1、BRITISH STANDARD BS 7080-2: 1989 ISO 8462-2: 1986 Guide to Construction and use of6.30mm(0.25in) magnetic tape cartridge for data interchange, using GCR recording at394ftpmm (10 000ftpi),39cpmm (1000cpi) Part2: Streaming mode ISO title: Information processing Data interchange on6,30mm(0.25in) magnet
2、ic tape cartridge using GCR recording at394ftpmm(10 000ftpi),39cpmm(1 000cpi) Part2: Streaming mode UDC 681.327.636:006.015.3:.004.12:681.3.015:001.4:620.1BS7080-2:1989 This British Standard, having been prepared under the directionof the Information Systems Technology Standards Policy Committee, wa
3、s published under the authority of the Board ofBSI and comes into effect on 30 June1989 BSI 01-2000 The following BSI references relate to the work on this standard: Committee reference IST/4 Draft for comment 84/63330 DC ISBN 0 580 17188 4 Committees responsible for this British Standard The prepar
4、ation of this British Standard was entrusted by the Information Systems Technology Standards Policy Committee (IST/-) to Technical Committee IST/4, upon which the following bodies were represented: Association for Payment Clearing Services British Computer Society British Telecommunications plc Busi
5、ness Equipment and Information Technology Association Department of Trade and Industry (National Physical Laboratory) HM Customs and Excise HM Treasury (Central Computer and Telecommunications Agency) Institute of Administrative Management Institute of Quality Assurance Institution of Electrical Eng
6、ineers Institution of Electronic and Radio Engineers Institution of Mechanical Engineers National Computing Centre Ltd. Post Office Amendments issued since publication Amd. No. Date of issue CommentsBS7080-2:1989 BSI 01-2000 i Contents Page Committees responsible Inside front cover National foreword
7、 ii 1 Scope and field of application 1 2 Conformance 1 3 References 1 4 Hexadecimal notation 1 5 Reference plane 1 6 Track geometry 2 7 Recording 2 8 Erasure 5 9 Recording offset angle 5 10 Use of tracks 5 11 Coded representation of the data 6 12 Recording of coded characters on the tape 7 13 Track
8、format 8 14 End of recorded data 11 15 Re-writing operations 11 16 Updating operations 12 17 Reading operations 12 Annex Example of writing operations 13 Figure 1 3 Figure 2 4 Figure 3 4 Figure 4 6 Table 1 7 Publications referred to Inside back coverBS7080-2:1989 ii BSI 01-2000 National foreword Thi
9、s Part of BS7080, prepared under the direction of the Information Systems Technology Standards Policy Committee, is identical with ISO8462-2:1986 “Information processing Data interchange on6,30mm(0.25in) magnetic tape cartridge using GCR recording at394ftpmm(10000ftpi),39cpmm(1000cpi) Part2: Streami
10、ng mode” published by the International Organization for Standardization (ISO). The purpose of this standard is to define those characteristics necessary for successful data interchange using magnetic tape cartridges. The information contained is intended as a guide to writing complete specification
11、s for manufacture, purchasing and/or testing. The text of the International Standard does not accord with the recommendations for drafting product specifications given in the ISO Directives, or in BS0-3, but the BSI Technical Committee considers the text is useful as a guide when cartridges are bein
12、g described or specified. For this reason this British Standard has a different title from the International Standard; it is issued as a British Standard guide and it should only be used as such. It should not be used on its own as a British Standard product specification and, in particular, no clai
13、ms of compliance with this British Standard should be made. 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 are not identical with those used in British
14、 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. A British Standard does not purport to include all the necessary provisions
15、 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. Cross-references International Standard Corresponding British Standard ISO646:1983 BS4730:1985 Specification for UK7
16、-bit coded character set (Identical, exercising national options) ISO2022:1986 BS6856:1987 Specification for code extension techniques for United Kingdom7-bit and8-bit coded character sets (Identical) ISO4873:1986 BS6006:1987 Specification for structure and rules for implementation of UnitedKingdom8
17、-bit coded character set (Identical) ISO8462-1:1986 BS7080 Guide to construction and use of6.30mm(0.25in) magnetic tape cartridge for data interchange using GCR recording at394ftpmm(10000ftpi),39cpmm(1000cpi) Part1:1989 Mechanical, physical and magnetic properties (Identical) Summary of pages This d
18、ocument comprises a front cover, an inside front cover, pages i and ii, pages1 to14, 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.BS7080-2:1
19、989 BSI 01-2000 1 1 Scope and field of application ISO8462 specifies the characteristics of a tape cartridge loaded with magnetic tape6,30mm(0.25in) wide intended for digital recording at physical recording densities of252ftpmm(6400ftpi) and394ftpmm(10000ftpi). ISO8462-1 specifies the mechanical, ph
20、ysical and magnetic properties of a6,30mm(0.25in) wide magnetic tape cartridge and methods for testing the surface quality of the tape. It also specifies the environmental conditions under which the cartridge shall be tested and operated, and recommends conditions for storage. This part of ISO8462 s
21、pecifies a recording method and a data format intended for use in the streaming mode of operation. Two alternative track formats are specified: a4-track format, and a9-track format. ISO8462-1 and ISO8462-2 provide for the physical interchange of cartridges between data processing systems, and specif
22、y a data format. A labelling standard for tape cartridges used in the streaming mode is under study. The availability of such a labelling standard will provide for full data interchange between data processing systems. NOTENumeric values in the SI and/or Imperial measurement system in this part of I
23、SO8462 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 reconverted. The original design was made using the Imperial measurement system. 2 Conformance A6,30mm(0.25 in) wide magne
24、tic tape cartridge shall be in conformance with ISO8462 if it meets either all mandatory requirements of both ISO8462-1 and ISO8462-2 specified for the4-track format or all mandatory requirements of both ISO8462-1 and ISO8462-2 specified for the9-track format. The two formats shall not exist on the
25、same cartridge. In addition the code used shall conform with one of the codes specified in the documents referenced in clause3. 3 References ISO646, Information processing ISO7-bit coded character set for information interchange. ISO2022, Information processing ISO7-bit and8-bit coded character sets
26、 Code extension techniques. ISO4873, Information processing 8-bit coded character set for information interchange. ISO8462-1, Information processing Data interchange on6,30mm(0.25in) magnetic tape cartridge using GCR recording at394ftpmm(10000ftpi),39cpmm(1000cpi) Part1:Mechanical, physical and magn
27、etic properties. 4 Hexadecimal notation Hexadecimal notation is used hereafter to denote the following bytes: (00) for (B8 to B1) =00000000 (01) for (B8 to B1) =00000001 (02) for (B8 to B1) =00000010 (03) for (B8 to B1) =00000011 (04) for (B8 to B1) =00000100 (05) for (B8 to B1) =00000101 (06) for (
28、B8 to B1) =00000110 (07) for (B8 to B1) =00000111 5 Reference plane The Reference Plane shall be the top of the base plate (plane B in ISO8462-1). The Reference Edge shall be that edge of the tape which is nearer to the top of the base plate. The location of the centrelines of the tracks is referred
29、 to the Reference Plane.BS7080-2:1989 2 BSI 01-2000 6 Track geometry 6.1 Track location The positions of the nine tracks are defined by specifying the distance of their centrelines from the Reference Plane (seeFigure 1). 6.2 Number of tracks 6.2.1 4-track format In the4-track format only tracks0,1,2
30、 and3 are usable. Tracks are recorded sequentially from track0 (seealso10.1). 6.2.2 9-track format In the9-track format all nine tracks are usable. Tracks are recorded sequentially from track0 (seealso10.2). 6.3 Track width The recorded track width shall be for a4-track format:0,914 0,025mm(0.036 0.
31、001in); for a9-track format:0,343 0,013mm(0.0135 0.0005in). 7 Recording 7.1 Method of recording The recording method shall be the “Non Return To Zero Mark” (NRZ1) method where a ONE is represented by a change of direction of longitudinal magnetization. 7.2 Physical recording densities The maximum no
32、minal physical recording density shall be394ftpmm. The nominal bit cell length shall be2,544m. Two other densities occur with the recording method described in this part of ISO8462, namely: 197ftpmm(5000ftpi) 131ftpmm(3333ftpi) 7.3 Average bit cell length variations 7.3.1 Average bit cell length The
33、 average bit cell length is the sum of the distances between the flux transitions in n bit cells divided by (n 1). The tests below may be made in any continuously recorded pattern, provided that the first and the last bit cell each contain a flux transition. 7.3.2 Long-term average bit cell length T
34、he long-term average bit cell length is the average bit cell length taken over at least900000 bit cells. The long-term average bit cell length shall be within4% of the nominal bit cell length. 7.3.3 Short-term average bit cell length The short-term average bit cell length is the average bit cell len
35、gth taken over126 to130 bit cells. The short-term average bit cell length shall be within7% of the long-term average bit cell length. 7.4 Flux transition spacing In the following tests the results are expressed as the ratio of measurements; the effects of variations in long-term average bit-cell len
36、gth and short-term average bit-cell length are thereby eliminated. 7.4.1 Instantaneous flux transition spacing The instantaneous spacing between flux transitions is influenced by the reading and writing processes, the pattern recorded (pulse-crowding effect) and other factors. Instantaneous spacings
37、 between flux transitions shall satisfy the following conditions (seeFigure 2).BS7080-2:1989 BSI 01-2000 3 In a sequence of flux transitions defined by the bit pattern11100111, for example as occurs in the Block Marker (see13.1.2), the centre flux transition of each group of three ONEs is called a R
38、eference Flux Transition. The spacing between any pair of contiguous ONE flux transitions shall not deviate by more than35% from the bit cell length d 1averaged over the five bit cells between reference flux transitions. 7.4.2 Rate of change of average flux transition spacing In a sequence of flux t
39、ransitions defined by the data pattern10100101 the rate of change of the average flux transition spacing, averaged over four flux transition spacings, shall not exceed0,0026 per flux transition spacing, i.e.in the pattern shown in Figure 3. d = 1,773mm(0.070in) nominal d 0 = 4,369 0,107mm(0.1720 0.0
40、042in) d 1 = 6,807 0,107mm(0.2680 0.0042in) d 2 = 3,150 0,107mm(0.1240 0.0042in) d 3 = 5,588 0,107mm(0.2200 0.0042in) d 4 = 4,978 0,107mm(0.1960 0.0042in) d 5 = 7,417 0,107mm(0.2920 0.0042in) d 6 = 3,759 0,107mm(0.1480 0.0042in) d 7 = 6,198 0,107mm(0.2440 0.0042in) d 8 = 2,540 0,107mm(0.1000 0.0042i
41、n) Figure 1 BS7080-2:1989 4 BSI 01-2000 7.5 Signal amplitude of a recorded cartridge for data interchange For the4-track format the width of the track read shall be0,508 0,025mm(0.020 0.001in) and shall be within the recorded track. For the9-track format the track read shall extend over the whole wi
42、dth of the recorded track. When performing the tests, the output or resultant signal shall be measured on the same pass for both the Standard Amplitude Reference Tape Cartridge and the tape under test (i.e.the read-whilst-write pass or the first forward-read pass) on the same equipment. The signal a
43、mplitude shall be measured at a point in the read chain at which the signal is proportional to the rate of change of the flux induced in the head. After writing, the cartridge shall meet the following requirements. 7.5.1 Average signal amplitude at nominal maximum density At the nominal maximum dens
44、ity of394ftpmm(10000ftpi) the average peak-to-peak signal amplitude of any track shall be within+50% and35% of SRA 394(seeISO8462-1). This averaging shall be made over the central100 flux transitions of any120 contiguous flux transitions in a block and over at least100 blocks. 7.5.2 Minimum signal a
45、mplitude When interchanged, a tape shall not contain in the valid information area any flux transition the base-to-peak signal amplitude of which is less than25% of half of SRA 394(seeISO8462-1). 1,35 d 1 W d 2 W 0,65 d 1 1,35 d 1 W d 3 W 0,65 d 1 1,35 d 1 W d 4 W 0,65 d 1 1,35 d 1 W d 5 W 0,65 d 1
46、d 1= 0,20 d 6 Figure 2 Figure 3 BS7080-2:1989 BSI 01-2000 5 7.5.3 Maximum signal amplitude The peak-to-peak signal amplitude at131ftpmm(3333ftpi) shall be less than three times SRA 394 . 8 Erasure The tape shall be AC erased. After erasure any remaining signal amplitudes at, or below, twice the freq
47、uency corresponding to the maximum physical recording density shall be less than3% of SRA 394 . 9 Recording offset angle On any track the angle that a flux transition across the track makes with a line perpendicular to Reference Plane B shall not exceed9 of arc. 10 Use of tracks 10.1 4-track format
48、10.1.1 Each track shall be a data track and shall be written serially. 10.1.2 Tracks shall be recorded in the numerical order of their track numbers, starting with track0. 10.1.3 Tracks0 and2 shall be recorded in the direction from the BOT marker to the EOT marker. Tracks1 and3 shall be recorded in
49、the direction from the EOT marker to the BOT marker. 10.1.4 On track0 a Reference Burst recorded at the maximum nominal recording density of394ftpmm(10000ftpi) shall be written between the BOT marker and data recorded on track0. This Reference Burst shall commence not more than381mm(15in) from the BOT marker and extend for a minimum length of76,2mm(3in) and a maximum length of101,6mm(4in) beyond the LP marker. 10.1.5 On tracks0 and2 data shall commence not less than76,2mm(3in) and not more than101,6mm(4in) after the LP
