SIST EN 27487-2:1997

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Information processing - Data interchange on 130 mm (5.25 in) flexible disk cartridges using modified frequency modulation recording at 7958 ftprad, 1,9 tpmm (48 tpi), on both sides - Part 2: Track format A (ISO 7487-2:1985)Informationsverarbeitung - Datenaustausch auf 130 mm (5.25 in) Disketten unter Verwendung von modifizierter Wechseltaktschrift mit 7958 Flußwechsel je rad, 1,9 Spuren je mm (48 Spuren je in) auf zwei Seiten - Teil 2: Spurformat A (ISO 7487-2:1985, Ausg. 1)Traitement de l'information - Echange de données sur cartouches a disquette de 130 mm (5,25 in) utilisant un enregistrement a modulation de fréquence modifiée a 7958 ftprad, 1,9 tpmm (48 tpi), sur deux faces - Partie 2: Schéma de piste A (ISO 7487:1985, éd. 1)Information processing - Data interchange on 130 mm (5.25 in) flexible disk cartridges using modified frequency modulation recording at 7958 ftprad, 1,9 tpmm (48 tpi), on both sides - Part 2: Track format A (ISO 7487-2:1985, ed. 1)35.220.21Magnetni diskiMagnetic disksICS:Ta slovenski standard je istoveten z:EN 27487-2:1989SIST EN 27487-2:1997en01-december-1997SIST EN 27487-2:1997SLOVENSKI
STANDARD



SIST EN 27487-2:1997



SIST EN 27487-2:1997



SIST EN 27487-2:1997



International Standard 748712 INTERNATIONAL ORGANIZATION FOR STANDARDIZATION.MEI+t~YHAPO~HAR OPTAH~3AL&lR fl0 CTAH~APTM3ALWlM.ORGANISATlON INTERNATIONALE DE NORMALISATION Information processing - Data interchange on 130 mm (5.25 in) flexible disk cartridges using modified frequency modulation recording at 7 958 ftprad, 1,9 tpmm (48 tpi), on both sides - Part 2 : Track format A Traitemen t de Kinforma tion - khange de donnhes SW cartouches & disquette de 130 mm (5,25 in) utilisant un enregistrement 6 modulation de frequence modifibe & 7 958 ftprad, 1,9 tpmm (48 tpi), sur deux faces - Partie 2 : Schema de Piste A First edition - 1985-03-15 UDC 681.327.63 Ref. No. ISO 7487/2-1985 (E) Descriptors : data processing, information interchange, data recording devices, magnetic disks, flexible disks, track formats, specifications. Price based on 13 pages SIST EN 27487-2:1997



Foreword ISO (the International Organization for Standardization) is a worldwide federation of national Standards bodies (ISO member bedies). The work of preparing International Standards is normally carried out through ISO technical committees. Esch 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 ISO Council. They are approved in accordance with ISO procedures requiring at least 75 % approval by the member bodies voting. International Standard ISO 7487/2 was prepared by Technical Committee ISO/TC 97, lnforma tion processing s ystems. 0 International Organkation for Standardkation, 1985 Printed in Switzerland ii SIST EN 27487-2:1997



Contents Page 0 Introduction . 1 Scope and field of application . 2 Conformance . 3 References . 4 Trackformat . 4.1 General requirements . 4.2 Track layout after the first formatting for track 00, side 0. . 4.3 Track layout after the first formatting for all tracks other than track 00, side0 . 4.4 Track layout of a recorded flexible disk for data interchange . Annexes A EDC implementation . B Procedure and equipment for measuring flux transition spacing . C Data seoarators for decoding MFM recordinq . 5 6 9 IO 13 . . . Ill SIST EN 27487-2:1997



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INTERNATIONAL STANDARD ISO 7487/2-1985 (E) Information processing - Data interchange on 130 mm (5.25 in) flexible disk cartridges using modified frequency modulation recording at 7 958 ftprad, 1,9 tpmm (48 tpi), on both sides - Part 2 : Track format A 0 Introduction ISO 7487 specifies the characteristics of 130 mm (5.25 in) flex- ible disk cartridges recorded at 7 958 ftprad, 1,9 tpmm (48 tpi), on both sides using modified frequency modulation (MFM) recording. ISO 7487/1 specifies the dimensional, physical, and magnetic characteristics of the cartridge so as to provide physical inter- changeability between data processing Systems. Together with the labelling scheme specified in ISO 7665, ISO 7487/1 and ISO 7487/2 provide for full data interchange between data processing Systems. ISO 7487/3 specifies an alternative track format for data inter- Change. 1 Scope and field of application This part of ISO 7487 specifies the quality of recorded Signals, the track layout, and a track format to be used on such a flex- ible disk cartridge, which is intended for data interchange between data processing Systems. NOTE - Numeric values in the SI and/or Imperial measurement System in this International Standard may have been rounded off and therefore are consistent with, but not exactly equal to, each other. Either System may be used, but the two should be neither intermixed nor re-converted. The original design of this part of ISO 7487 was made using SI units. 2 Conformance A flexible disk cartridge shall be in conformance with ISO 7487 when it meets all the requirements either of Parts 1 and 2 or of Parts 1 and 3 of ISO 7437. 3 References ISO 646, Information processing - ISO 7-bit coded Character set for informa tion in terchange. ISO 2022, Information processing - ISO 7-bit and 8-bit coded Character sets - Code extension techniques. ISO 4873, Information processing - ISO 8-bit Code for infor- ma tion in terchange - Structure and rules for implemen- ta tion. ISO 7437, lnforma tion 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 : Dimensionad ph ysical and magnetic characteristics. Part 3 : Track format B. ISO 7665, lnforma tion processing - File structure and labelling of flexible disk cartridges for informa tion in terchange. 4 Track format 4.1 General requirements 4.1.1 Mode of recording 4.1.1.1 Track 00, side 0 The mode of recording shall be two-frequency where the Start of every bit cell is a clock flux transition. A ONE is represented by a data flux transition between two clock flux transitions. Exceptions to this are defined in 4.1.12. 4.1.1.2 All tracks other than track 00, side 0 The mode of recording shall be Modified Frequency Modula- tion (MFM) for which the conditions are a) a flux transition shall be written at the centre of each bit cell containing a ONE; b) a flux transition shall be written at each cell boundary between consecutive bit cells containing ZERO’s. 1 SIST EN 27487-2:1997



ISO 7487/2-1985 (El Exceptions to this are defined in 4.1.12. 4.1.2 Track location tolerante of the recorded flexible disk cartridge The centrelines of the recorded tracks shall be within + 0,085 mm (0.003 3 in) of the nominal positions, over the range of operating environment specified in ISO 7487/1. This tolerante corresponds to twice the Standard deviation. 4.1.3 Recording offset angle At the instant of writing or reading a magnetic transition, the transition may have an angle of 0’ + 18’ with the radius. This tolerante corresponds to twice the Standard deviation. 4.1.4 Density of recording 4.1.4.1 The nominal density of recording shall be 7 958 ftprad. The nominal bit cell length for track 00, side 0 is 251 prad, and for all the other tracks it is 1255 prad. 4.1.4.2 The long-term average bit cell length shall be the average bit cell length measured over a sector. lt shall be within * 3,5 % of the nominal bit cell length. 4.4.4.3 The short-term average bit cell length, referred to a particular bit cell, shall be the average of the lengths of the preceding eight bit cells. It shall be within + 8 % of the long- term average bit cell length. 4.1.5 Flux transition spacing The instantaneous spacing between flux transitions may be in- fluenced by the reading and writing process, the bit sequence recorded (pulse crowding effects), and other factors. The lo- cations of the transitions are defined as the locations of the peaks in the Signal when reading. Tests should be carried out using a peak-sensing amplifier. 4.1.5.1 Flux transition spacing for track 00, side 0 (sec figure 1) 4.1.5.1.1 The spacing between two clock flux transitions sur- rounding a data flux transition or between two data flux tran- sitions surrounding a clock flux transition shall be between 90 % and 140 % of the nominal bit cell length. 4.1.5.1.2 The spacing between two clock flux transitions not surrounding a data flux transition or between two data flux transitions surrounding a missing clock flux transition shall be between 60 % and 110 % of the nominal bit cell length. 4.1.5.1.3 The spacing between a data flux transition and the preceding clock flux transition (when not missing) or between a clock flux transition and the preceding data flux transition (when not missing) shall be between 45 % and 70 % of the nominal bit cell length. 4.1.5.2 Flux transition spacing for all tracks other than track 00, side 0 (sec figure 2). 4.1.5.2.1 The spacing between the flux transitions in a se- quence of ONE’s shall be between 80 % and 120 % of the short-term average bit cell length. 4.1.5.2.2 The spacing between the flux transition for a ONE and that between two ZERO’s preceding or following it shall be between 130 % and 165 % of the short-term average bit cell length. 4.1.5.2.3 The spacing between the two ONE flux transitions surrounding a ZERO bit cell shall lie between 185 % and 225 % of the short-term average bit cell length. 4.1.6 Average Signal amplitude For each side the average Signal amplitude on any non- defective track (sec ISO 7487/1) of the interchanged flexible disk cartridge shall be less than 160 % of SRAlfand more than 40 % of SRAzY 4.1.7 Byte A byte is a group of eight bit-positions, identified B 1 to B8, with B8 the most significant and recorded first. The bit in each Position is a ZERO or a ONE. - 90°hi-0 140%- - - 90 O/o to 140% --60% to 110% - - -- - Figure 1 l 2 SIST EN 27487-2:1997



ISO 7487/2-1985 (El I \ r \ b 80% to 120°/o 130% to 165'/0 130°/o to 165'/0 185O/o to 225% Figure 2 4.1.8 Seetor All tracks are divided into 16 sectors. 4.1.9 Cylinder A pair of tracks, one on each side, having the same track number. 4.1 .lO Cylinder number The cylinder number shall be a two-digit number identical with the track number of the tracks of the cylinder. 4.1.11 Data capacity of a track The data capacity of track 00, side 0 shall be 2 048 bytes. The data capacity of all tracks other than track 00, side 0 shall be 4 096 bytes. 4.1.12 Hexadecimal notation Hexadecimal notation shall be used hereafter to denote the following bytes : (00) for (88 to Bl) = 00000000 (01) for (B8 to Bl) = 00000001 (FF) for (B8 to Bl) = 11111111 (FE)” for (B8 to BI) = 11111110 where the clock transitions of B6, B5 and B4 are missing (FB)” for (B8 to Bl) = 11111011 where the clock transitions of B6, B5 and B4 are missing (F8)” for (B8 to BI) = 11111000 where the clock transitions of B6, B5 and B4 are missing (4E) for (B8 to BI) = 01001110 (FE) for (B8 to Bl) = 11111110 FB) for (B8 to Bl) = 11111011 F8) for (B8 to Bl) = 11111000 Al)” for (B8 to Bl) = 10100001 where the boundary transition between B3 and B4 is miss- ing. 4.1.13 Error detection characters (EDC) The two EDC-bytes are hardware generated by shifting serially the relevant bits, specified later for each part of the track, through a 16-bit shift register described by Xl6 + x12 + x5 + 1 (See also annex A.) 4.2 Track layout after the first formatting for track 00, side 0 After first formatting, there shall be 16 usable sectors on the track. The layout of the track shall be as shown in figure 3. During formatting the rotational Speed of the disk, averaged index to index, shall be 300 + 6 r/min. 4.2.1 Index gap At nominal density, this field shall comprise 16 (FFLbytes. Writing the index gap is started when the index hole is detected. Any of the first 8 bytes may be ill-defined due to subsequent overwriting. SIST EN 27487-2:1997



ISO 7487/2-1985 (E) INDEX SECTOR IDENTIFIER FIRST DATA LAST DATA TRACK GAP IDENTIFIER GAP DATA BLOCK DATA BLOCK BLOCK GAP BLOCK GAP GAP c LL 1st Seetor Figure 3 --P 16th Seetor - - - -4 4.2.2 Seetor identifier 4.2.2.2.4 EDC This field shall be as given in table 1. These two bytes shall be generated as defined in 4.1 .l3 using the bytes of the sector identifier starting with the (FE)*-byte (sec 4.2.2.1) of the identifier mark and ending with the 4th byte tsee 4.2.2.2.3) of the sector address. Table 1 Identifier mark Seetor identifier Address identifier 6 bytes (00) 4.2.2.1 Identifier mark This field shall comprise 7 bytes : 6 (OO)-bytes 1 (FE)*-byte 4.2.2.2 Address identifier This field shall comprise 6 bytes. 4.2.2.2.1 Track address This field shall comprise two bytes : a) Cylinder address (C) This field shall specify in binary notation the cylinder ad- dress. lt shall be (00) for all sectors. b) Side number (Side) This field shall specify the side of the disk. lt shall be (00) for all sectors. 4.2.2.2.2 Seetor number (SI The 3rd byte shall specify in binary notation the sector number from 01 for the 1st sector to 16 for the last sector. The 16 sectors shall be recorded in the natura1 Order : 1, 2, 3, . . . . 15, 16 4.2.2.2.3 4th byte of the sector address The 4th byte shall always be a (OO)-byte. 4.2.3 Identifier gap This field shall comprise 11 initially recorded (FFLbytes. 4.2.4 Data block This field shall be as given in table 2. Table 2 Data block Data mark Data field 6 bytes 1 byte 128 bytes (00) (W” 4.2.4.1 Data mark * EDC 2 bytes This field shall comprise 6 (OO)-bytes 1 (FB)*-byte 4.2.4.2 Data field This field shall comprise 128 bytes. No requirements are implied beyond the correct EDC for the content of this field (sec also 4.4.4.2.4.2). 4.2.4.3 EDC These two bytes shall be generated as defined in 4.1.13 using the bytes of the data block starting with the 7th byte of the data mark (see 4.2.4.1) and ending with the last byte of the data field (see 4.2.4.2). 4.2.5 Data block gap This field shall comprise 27 initially recorded (FF)-
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