EN 25652:1991

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Information processing - 9-track, 12.7 mm (0.5) wide magnetic tape for information interchange - Format and recording, using group coding at 246 cpmm (6250 cpi) (ISO 5652:1984)Informationsverarbeitung - 9-Spur-Magnetband 12,7 mm (0,5 in) für den Informationsaustausch - Format und Aufzeichnung in GCR-Verfahren mit 246 Zeichen/mm (6250 Zeichen/in) (ISO 5652:1984, Ausg. 2)Traitement de l'information - Bande magnétique a 9 pistes de 12,7 mm (0,5 in) de large pour l'échange d'information - Format et enregistrement utilisant des codages de groupe a 246 cpmm (6250 cpi) (ISO 5652:1984, éd. 2)Information processing - 9-track, 12.7 mm (0.5) wide magnetic tape for information interchange - Format and recording, using group coding at 246 cpmm (6250 cpi) (ISO 5652:1984, ed. 2)35.220.22Magnetni trakoviMagnetic tapesICS:Ta slovenski standard je istoveten z:EN 25652:1991SIST EN 25652:1997en01-december-1997SIST EN 25652:1997SLOVENSKI
STANDARD



SIST EN 25652:1997



SIST EN 25652:1997



SIST EN 25652:1997



International Standard INTERNATIONAL ORGANIZATION FOR STANDARDIZATIONWlE)I(~YHAPO~HAfl OPTAHM3AWlR ilO CTAH~APTbl3AL&lM~RGANlSATlON INTERNATIONALE DE NORMALISATION Information processing - g-Track, 12,7 m’rn (0.5 in) wide magnetic tape for information interchange - Format and recording, using group coding ,at 246 cpmm (6 250 cpi) Traitemen t de l’in forma tion - Bande magnhtique ;i 9 pistes de 12,7 mm (0,5 in) de large pour l’kchange d’information - Format et enregistrement utilisant des codages de groupe & 246 cpmm (6 250 cpi) Second edition - 1984-12-01 UDC 681.3.04 : 681.32764 Ref. No. IS0 5652-1984 (E) Descriptors : data processing, information interchange, magnetic tapes, g-tracks, definitions, operating requirements, magnetic recording, data representation, block format, transportation. Price based on 15 pages SIST EN 25652:1997



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 5652 was prepared by Technical Committee ISO/TC 97, Information processing systems. IS0 5652 was first published in 1983. This second edition cancels and replaces the first edition, of which sub-clause B.3.2 of annex B has been technically revised. 0 International Organization for Standardization, 1984 Printed in Switzerland SIST EN 25652:1997



Contents Page 1 1 1 2 2 4 4 5 7 8 8 9 11 12 13 1 2 3 4 5 6 7 8 9 10 11 12 13 Scope and field of application . References . Definitions. . Operating and transportation conditions . Recording . Tracks . Data representation . Data formatting . Recording of groups on tape . Control sub-groups. . Storageblock . Tape format . . . Interchange criteria . . . Annexes A Transportation. . . . . . . . . . . . . . . . . . . . . . . B Measurement of flux transition spacing . I . . . . , . . . . . . . . . . . . . . . . . . . . . I . . . . . . . I . . . . . . . . . . . . . . . 8 , . . . . . . . . . . III SIST EN 25652:1997



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INTERNATIONAL STANDARD IS0 5652-1984 (E) Information processing - g-Track, 12,7 mm (0.5 in) wide magnetic tape for information interchange - Format and recording, using group coding at 246 cpmm (6 250 cpi) 1 Scope and field of application 3 Definitions This International Standard specifies a format and recording standard for g-track, 12,7 mm (0.5 in) magnetic tape to be used for data interchange between information processing systems, communication systems, and associated equipment utilizing the ‘/-bit coded character set (see IS0 646), its extension in IS0 2022 where required, and the 8-bit coded character set (see IS0 4873). Magnetic labelling for use on magnetic tape is the subject of IS0 1001. The magnetic tape and reel to be used shall conform to IS0 1864. For the purpose of this International Standard, the following definitions apply. 31 . magnetic tape : A tape which will accept and retain magnetic signals intended for input, output and storage pur- poses on computers and associated equipment. NOTE - Numeric values in the SI and/or Imperial measurement system in this International Standard may have been rounded 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 reconverted. The original design was made using the Imperial measurement system. 3.2 reference tape : A tape which has been selected for given properties for use in calibration. . 3.3 secondary reference tape : A tape intended for routine calibrating purposes whose performance is known and is stated in relation to that of a reference tape. 2 References IS0 646, Information processing - /SO 7-bit coded character set for information interchange. IS0 1001, Information processing - Magnetic tape labelling and file structure for information interchange. IS0 1864, Information processing - Unrecorded 12,7 mm (0.5 in) wide magnetic tape for information interchange - 32 ftpmm (800 ftpi) NRZI, 126 ftpmm (3 200 ftpi) phase en- coded and 356 ftpmm (9 042 ftpi), NRZI. IS0 2022, Information processing - IS0 7-bit and 8-bit coded character sets - Coded extension techniques. 1) IS0 4873, Information processing - 8-bit code for information interchange - S true ture and rules for implementation. 2) 3.4 signal amplitude reference tape : A reference tape selected as a standard for signal amplitude. NOTE - A master standard (computer amplitude reference) has been established at the US National Bureau of Standards (NBS) based on reference tapes and heads. Secondary signal amplitude reference tapes are available from the NBS3) under the part number SRM 6250. 3.5 typical field : The minimum recording field which, when applied to a magnetic tape, causes a signal output equal to 95 % of the maximum signal amplitude at the specified physical recording density. 3.6 reference field : The typical field of the signal amplitude reference tape at 356 ftpmm (9 042 ftpi). 1) At present at the stage of draft. (Revision of IS0 2022-1982.) 2) At present at the stage of draft. (Revision of IS0 4873-1979.) 3) Office of Standard Reference Materials, Room B 311, Chemistry Building, National Bureau of Standards (NBS), Washington, D.C. 20234, USA. SIST EN 25652:1997



IS0 56524984 (E) 3.7 standard reference amplitude : The average peak-to- peak signal amplitude derived from the signal amplitude reference tape on the NBS measurement system, or equivalent, under the recording conditions specified in IS0 1864. 38 . reference edge : The edge furthest from an observer when a tape is lying flat with the magnetic surface uppermost and the direction of movement for recording is from left to right. 4 Operating and transportation conditions 39 . in contact : An o magnetic surface of a tape peration condition in which the is in contact with a magnetic head. 4.1 Operating environment Tapes used for data following condi tions interchange shall be operated under the 3.10 track : A longitudinal area on a ta series of magnetic signals may be recorded. pe along which a - temperature : 16 to 32 OC (60 to 90 OF); 3.11 track row : N ine transversely rel n which bits are recorded. ated locations (one in 1 i - relative humidity: 20 to 80 %; - wet bulb temperature : not greater than 26 OC (78 OF). 3.12 position of flux transition : The point which exhibits the maximum free-space flux density normal to the tape sur- face. Conditioning before operating : If a tape has been exposed dur- ing storage and/or transportation to conditions outside the above values, it should be conditioned for a period of 2 to 12 h. depending on the extent of exposure. 3.13 physical recording density : The number of recorded flux transitions per unit length of track (ftpmm or ftpi). 4.2 Transportation 3.14 data density : The number of per uni t length of tape (cpmm or cpi). data characters Responsibility for ensuring that adequate precautions against damage are taken during shipment shall lie with the sender (see annex A). 3.15 skew : The maximum longitudinal deviation in the placement of bits within a row. 4.3 Wind tension For interchange, the tape winding tension shall be between 2 N and 3,6 N (7 to 13 ozf). 3.16 ECC character and correction within a A character ata group. used for error detection d 3.17 auxiliary CRC character : A character used for error detection within the data part of a block. 5 Recording 5.1 Method of recording The “non return to zero mark” (NRZI ) method of recording shall be used where a ONE is represented by a change of direc- tion of longitudinal magnetization. 3.18 CRC character : A character used for error detection within a complete block. 3.19 preamble : A pattern of signals marking the beginning of each storage block, used primarily for electronic syn- chronization. 5.2 Density of recording The nominal density shall be 356 ftpmm (9 042 ftpi). Other nominal densities used hereafter for specific measurements shall be 3.20 postamble : A pattern of signals marking the end of each storage block. 178 ftpmm (4 521 ftpi) 3.21 density identification area (ID burst) : A burst of recording at the beginning of a tape identifying the use of the group-coded-recording method. 119 ftpmm (3 014 ftpi). 2 SIST EN 25652:1997



IS0 56524984 (El 5.3 Average flux transition spacings The following measurements shall be made after interchange using a tape recorded at a density of 178 ftpmm (4 521 ftpi). The nominal flux transition spacing at this density shall be 5,618 pm (221.2 vin) subject to the following variations. 5.3.1 The long term average (static) flux transition spacing shall be within + 4 % of the nominal spacing. This average shall be measured over a minimum of 5 x 105 successive flux transitions. 5.3.2 The short term average (dynamic) flux transition spacing, when referred to a particular flux transition spacing, is the average of that flux transition spacing and the preceding flux transition spacing. The short term average flux transition spacing shall be within the limits of + 6 % of the long term average flux transition spacing. In addition, the rate of change of the short term average flux transition spacing shall not exceed 0,2 % per flux transition spacing. 5.4 Instantaneous flux transition spacings The instantaneous spacing between flux transitions may be influenced by the reading and writing processes, the pattern recorded (pulse crowding effects) and other factors. Instantaneous spacings between flux transitions shall meet the following conditions, when tested on the reference read chain (see annex B). 5.4.1 At the nominal maximum density of 356 ftpmm (9 042 ftpi) the spacing dl between successive flux transitions shall be be- tween 48 % and 52 % of the corresponding short term average flux transition spacing determined at 178 ftpmm (4 521 ftpi). I d _ I,, d I- d 1 clw d, d, 5.4.2 In a sequence of flux transitions defined by the bit pattern 1110011100. ., the average displacement of the spacing of the flux transitions on either side of a reference transition, from that reference transition, shall be not more than + 28 % from the average spacing of flux transitions at 356 ftpmm (9 042 ftpi). 1 0 0 Crosses denote reference transitions. I,28 dl > average d5 > 0,72 dl I,28 d, > average d2 > 0,72 dl 1,28 d, > average d3 > 0,72 dl 1,28 d, > average de > 0,72 dl The tolerances of long term average spacing and short term average spacing (see 5.3.1 and 5.3.2) are included in this deviation. The average distance dG between actual consecutive reference flux transitions in a sequence defined by the bit pattern 1110011100. . and the calculated distance 5dl, of six flux transitions at nominal maximum density of 356 ftpmm (9 042 ftpi) shall not differ by more than 6 % of dl. 5,06 d, > average dG > 4,94 dl SIST EN 25652:1997



IS0 5652-1984 (El 5.5 Skew 6 Tracks No flux transition shall be displaced by more than 16,86 pm (664 pin) from any other flux transition in the same row. This displacement shall be measured as the distance between perpendiculars to the reference edge through the said flux tran- sitions. 6.1 Number of tracks There shall be nine tracks. 6.2 Track identification 5.6 Signal amplitude Tracks shall be numbered consecutively beginning at the reference edge with track 1. 5.6.1 Standard reference amplitude The standard reference amplitude is the average peak-to-peak signal amplitude derived from the signal amplitude reference tape on the qualified measurement system at the density of 356 ftpmm (9 042 ftpi) and the recording current IR = k x I. (see IS0 1864). 6.3 Track positions The distance from the centrelines of the tracks to the reference edge shall be : Track 1 : 0,74 + 0,08 mm (0.029 + 0.003 in) Track 2 : 2,13 + 0,08 mm (0.084 + 0.003 in) Track 3 : 3 53 4193 _ + 0,08 mm (0.139 + 0.003 in) Track 4 : If: 0,08 mm (0.194 + 0.003 in) Track 5 : 6,32 + 0,08 mm (0.249 ?I 0.003 in) Track 6 : 7,72 + 0,08 mm (0.304 + 0.003 in) Track 7 : 9,12 + 0,08 mm (0.359 + 0.003 in) Track 8 : lo,52 + 0,08 mm (0.414 + 0.003 in) Track 9 : 11,91 + 0,08 mm (0.469 + 0.003 in) The signal amplitude shall be averaged over a minimum of 4 000 flux transitions and shall be measured on the read-while- write pass. The reference current If is the current which produces the reference field (see 3.6). 5.6.2 Average signal amplitude 5.6.2.1 The average peak-to-peak signal amplitude of the interchanged tape at 356 ftpmm (9 042 ftpi) shall not deviate by more than + 50 % from the standard reference amplitude. 6.4 Track width The width of a written track shall be : I,09 mm min. (0.043 in min.) 5.6.2.2 The average peak-to-peak signal amplitude at 119 ftpmm (3 014 ftpi) shall be less than five times the standard reference amplitude. 7 Data representation 5.6.2.3 Averaging shall be done over a minimum of 4 000 flux transitions, which for the interchange tape may be segmented into blocks. Averaging shall be done on the first-read pass after interchange. The characters shall be represented by means of the 7-bit coded character set (see IS0 646) or the 8-bit coded character set (see IS0 4873) or, where required, of an extension of the 7-bit coded character set (see IS0 2022). The bit-to-track allocation shall be as follows : 5.6.3 Minimum signal amplitude A tape to be interchanged shall contain no flux transition in more than one track since the last MARK 1 control sub-group, the base-to-peak amplitude of which is less than 15 % of half the standard reference amplitude. 7.1 7-bit coded characters Binary weight Bit designation b, b2 b3 b4 b5 b6 b7 - P Track 281935674 5.7 Erasure Track 7 shall always be recorded with bit ZERO. 5.7.1 When erased, the rim end of the erased area of the tape shall be magnetized so that it is a North-seeking pole. 7.2 8-bit coded characters 5.7.2 The full width of the tape shall be DC erased in the direction specified. in 5.7.1. Binary weight 20 2’ 22 23 24 25 26 27 - Bit designation bbbbbbbbP 12345678 Track 281935674 Bit P in track 4 shall be the parity bit. The parity shall be odd. 5.7.3 The tape shall be erased so that the residual signal shall not exceed 4 % of the standard reference amplitude. 4 SIST EN 25652:1997



IS0 56524984 (El 8 Data formatting - in positions 1 to 6, not occupied by a data byte, a pad- ding character [byte (00) with odd parity]; Prior to recording, the data shall be arranged in groups com- pleted with computed check characters (see 8.4). These data groups shall be in turn arranged in a given sequence together with groups of control characters. The data and control character groups so arranged are then recorded on the tape ac- cording to a specific coding scheme (see clause 9). - in position 7, an auxiliary CRC character; - in position 8, an ECC character. 8.3 CRC group (see figure below) 8.1 Data groups After the residual group, a CRC group shall be formed compris- ing A data group shall comprise 8 bytes as follows : - in position 1 : byte (00) with odd parity if the number of preceding data groups is even, or the CRC character if the number of preceding data groups is odd; - in positions 1 to 7, seven data bytes; - in position 8, an ECC character. - in positions 2 to 6, the CRC character; 8.2 Residual group - in position 7, the residual character; A residual group shall be a group comprising - in positions 1 to 6, the remaining data bytes, if any; - in position 8, an ECC character. 8765 4321 8 765 4321 8765 4321 - Group position EAOO ;OODD EAOO lOODD EAOO IOODD EDDD ;DDDD EDDD IDDDD EDDD IDDDD PPPP ’ PPPP ‘EDDD [DDDD EDDD IDDDD EDDD IDDDD EDDD IDDDD EDDD !DDDD 1 ERCC CCC0 ERCC ;CCCO ERCC lCCC0 PPCC MCCP ERCC ‘CCC0 ERCC 1 CCC0 ERCC I CCC0 ERCC ‘CCC0 ERCC I CCC0 2 0 4 Parity 5 6 7 PAPP ] PPPP EAOO ;OODD EAOO ‘OODD EAOO lOODD EAOO lOODD EAOO ~~ODD 8 3 CRC WO”P Residual Data WO”P group Binary Track weight No. Time NOTE - The line of bits corresponding to each track number shown will then be group coded and the resulting bit stream will then be recorded on the tape in the corresponding track. (see clause 91, SIST EN 25652:1997



IS0 5652-1984 (El The coefficients shall be the bits in each data byte. 8.4 Check characters The coefficients of polynomial MI shall be the bits of the byte in position 1 of the first data group, those of polynomial M2 shall be the bits of the byte in position 2, etc., up to M, where II is the number of data bytes within the block. 8.4.1 ECC character The ECC character shall be calculated separately for each group (data group, residual group and CRC group). In each case, 7 polynomials D1 to D, shall be formed, the coefficients of which shall be the 8 bits of each byte in positions 1 to 7. The coeffi- cients of polynomial D1 shall be the bits in position 1, those of polynomial D2 shall be the bits in position 2, etc. The parity bit in track 4 shall not be part of the ECC character generation. These bits shall be allocated to the polynomials as follows : Bit from track is coefficient of 1 x0 I 5 I X’ I These bits shall be allocated to the polynomials as follows : X2 I Bit from track I is coefficient of I I 4 I x3 I I 7 2 r X’ X5 6 fi 3 I 7 I X7 I 9 r The auxiliary CRC character shall be obtained as follows. An asymmetrical polynomial IV shall be computed X7 I N= C (xMj) (mod HI - - The ECC character shall be obtained from the coefficients of polynomial E computed as follows : E= C (xiDj) (mod G) where i= 7 to 1 j= 1 to 7 G= $+x3+x4+x5+ti where i= n to 1 j= 1 to n H=xo+x*+fi+fl All arithmetic operations shall be (mod 2). All arithmetic operations shall be (mod 2). A polynomial (x0 + ~1 + $ + x7 +x8) shall be combined by means of an exclusive OR operation with N in the correspond- ing bit positions. The bits of the ECC character shall be the coefficients of the resulting polynomial : The coefficients of the resulting polynomial shall be the bits of the auxiliary CRC character according to the following alloca- tion : 1 the coefficient of I X’ I 2 I x4 I In track the coefficient of X7 I I 1 x0 I 2 x4 3 x-6 5 x3 6 x6 4 x3 5 X’ 1- I I 9 X5 In track 4, an odd parity bit P shall be inserted. I 7 I X7 1 X2 I 9 8.4.2 Auxiliary CRC character The auxiliary CRC character shall have odd parity. If the aux- iliary CRC character obtained has even parity, the bit in track 4 shall be inverted to obtain odd parity. The auxiliary CRC character shall be calculated from all the data bytes within the storage block considered as g-bit bytes by in- clusion of their parity bit P. Polynomials Mj shall be formed. 6 SIST EN 25652:1997



IS0 5652-1984 (E) 8.4.3 CRC character 8.4.4 Residual character The CRC character shall be calculated from all the previous characters within the block (data, padding characters, auxiliary CRC, and the padding character, if any, in position 1 of the CRC group) considered as g-bit bytes by inclusion of their par- ity bit, but excluding all the ECC characters in position 8 of the data groups and of the residual group. Polynomials Mj shall be formed, the coefficients of which are the bits in each byte. The coefficients of polynomial Ml shall be the bits of the byte in position 1 of the first data group, those of polynomial M2 shall be the bits of the byte in position 2, etc., up to Mn for
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