4 to 11) . 7 9.2.3 Sector Size (BP 12and 13) . 7 9.2.4 Sectors per Cluster (BP 14) . 7 9.2.5 Reserved Sector Count (BP 15and 16) . 7 9.2.6 Number of FATS (BP 17) . 7 9.2.7 Root Directory Entries (BP 18 and 19) . 7 9.2.8 Total Sectors (BP20and21) . 7 9.2.9 Medium Identifier (BP22) . 7 9.2.10 Sectors per FAT (BP23 and 24) . 7 9.2.11 Sectors per Track (BP 25 and 26) . 8 9.2.12 Number of Sides (BP 27 and 28) . 8 9.2.13 Field reserved for future standardization (BP 29 and 30) . 8 9.2.14 Field reserved for system use (BP 31 to 512) . 8 10 File Allocation Table . 8 10.1 Format Identifier . 8 10.2 FATenties . 8 10.2.1 FATentrysize . 8 10.2.2 Number of FAT entries . 8 10.2.3 FAT entry values . 8 10.2.4 Maximum Cluster Number (MAX) . 8 10.3 Number of sectors in each FAT . 8 10.4 Recorded form of the FAT . 9 11 File directories . 9 11.1 Characteristics . 9 11.2 Directoryentry types . 9 11.3 General definition of Directory Entry Fields . 9 11.3.1 Name(BP1 to81 . 9 11.3.2 NameExtension(BP9to11) . 9 11.3.3 Attributes (BP 12) . 9 11.3.4 Reserved Field (BP 13to22) . 10 11.3.5 Time Recorded (BP23and 24) . 10 Field reserved for system use (BP 1 to 3) . 11.3.6 Date Recorded (BP25and26) . 11.3.7 Starting Cluster Number (BP27and28) . 11.3.8 File Length (BP 29 to 32) . File Entry . 11.4.1 Name (BP 1 to8) . 11.4.2 Name Extension (BP9 to 11) . 11.4.3 Attributes (BP 12) . 11.4.4 Reserved Field (BP 13 to22) . 11.4.5 Time Recorded (BP23and24) . 11.4.6 Date Recorded (BP 25 and 26) . 11.4.7 Starting Cluster Number (BP 27and 28) . 11.4.8 File Length (BP29to32) . Volume Label Entry . 11.5.1 Nameand Name Extension (BP 1 to 11) . 11.5.2 Attributes (BP 12) . 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 SIST EN 29293:1997



..I * IS0 9293 : 1987 (E) Page 11.5.3 Reserved Field (BP 13 to22) ............................. 11.5.4 Tirne Recorded (BP23and24) ........................... 11.5.5 Date Recorded (BP25and 26) ............................ 11.5.6 Starting Cluster Number (BP 27 and 28) ................... 11.5.7 File Length (BP 29 to 32) ................................ 11.6 Sub-directory Pointer Entry ..................................... 11.6.1 Name(BP1 to8) ....................................... 11.6.2 NameExtension(BP9toll) ............................. 11.6.3 Attributes (BP 12) ...................................... 11.6.4 Reservedfield (BP 13to22) .............................. 11.6.5 Time Recorded (BP 23 and 24) ........................... 11.6.6 Date Recorded (BP25and26) ............................ 11.6.7 Starting Cluster Number (BP 27 and 28) ................... 11.6.8 File Length (BP29to32) ................................ 11.7 Sub-directory Identifier Entry .................................... 11.7.1 Name(BP1 to8) ....................................... 11.7.2 Name Extension (BP9 to 11) ............................. 11.7.3 Attributes (BP 12) ...................................... 11.7.4 Reserved Field (BP 13 to 22) ............................. 11.7.5 TimeRecorded(BP23and24) ........................... 11.7.6 Date Recorded (BP25and 26) ............................ 11.7.7 Starting Cluster Number (BP 27 and 28) ................... 11.7.8 File Length (BP29to32) ................................ Sub-directory Parent Pointer entry ............................... 11.8.1 Name(BP1 to81 ....................................... 11.8.2 NameExtension(BP9toll) ............................. 11.8.3 Attributes (BP 12) ...................................... 11.8.4 Reserved Field (BP 13 to221 ............................. 11.8.5 Time Recorded (BP 23 and 24) ........................... 11.8.6 Date Recorded (BP25and 26) ............................ 11.8.7 Starting Cluster Number (BP27and 28) ................... 11.8.8 FileLength(BP29to32) ................................ 11.9 Not-currently-used Entry ....................................... 11.9.1 Name Field (BP 1 to 18) ................................. 11.9.2 Remaining bytes (BP9 to32) ............................ 11.10 Never-used Entry ............................................. 11.10.1 NameField(BP1 to81 ................................. 11.10.2 Remaining bytes (BP 9 to 32) ........................... 11.8 10 11 11 11 11 11 11 11 11 11 11 11 11 11 11 11 11 11 11 11 11 11 12 12 12 12 12 12 12 12 12 12 12 12 12 12 12 12 Section three: Requirements for systems 12 Requirements for the description of systems ............................ 13 13 Requirementsfor an originating system ................................. 13 13.3 Descriptors ................................................... 13 ...................................................... ......................................................... 13.1 General 13 13.2 Files 13 14 Requirements for a receiving system ................................... 13 14.3 Descriptors ................................................... 13 ...................................................... ......................................................... 14.1 General 13 14.2 Files 13 Section four: Record structure .................................................... 15 Record structure 14 15.1 General ...................................................... 14 15.2 Records 14 ...................................................... 15.2.1 Characteristics ......................................... 14 15.2.2 Measured Data Units ................................... 14 15.2.3 Fixed-length records .................................... 14 V SIST EN 29293:1997



IS0 9293 : 1987 (E) Page 15.2.4 Variable-length records . 14 15.2.5 Segmented records . 14 15.3 Attributes of record-structured files . 15 15.4 Requirements for systems implementing section four . 15 15.4.1 Originating systems . 15 15.4.2 Receiving systems . 15 Annexes A . Parameter values for FDCs conforming to an International Standard for data interchange . 16 B . Parameter values for other EDC formats . 17 C . IS0 646: International Reference Version (IRV) . 18 D . Example of volume structures and file location . 20 E . Index of acronyms . 23 vi SIST EN 29293:1997



__ ~~ INTERNATIONAL STANDARD IS0 9293 : 1987 (E) Information processing - Volume and file structure of flexible disk cartridges for information interchange Section one : General O Introduction For many purposes IS0 7665 provides a satisfactory data inter- change between different types of information-processing systems. However, it imposes some restrictions on the opera- tion of a system as follows : a) Each individual file must be recorded on the disk in a se- quential, "batch-processing" mode. After a set of files has been recorded on the disk, a file cannot be extended beyond its pre-determined length. It is common practice in small systems for the user to inter- act continuously with the system to update files. Files having a suitable structure for this purpose are not within the provision of IS0 7665. The interchange cartridge has to be created by an "export" copy process from the application's files, after the applica- tion 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 than, say 20 kbytes. For conventional data processing purposes this is usually satisfactory. However, the file sizes typically en- countered 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 was 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 Inter- national Standard has the following beneficial characteristics, in addition to those of IS0 7665. - 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 are 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 application This International Standard specifies the volume and file struc- ture 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 types of flexible disk cartridges including those identified in clause 3, and other types which may be the subject of future Inter- national Standards. This International Standard specifies the location of files of in- formation on a flexible disk cartridge, and also specifies a set of recorded descriptors 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 International Standard also specifies requirements for the processes which are provided within information processing systems to enable information to be interchanged between dif- ferent systems, utilizing recorded flexible disk cartridges as the medium of interchange. For this purpose it specifies the func- tions within systems which are intended to originate or to receive flexible disk cartridges which conform to this Inter- national Standard. This International Standard provides a method for the alloca- tion of space that is independent of the number of files that are recorded on the volume, It also enables the sizes of the record- ed files to be expanded or contracted during processing, sub- ject only to the availability of unused recording space when needed. 1 SIST EN 29293:1997



IS0 9293 : 1987 (E) The contents and organization of the files are not specified by this International Standard and are subject to agreement be- tween the originator 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 Inter- national Standard when all information recorded on it conforms to the requirements of section 2 of this International Standard. 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 conformance with this International Standard if it meets the set of requirements specified in section 3 of 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 met by the system. Conformance with this lnternation Standard does not require conformance with section 4. 3 References IS0 646, Information processing - IS0 7-bit coded character set for information interchange. IS0 7487, Information processing - Data interchange on 130 mm (5.25 in) flexible disk cartridges using modified fre- quency modulation recording at 7 958 ftprad, 1,9 tpmm (48 tpi), on both sides - Part 7: Dimensional, physical and magnetic character- istics. - Part 3: Track format B. IS0 7665, Information processing - File structure andlabelling of flexible disk cartridges for information interchange. IS0 8378, Information processing - Data interchange on 130 mm (5.25 in) flexible disk cartridges using modified fre- quency modulation recording at 7 958 ftprad, 3,8 tpmm (96 tpi), on both sides - Part I: Dimensional, physical and magnetic character- istics. - Part 3: Track format B. IS0 8630, Information processing - Data interchange on 130 mm (5.25 in) high density flexible cartridges using modified frequency modulation recording at 13 262 ftprad, 3,8 tpmm (96 tpi), on both sides - Part 7: Dimensional, physical and magnetic character- istics. 1 ) - Part 3: Track format B for 80 tracks. 1) IS0 8860, Information processing - Data interchange on 90 mm (3.5 in) flexible disk cartridges using modified frequency modulation recording at 7 958 ftprad, 5,3 tpmm (135 tpi), on both sides - Part 7: Dimensional, physical and magnetic character- istics. - Part 2: Track format. 4 Definitions For the purposes of this International Standard the following definitions apply. 4.1 byte: A string of binary digits operated upon as a unit. In this International Standard this term designates an 8-bit byte. 4.2 the data of a sector. data field of a sector: A fixed-length field containing 4.3 data interchange standard : A standard which defines the physical and magnetic characteristics, the recording method, and the track format of a flexible disk cartridge. 4.4 written without error. defective sector: A sector which cannot be read or 4.5 descriptor : A recorded structure containing descriptive information about the volume or a file. 4.6 file: A named collection of information. 4.7 formatting : Writing the control information establishing the physical addresses of sectors on the surfaces of a flexible disk cartridge. 4.8 implementation: A set of processes which enable an information processing system to behave as an originating system, or as a receiving system, or as both types of system. 4.9 initialization : Writing descriptors initially required to be on the FDC, prior to the commencement of general processing or use. 4.10 originating system : An information processing system which can record files on an FDC for the purpose of data interchange with another system. 1) At present at the stage of draft. 2 SIST EN 29293:1997



IS0 9293 : 1987 (E) 4.11 receiving system : An information processing system which can read files from an FDC which has been recorded by another system for the purpose of data interchange. 4.12 sector: That part of a track on a flexible disk cartridge that can be accessed independently of other parts of the track by the magnetic heads of the flexible disk drive. 4.13 track : That part of a flexible disk that can be accessed by a single magnetic head that is stationary while the disk makes a complete revolution. 4.14 user: A person or other entity (for example an applica- tion program) that causes the invocation of the services provid- ed by an implementation. In addition the following definitions apply specifically to section four. 4.15 which all records must have the same length. fixed-length record: A record contained in a file in 4.16 record : Related data treated as a unit of information. 4117 segment : A part of a record. 4.18 segmented record: A record contained in a file in which the records may have different lengths and each record may consist of one or more separate segments. 4.19 variable-length record : A record contained in a file in which the records may have different lengths but a record must not consist of separate segments. 5 Notation4 I this International Standard. 5.1 Decimal and hexadecimal notations Numbers in decimal notation are represented by decimal digits, namely O to 9. Numbers in hexadecimal notation are represented by hexa- decimal digits, namely O to 9 and A to F, shown in parentheses. 5.2 Other notations BP : Byte position within a Descriptor, starting with 1 ZERO : A single bit with the value O ONE: A single bit with the value 1 ip (x) : The integer part of x ceil(x) : The smallest integer that is not less than x rem(x,y) : The remainder of the integer division of x by y, that is, rem(x,y) = x - y x ip(xJy) 5.3 Capital letters Where a word or a group of words is used to designate a specific concept, for example the name of a descriptor field, it is printed with initial capital letters except for prepositions. Section two : Requirements for the medium 6 Volume structure 6.1 Arrangement of data on a flexible disk cartridge 6.1.1 FDC parameters For the purpose of this International Standard the significant parameters of the data interchange standard are shown in table 1. Table 1 FDC parameters Acronym Number of Recordable Sides Number of Tracks per Side Number of Sectors per Track Total Number of Sectors of the FDC Number of Bytes per Data Field of a Sector The values of these parameters shall be obtained from the text of an appropriate data interchange standard (see annex A), 6.1.2 Physical Addresses Each sector shall be identified by a Physical Address compris- ing the Side Number, the Track Number, and the Sector Number. The sides shall be numbered O and 1, tracks shall be numbered starting with 00, and the sectors shall be numbered starting with 1 on each track. / 6.1.3 Logical Sector Number Each sector on a volume shall be identified by a Logical Sector Number. There shall be a one-to-one correspondence between Physical Address and Logical Sector Number. The Logical Sector Numbers shall be assigned in an ascending sequence, beginning with O, starting at sector 1, track 00, side O, continu- ing onto track 00, side 1 (if the FDC is recordable on both sides) and then to track 01, side O, etc. The relation between the Side Number (“1, Track Number (TN), Sector Number (SN) and the Logical Sector Number (LSN) shall be given by the formulae: / LSN = SPT x [HN + (NOS x TN)I + SN - 1 3 SIST EN 29293:1997



IS0 9293 : 1987 (E) SN = rem (rem [LSN, (SPT x NOS)], SPT} + 1 {rem [LSN,(SPT x NOS11 S PT HN = ip 6.1.4 System Area and Data Area The space on an FDC shall be divided into a System Area and a Data Area. The System Area shall be recorded on track 00, side O and track 00. side 1. The System Area shall occupy sectors with the Logical Sector Numbers O to SSA - 1, where SSA is the number of sectors in the System Area (see 6.3.4). The System Area shall contain Descriptors which specify the recording format of the FDC, describe the use of the Data Area, and provide a Directory of the files on the volume. No part of any file shall be contained in the System Area. The Data Area shall occupy sectors with Logical Sector Numbers starting with SSA. Interchange files and supplemen- tary Descriptors (such as Sub-directories) shall be contained in the Data Area. Files not intended for interchange may $so be contained in the Data Area. 6.1.5 Parameters of the Volume Structure This International Standard specifies various types of data structure within the System Area and Data Area. The sizes of these data structures are identified by a set of numerical parameters. These parameters are listed in table 2. Table 2 I Parameter I Acronym Sectors per Cluster Reserved Sector Count Sectors per FAT Root Directory Entries sc RSC SF RDE The values of these parameters for each FDC type are contain- ed in annex A. 6.2 Arrangement of the Data Area 6.2.1 Clusters The Data Area shall be organized into units of allocation called clusters. Each cluster shall consist of the same number of sectors which shall be a power of 2, i.e. 1, 2, 4, 8, . . The number of sectors in each cluster (Sectors per Cluster, SC) shall be as specified in annex A. The data of a cluster shall be recorded in the Data Fields of its constituent sectors. If a cluster comprises more than one sector, the set of Logical Sector Numbers (LSN) of its constituent sectors shall form a consecutive ascending sequence. Each cluster shall be identified by a unique Cluster Number (CN). Cluster Numbers shall be integers, assigned in ascending order starting with 2. Cluster Number 2 shall be assigned to the cluster the first or only sector of which has the Logical Sector Number SSA. Each successive Cluster Number shall be assign- ed to the cluster the sectors of which have the next higher set of LSNs. If the total number of sectors in the Data Area is not a multiple of SC the remaining sectors shall not be used. The Logical Sector Number of the first sector in a cluster shall be related to the Cluster Number by the following formula : LSN [(CN - 2) x SCI + SSA where LSN is the Logical Sector Number; CN is the Cluster Number; SC is the number of sectors per cluster; SSA is the size of the System Area in number of sectors (see 6.3.4). 6.2.2 Status of clusters A status shall be assigned to each cluster, and shall be one of the following : - allocated to a file; - available for allocation; - defective. The status of each cluster shall be identified in the File Alloca- tion Table (FAT) in the System Area. 6.2.2.1 Clusters allocated to a file The clusters allocated to contain a file shall be identified in the FAT. The clust
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