ISO-1861-1975.pdf
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1、INTERNATIONAL STANDARD INTERNATIONAL ORGANIZATION FOR STANDARDIZATION .MEX; Descriptors : data processing, magnetic tapes, information interchange, specifications. cc Price based on 7 pages Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA
2、Technical Standards 1/9972545001 Not for Resale, 04/25/2007 02:26:10 MDTNo reproduction or networking permitted without license from IHS -,-,- FOREWORD IS0 (the International Organization for Standardization) is a worldwide federation of national standards institutes (IS0 Member Bodies). The work of
3、 developing International Standards is carried out through IS0 Technical Committees. Every Member Body interested in a subject for which a Technical Committee has been set up has the right to be represented on that Committee. International organizations, governmental and nongovernmental, in liaison
4、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. International Standard IS0 1861 was drawn up by Technical Committee ISO/TC 9
5、7, Computers and information processing, and circulated to the Member Bodies in October 1973. It has been approved by the Member Bodies of the following countries : Belgium Italy Brazil Mexico Czechoslovakia New Zealand Egypt, Arab Rep. of Poland France Portugal Germany Romania Hungary South Africa,
6、 Rep. of Ireland Spain Sweden Switzerland Thailand Turkey United Kingdom U.S.S.R. Yugoslavia This International Standard cancels and replaces IS0 Recommendation R 1861-1971, of which it constitutes a technical revision. 0 International Or9mization for Standardization, 1975 0 Printed in Switzerland C
7、opyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/25/2007 02:26:10 MDTNo reproduction or networking permitted without license from IHS -,-,- INTERNATIONAL STANDARD IS0 1861-1975 (E) Informa
8、tion processing - 7-track, 12,7 mm (0.5 in) wide magnetic tape for information interchange recorded at 8 rpmm (200 rpi) 1 SCOPE AND FIELD OF APPLICATION This International Standard specifies a 7-track, 8 rows per millimetre (rpmm) 200 rows per inch (rpi) 12.7 mm (0.5 in) wide magnetic tape for inter
9、changeability of tape between information processing systems which utilize 6- and 7-bit coded character sets, the latter being as specified in IS0 646. It refers solely to magnetic tape for digital recording, on which the direction of magnetization is nominally longitudinal as opposed to nominally t
10、ransverse. NOTES 1 Certain other aspects of coding requirements, such as significance of binary digits, sequence of characters, filling of unused positions and magnetic labelling for use on magnetic tape, are the subject of ISO/R 961 and ISO/R 1001. 2 Details of unrecorded tape and reels are specifi
11、ed in the complementary publication, IS0 1864. 2 REFERENCES ISO/R 961, Implementation of the 6 and 7-bit coded character sets on 7-track, 12,7 mm (l/2 in) magnetic tape. ISO/R 1001, Magnetic tape labelling and file structure for information interchange. IS0 1864, information processing - Unrecorded
12、12,7 mm (0.5 in) magnetic tape for information interchange - 8 and 32 rpmm (200 and 800 rpi), NRZI, and 63 rpmm / 1 600 rpi), phase-encoded. ) 3 DEFINITIONS NOTE - The material contained in clauses 3 and 4 of this International Standard is duplicated from IS0 1864 for unrecorded magnetic tape. The l
13、atter document shall be considered to be correct, that is, the primary document, so far as any differences between the comparable clauses of the two documents are concerned. For the purpose of this International, Standard, the following definitions apply : 3.1 magnetic tape : Tape which will accept
14、and retain magnetic signals intended for input, output and storage purposes on computers and associated equipment. 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 p
15、erformance is known and stated in relation to that of a reference tape. 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 U.S. National Bureau of Standards (NBS) base
16、d on reference tapes and heeds. Secondary signal amplitude reference tapes are available from NBS under the part number SRM 3200. 3.5 reference field : For any specified packing density, the minimum field applied to the signal amplitude reference tape which causes an output signal equal to 95 % of t
17、he maximum output. 3.6 standard reference amplitude : The average peak-to-peak signal amplitude derived from the signal amplitude reference tape (SRM 3200) on the NBS measurement system, or equivalent, at the recording current equal to 2.1 X the current needed to produce the reference field. 3.7 ref
18、erence edge : The edge further from an observer, or nearer the top of the page, when a tape is lying flat with the magnetic surface uppermost and the direction of movement for recording from left to right. (See figures 1 and 2.) 3.8 in contact : An operating condition in which the magnetic surface o
19、f a tape is in contact with a magnetic head. 3.9 track : A longitudinal area on the tape along which a series of magnetic signals may be recorded. 3.10 packing density : The number of bits of recorded information per unit length of track. 3.11 inter-block gap : A DC-erased section of tape separ- ati
20、ng blocks of information. 1) At present at the stage of draft. (Revision of ISO/R 1864.1 1 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/25/2007 02:26:10 MDTNo reproduction or networki
21、ng permitted without license from IHS -,-,- IS0 1861-1975 (E) 4 REFLECTIVE MARKERS (See note introducing clause 3, and figure 3) Each reel of tape shall be furnished with two photo-reflective markers, each consisting of, or equivalent to, a transparent plastic base with a metallic (for example vapor
22、ized aluminium) coating sandwiched between the base and a thin layer of low cold flow thermal setting adhesive. Reflective markers shall be placed on the side of the tape which does not carry the magnetic surface, and they shall be on opposite edges of the tape with the beginning-of-tape reflective
23、marker (BOT) on the reference edge. The width of the markers shall be 4,8 + 0.5 mm (0.19 + 0.02 in). The length of the markers shall be 28 f 5 mm (1 .l It 0.2 in). The thickness of the markers, measured after their appli- cation to the tape, shall be not greater than 0,020 mm (0.000 8 in). The begin
24、ning-of-tape reflective marker (BOT) shall be placed 4,9 + 0.6 m (16 + 2 ft) from the beginning of the tape and the end-of-tape marker (EOT) shall be placed 7,6 b ” m (25 + i ft) from the end of the tape. The distance from the outer edge of a marker to the adjacent edge of the tape shall be 0.8 mm (
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