ISO/IEC 15731:1998

INTERNATIONAL
ISOAEC
STANDARD 15731
First edition
1998-05 15
Information technology - 12,65 mm wide
magnetic tape cassette for information
interchange - Helical scan recording -
DTF-1 format
Technologies de Yin formation - Cassette de bande magrktique de
12,65 mm de large pour khange d ’information - Enregistrement par
balayage en spirale - Format DTF- I
Reference number
ISO/I EC 15731: 1998(E)
Contents
Section 1 - General
1 Scope
2 Conformance
2.1 Magnetic tape cassette
2.2 Generating system
2.3 Receiving system
3 Normative references
4 Definitions
4.1 Absolute block number
4.2 a.c. erase
4.3 algorithm
4.4 Append file
4.5 Append volume
4.6 Average Signal Amplitude (ASA)
4.7 azimuth
4.8 back surface
4.9 bit cell
4.10 block
4.11 Block Management Table (BMT)
4.12 byte
4.13 cassette
4.14 compressed data
4.15 Control Track
4.16 flux transition position
4.17 flux transition spacing
4.18 Logical track set ID
4.19 Logical volume
4.20 magnetic tape
4.21 Master Standard Reference Tape (MSRT)
4.22 physical recording density
0 ISO/IEC 1998
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic
or mechanical, including photocopying and microfilm, without permission in writing from the publisher.
ISO/IEC Copyright Office l Case Postale 56 l CH-1211 Geneve 20 l Switzerland
Printed in Switzerland
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4.23 Reference Field (RF)
4.24 Secondary Standard Reference Tape (SSRT)
4.25 Standard Reference Amplitude (SRA)
4.26 Standard Reference Current (Ir)
4.27 Tape Reference Edge
4.28 Test Recording Current (TRC)
4.29 track
4.30 track angle
Track Set
4.31
4.32 Typical Field (TF)
4.33 Unique Identifier (UID)
4.34 word
5 Conventions and notations
5.1 Representation of numbers
5.2 Names
6A cronyms
7 Environment and safety
7.1 Testing environment
7.2 Operating environment
7.3 Storage environment
7.4 Transportation
Safety
7.5
7.6 Flammability
Section 2 - Requirements for the case
8 Dimensional and mechanical characteristics of the case
8.1 General
8.2 Type S cassette
8.2.1 Overall dimensions
8.2.2 Holding areas
8.2.3 Window
8.2.4 Label areas
8.2.5 Datum areas and datum holes
8.2.6 Support areas
8.2.7 Guiding grooves
8.2.8 Recognition holes
8.2.9 Write-inhibit plug
8.2.10 Pre-positioning surface
8.2.11 Cassette lid
8.2.12 Cassette reel lock
8.2.13 Reel access holes
8.2.14 Reels
8.2.15 Position of the tape in the case
8.2.16 Tape path zone
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8.2.17 Tape access cavity
8.3 Type L cassette
8.3.1 Overall dimensions
8.3.2 Holding areas
8.3.3 Window
8.3.4 Label areas
8.3.5 Datum areas and datum holes
8.3.6 Support areas
8.3.7 Guiding grooves
8.3.8 Recognition holes
8.3.9 Write-inhibit plug
8.3.10 Pre-positioning surface
8.3.11 Cassette lid
8.3.12 Cassette reel lock
8.3.13 Reel access holes
8.3.14 Reels
8.3.15 Position of the tape in the case
8.3.16 Tape path zone
8.3.17 Tape access cavity
8.3.18 Cavity for compatibility with Type S cassette
Section 3 - Requirements for the unrecorded tape
9 Mechanical, physical and dimensional characteristics of the tape
9.1 Materials
9.2 Tape length
9.3 Tape widths
9.4 Width and position of splicing tape
9.5 Discontinuity
9.6 Tape thickness
9.7 Longitudinal curvature
9.8 Out-of-plane distortions
9.9 Coating adhesion
9.10 Layer-to-layer adhesion
9.11 Tensile strength
9.11.1 Breaking strength
9.11.2 Yield strength
9.11.3 Strength of Splice
9.12 Residual elongation
9.13 Electrical resistance of the coated surfaces
9.14 Tape wind
10 Magnetic recording characteristics
10.1 Typical Field TFl
10.2 Average Signal Amplitude(ASA)
10.3 Resolution
10.4 Signal-to-noise ratio (S/N)
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10.5 Ease of erasure
10.6 Tape quality
10.6.1 Missing pulses
10.6.2 Missing pulse zone
10.7 Inhibitor tape
Section 4 - Requirements for an interchanged tape
11 Format for helical tracks
11.1 General description of the write data path
11.2 Formation of a Logical Track Set
11.2.1 Types of information track sets
11.2.2 Generation of a Logical Track Set
11.2.3 Subcode data field
11.2.4 BMT
11.2.5 Data and information field definitions
11.3 Track Set information
11.3.1 Loading the Product Code Arrays
11.4 Product code array processing
11.4.1 Error correction method
11.4.2 Error correction coding for Cl Parity
11.5 Track assignments
11.5.1 Sectors
11.5.2 Sync Blocks
11.5.3 Track interleave
11.5.4 Track Sync Blocks
11.5.5 Byte interleave across Sync Blocks
11.5.6 Randomization
11.6 Formation of the contents of a helical track
11.6.1 Sector details (figure 50)
11.7 Channel bit coding (annex B)
11.7.1 General
11.7.2 Interleaved-NRZ 1
12 Track geometry
12.1 General
12.2 Helically recorded tracks
12.2.1 Location of the tracks
12.2.2 Track width
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12.2.3 Track angle
12.2.4 Track pitch
12.2.5 Location of elements in the helical track
12.2.6 Location of the Data Area Reference Point
12.2.7 Straightness of tracks
12.2.8 Azimuth angles
12.2.9 Tracking Pilot Signal (TPS)
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12.2.10 Amplitude of servo signals
12.3 Longitudinal tracks geometry
12.3.1 Control Track
12.3.2 Time Code Track signals recording position
13 Method of recording helical tracks
13.1 Physical recording density
13.2 Record current optimization
13.3 Efficiency of erasure
14 Method of recording longitudinal tracks
14.1 Overview
14.2 Control Track
14.2.1 Signal
14.2.2 Polarity of magnetisation (figure 53)
14.2.3 Alignment
14.2.4 Read signal amplitude
14.2.5 Quality of the Control Track
14.3 Time Code Track
14.3.1 Method of recording the Time Code Track
14.3.2 Physical recording density
14.3.3 Bit shift
14.3.4 Read signal amplitude
14.3.5 Quality of the Time Code Track
14.4 Format for the Time Code Track
14.4.1 Count bits
14.4.2 Phase bit
14.4.3 Synchronizing pattern
14.4.4 Supplemental Data
14.4.5 Extent of Time Code
Section 5 - Requirements for recorded information
15 Recorded information
15.1 Recording area (figure 54)
15.2 Magnetic tape layout (figure 55)
15.2.1 Valid data areas
152.2 Invalid data areas
15.3 Physical TSID
15.3.1 Structure surrounding the VSIT area
15.3.2 Structure of the DIT area
15.3.3 Structure of the User Data Area
Section 6 - Write operations
16 Write retry sequence
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17 Append file operation
17.1 Append volume
17.2 Append write
17.3 Overwrite
17.4 File extension
Annexes
A - Measurement of Signal-to-Noise Ratio
B - Representation S/9 coding patterns
C - Recommendations for Transportation
D - Inhibitor Tape
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Foreword
IS0 (the International Organization for Standardization) and IEC (the International Electrotechnical Commission) form the
specialized system for worldwide standardization. National bodies that are members of IS0 or IEC participate in the
development of International Standards through technical committees established by the respective organization to deal with
particular fields of technical activity. IS0 and IEC technical committees collaborate in fields of mutual interest. Other
international organizations, governmental and non-governmental, in liaison with IS0 and IEC, also take part in the work.
In the field of information technology, IS0 and IEC have established a joint technical committee, ISO/IEC JTC 1. Draft
International Standards adopted by the joint technical committee are circulated to national bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the national bodies casting a vote.
International Standard ISO/IEC 1573 1 was prepared by ECMA (as Standard ECMA-248) and was adopted, under a special
“fast- track procedure ”, by Joint Technical Committee ISO/IEC JTC 1, Information technology, in parallel with its approval by
national bodies of IS0 and IEC.
Annexes A, and B form an integral part of this International Standard. Annexes C and D are for information only.
IS0 and IEC draw attention to the fact that it is claimed that compliance with this International Standard may involve the use
of patents concerning the Master Standard Reference Tape and Secondary Standard Reference Tape given in clause 4.
IS0 and IEC take no position concerning the evidence, validity and scope of this patent right.
The holder of this patent right has assured IS0 and IEC that he is willing to negotiate licences under reasonable and non-
discriminatory terms and conditions with applicants throughout the world. In this respect, the statement of the holder of this
patent right is registered with IS0 and IEC. Information may be obtained from:
Sony Corporation
Contracts and Licensing Division
Tokyo international
P.O. Box 5100 Tokyo
100-3 1 Japan
Attention is drawn to the possibility that some of the elements of this International Standard may be the subject of patent rights
other than those identified above. IS0 and IEC shall not be held responsible for identifying any or all such patent rights.
. . .
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INTERNATIONAL STANDARD 0 ISO/IEC ISO/IEC 15731:1998 (E)
Information technology - 12,65 mm wide magnetic tape cassette for information
interchange - Helical scan recording - DTF-1 format
Section 1 - General
1 Scope
This International Standard specifies the physical and magnetic characteristics of magnetic tape cassettes, using magnetic tape
12,65 mm wide so as to provide physical interchange of such cassettes between drives. It also specifies the quality of the
recorded signals, the recording method and the recorded format, called Digital Tape Format-l (DTF-l), thereby allowing data
interchange between drives by means of such cassettes. The format supports variable length Logical Records, high speed
search, and the use of a registered algorithm for data compression.
This International Standard specifies two sizes of cassette. For the purposes of this International Standard the larger cassette is
referred to as Type L, and the smaller as Type S.
Together with a standard for volume and file structure, e.g. IS0 1001, this International Standard provides for full data
interchange between data processing systems.
2 Conformance
Magnetic tape cassette
21 .
A claim of conformance with this International Standard shall specify the Type of cassette. It shall be in conformance with this
International Standard if
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the case meets all the requirements of clause 4 and clauses 6 to 10 for that Type
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the recording on the tape meets the requirements of clauses 11 to 17
22 . Generating system
A claim of conformance with this International Standard shall specify which Type(s) of cassette is (are) supported. A system
generating a magnetic tape cassette for interchange shall be in conformance with this International Standard if all the
recordings that it makes, meet the mandatory requirements of this International Standard. A claim of conformance with this
International Standard shall state whether or not one, or more, registered algorithm(s) is (are) implemented and, if so, the
registered number(s) of (all) the implemented algorithm(s).
23 . Receiving system
A claim of conformance with this International Standard shall specify which Type(s) of cassette is (are) supported. A system
receiving a magnetic tape cassette for interchange shall be in conformance with this International Standard if it is able to
handle any recording made on the tape according to this International Standard, and a claim of conformance shall state
whether or not one, or more, registered algorithm(s) is (are) implemented and, if so, the registered number(s) of (all) the
implemented algorithm(s).
3 Normative references
The following standards contain provisions which, through reference in this text, constitute provisions of this International
Standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to
agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent
editions of the standards indicated below. Members of IEC and IS0 maintain registers of currently valid International
Standards.
Plastics - Determination of tensile properties.
IS0 527 (all parts),
File structure and labelling of magnetic tapes for information
IS0 1001:1986, Information processing -
interchange.
ISO/IEC 11576: 1994, Information technology - Procedure for the registration of algorithms for the lossless
compression of data.
IEC 950:1991, Safety of information technology equipment.
JIS-B-7502, Characteristics of plastic goods.
SMPTE timecode: (C98.12 : time and control code for video and audio tape for 525/60 television system).
OISOAEC
ISOLIEC 15731:1998 (E)
Definitions
For the purposes of this International Standard, the following definitions apply.
to each block, indicating that the block is the Nth block from
41 . Absolute block number: A number N allocated
the beginning of the Logical volume containing it.
42 . a.c. erase: A process of erasure utilizing alternating magnetic fields of decaying intensity,
43 . algorithm: A set of rules for transforming the logical representation of data.
44 . Append file: A new file added from the End of Data (EOD) of a Logical volume.
45 . Append volume: A Logical volume added after the last Logical volume recorded on the cassette.
output of a read head
46 . Average Signal Amplitude (ASA): The average peak-to-peak value of the signal
measured over a minimum of 1,40 mm of tr
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