ISO/IEC 9661:1994

lSO/IEC
INTERNATIONAL
STANDARD
Second edition
1994-l 2-l 5
Information technology - Data
interchange on 12,7 mm wide magnetic
j
18 tracks, 1491 data
tape cartridges -
bytes per millimetre
- khange de don&es sur cartouches de
Technologies de I’informa tion
bande magnktique de 12,7 mm de large - 18 pistes, 1491 caractG.res
par millimi! tre
Reference number
lSO/IEC 9661 :I 994(E)
Page
Contents
Section 1 - General
Conformance
Normative references
4 Definitions
4.1 Average signal amplitude
4.2 Back surface
Beginning of Tape (BOT)
4.3
4.4 Byte
4.5 Cartridge
4.6 Cyclic Redundancy Check character
4.7 Data density
Error Correcting Code
4.8
4.9 Flux transition position
4.10 Flux transition spacing
4.11 Magnetic tape
Master Standard Reference Tape
4.12
4.13 Physical recording density
4.14 Postamble
4.15 Preamble
Reference field
4.16
4.17 Secondary Standard Reference Tape
4.18 Standard reference amplitude
4.19 Standard reference current
Test recording current
4.20
4.21 Track
4.22 Typical field
5 Environment and safety
Cartridge/Tape testing environment
5.1
Cartridge operation environment
5.2
53 Cartridge storage environment
5:4 Safetv requirements
@ ISO/IEC 1994
All rights reserved. No part of this publication may be reproduced or utilized in any form or
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Printed in Switzerland
ISO/IEC 9661t1994 (E)
5.4.1 Safety
5.4.2 Flammability
5.5 Transportation
Section 2 - Tape requirements
6 Characteristics of the tape
Material
6:i Tape length
6.3 Tape width
. Tape discontinuity
65 Total thickness of tape
6:6 Base material thickness
67 Longitudinal curvature
6:8 Out-of-plane distortions
Cupping
Dynamic frictional characteristics
6’10 .
Frictional drag between the recording surface and the tape back surface
6.10.1
6.10.2 Frictional drag between the tape recording surface and ferrite after environmental cycling
Coating adhesion
6.11
Flexural rigidity
6.12
6.13 Electrical resistance of coated surfaces
6.14 Tape durability
6.15 Inhibitor tape
Tape abrasivity
6.16
Pre-recording condition
6.17
6.18 Magnetic recording characteristics
6.18.1 Typical field
Signal amplitude
6.18.2
Resolution
6.18.3
6.18.4 Overwrite
6.18.5 Narrow-Band Signal-to-Noise Ratio (NB-SNR)
Tape quality
6.19
Missing pulses
6.19.1
6.19.2 Missing pulse zones
6.19.3 Coincident missing pulse zones
3 - Cartridge requirements
Section
Dimensional and mechanical characteristics of the cartridge
7.1 Overall dimensions (figures 4 to 6)
5)
72 Write-inhibit mechanism (figures 4 and
7:3 Label area of the rear side (figures 5 and 6)
Label area of the top side (figure 5)
7.4
7.5 Case opening (figures 4,5,7 and 9)
7.6 Locating notches (figures 7,8 and 10)
Locating areas (figure 7)
7.7
Inside configuration of the case around the case opening (figures 7 and 11)
7.8
7.9 Other external dimensions of the case (figure 8)
7.10 Central window (figure 7)
7.11 Stacking ribs
7.12 Flexibility of the case
7.12.1 Requirements
. . .
-
7.12.2 Procedure
7.13 Tape reel (figures 12 and 13)
Locking mechanism (figure 13)
7.13.1
Axis of rotation of the reel
7.13.2
7.133 Metallic insert
7.13.4 Toothed rim
7.13.5 Hub of the reel
Relative positions
7.13.6
7.13.7 Characteristics of the toothed rim (figure 12)
7.14 Leader block (figure 15)
7.15 Attachment of the tape to the leader block (figure 16)
Latching mechanism (figure 17)
7.16
7.17 Tape wind
7.18 Wind tension
7.19 Circumference of the tape reel
Moment of inertia
7.20
Section 4 - Recording requirements
8 Method of recording
8.1 Physical recording density
8.2 Bit cell length
Average bit cell length
83 .
84 l Long-term average bit cell length
85 0 Short-term average bit cell length
86 0 Rate of change
Bit shift
87 l
88 . Total character skew
89 Read signal amplitude
8’10 . Coincident missing pulses
9 Track format
9.1 Number of tracks
9.2 Reference edge
9.3 Track positions
9.4 Track width
Azimuth
9.5
10 Data format
10.1 Types of bytes
10.1.1 Data bytes
10.1.2 Pad bytes
10.2 Frame
10.3 Data Block
Prefix
10.3.1
?
10.3.2 Data Frames
10.3.3 Residual Frame 1
Residual Frame 2
10.3.4
10.3.5 Summary of requirements for Residual Frames
10.3.6 Suffix
10.4
Error Correcting Code (ECC)
10.4.1 Diagonal Redundancy Check (DRC)
iv
10.4.2 Vertical Redundancy Check (VRC)
10.4.3 ECC Format
10.4.4 Summary of ECC
10.5 Recording of &bit bytes on the tape
10.6 Recorded Data Block
10.6.1 Preamble
10.6.2 Beginning of Data Mark (BDM)
10.6.3 Resync Control Frame
10.6.4 End of Data Mark (EDM)
Postamble
10.6.5
10.7 Data density
11 Tape format
11.1 Density Identification Burst
11.2 ID Separator Burst
113 Interblock Gaps
11.4 Erase Gaps
11.4.1 Normal Erase Gaps
11.4.2 Elongated Erase Gaps
Tape Marks
11.5
11.6 Relationship between Interblock Gaps, Erase Gaps and Tape Marks
11.6.1 Interblock Gap followed by a Tape Mark
11.6.2 Tape Mark followed by an Interblock Gap
11.6.3 Interblock Gap followed by an Erase Gap
11.6.4 Erase Gap followed by an Interblock Gap
11.6.5 Summary of the relationship between Interblock Gaps, Erase Gaps and Tape Marks
11.7 First and last recording on the tape
11.8 Summary of the tape format
11.8.1 Characteristics of recording other than recorded Data Blocks
11.8.2 Arrangement of recording on the tape
Annexes
A - Recommendations for transportation
B - Inhibitor tape
C - Tape abrasivity measurement procedure
D - Recommendations on tape durability
E - Pre-recording condition
F - Representation of &bit bytes by g-bit patterns
G - Measurement of bit shift
H - Dimensions of the cartridge ,

ISO/IEC 9661t1994 (E) -
Foreword
IS0 (the International Organization for Standardization) and IEC (the Inter-
national 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 9661 was prepared by Joint Technical Committee
ISO/IEC JTC 1, Information technology, Subcommittee SC 11, Flexible magnetic
media for digital data interchange.
This second edition cancels and replaces the first edition (IS0 9661: 1988).
Annexes C, E, F and G form an integral part of this International Standard.
Annexes A, B, D and H are for information only.
vi
INTERNATIONAL STANDARD
Information technology - Data interchange on 12,7 mm wide magnetic tape
cartridges - 18 tracks, 1491 data bytes per millimetre
Section 1 - General
1 Scope
This International Standard specifies the physical and magnetic characteristics of a 12,7 mm wide, H-track magnetic tape
cartridge to enable interchangeability of such cartridges. It also specifies the quality of the recorded signals, the format and
recording method thus allowing, together with IS0 1001 for magnetic tape labelling, full data interchange by means of such
magnetic tape cartridges.
2 Conformance
A magnetic tape cartridge shall be in conformance with this International Standard if it meets all mandatory requirements
specified herein. The tape requirements shall be satisfied throughout the extent of the tape.
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 listed below. Members of IEC and IS0 maintain registers of currently valid International Standards.
ISO/IEC 646: 199 1, Information technology - IS0 7-bit coded character set for information interchange.
Part 13: Wrought stainless steels.
IS0 683-13: 1986, Heat-treatable steels, alloy steels and free-cutting steels -
IS0 1001: 1986, Information processing - File structure and labelling of magnetic tapes for information interchange.
IS0 1302: 1992, Technical drawings - Method of indicating su@ace texture.
ISO/IEC 2022: 1994, Information technology - Character code structure and extension techniques.
ISO/IEC 4873: 199 1, Information technology - IS0 &bit code for information interchange - Structure and rules for
implementation.
4 Definitions
For the purposes of this International Standard, the following definitions apply.
4.1 Average signal amplitude: The average peak-to-peak value of the signal output of the read head measured over a
minimum of 25,4 mm of tape exclusive of missing pulses.
4.2 Back surface: The surface of the tape opposite the magnetic coating used to record data.
4.3 Beginning of Tape (BOT): The point along the length of the magnetic tape indicated by the start of the Density
Identification Burst.
Byte: An ordered set of eight bits acted upon as a unit and recorded as a 9-bit pattern.
4.4
4.5 Cartridge: A container holding a supply reel of magnetic tape with an attached leader block.
4.6 Cyclic Redundancy Check character: A character represented by two bytes, placed at the end of a Data Block and
used for error detection.
Data density: The number of &bit bytes stored per unit length of tape, expressed in bytes per millimetre.
4.7
4.8 Error Correcting Code: A mathematical procedure yielding bits used for the detection and correction of errors.
ISODEC 9661:1994 (E)
Flux transition position: That point which exhibits maximum free-space flux density normal to the tape surface.
4.9
4.10 Flux transition spacing: The distance along a track between successive flux transitions.
and retain the magnetic signals intended for input, output
4.11 Magnetic tape: A tape which will accept
purposes on computers and associated equipment.
amplitude, resolution
4.12 Master Standard Reference Tape: A tape selected as the for reference field, signal
and overwrite.
Note - A Master Standard Reference Tape has been established at the National Institute for Standards and Technology (NIST) for this International Standard.
4.13 Physical recording density: The number of recorded flux transitions per unit length of track, expressed in flux
transitions per millimetre (ftpmm).
4.14 Postamble: A repeated 9-bit pattern at the end of a recorded Data Block providing electronic synchronization when
reading in the reverse direction.
beginning recorded Data Block providing electronic synchronization
4.15 Preamble: A repeated 9-bit pattern at the of a
when reading in the forward direction
4.16 Reference field: The typical field of the Master Standard Reference Tape.
4.17 Secondary Standard Reference Tape: A tape the performance of which is in relation to that of the
Master
Standard Reference Tape.
Note - Secondary Standard Reference Tapes have been developed at the National Institute for Standards and Technology (NIST) and are available fkom the
NIST Office of Standard Reference Materials, Room 205, Building 202, National Institute of Standards and Technology, Gaithersburg, MA 20899, USA,
under reference number SRM 3202, until January 2004.
It is intended that these be used for calibrating tertiary reference tapes for use in routine calibration.
4.18 Standard reference amplitude: The average signal amplitude from the Master Standard Reference Tape when it is
recorded with the test recording current on the NIST measurement system at 972 ftpmm.
Traceability to the standard reference amplitude is provided by the calibration factors supplied with each Secondary Standard
Reference Tape.
4.19 Standard reference current: The current that produces the reference field.
4.20 Test recording current: The current that is 1,5 times the standard reference current.
4.21 Track: A longitudinal area on the tape along which a series of magnetic signals may be recorded.
4.22 Typical field: In the plot of the average signal amplitude against the recording field at the physical recording density
of 972 fipmm, the minimum field that causes an average signal amplitude equal to 85 % of the maximum average signal
amplitude.
5 Environment and safety
room and not to
Unless otherwise stated, the conditions specified below refer to the ambient conditions in the test or computer
those within the tape equipment.
51 0 Cartridge/Tape testing environment
Unless otherwise stated, tests and measurements made on the tape cartridge to check requirements of this International
Standard shall be carried out under the following conditions:
temperature: 23 “C k 2 “C
relative humidity: 40 % to 60 %
conditioning period
before testing: 24 hours.
l Cartridge operation environment
Cartridges used for data interchange shall be capable of operating under the following conditions:
temperature: 16 “C to 32 “C
relative humidity: 20 % to 80 %
wet bulb temperature: 25 “C max.
The average temperature of the air immediately surrounding the tape shall not exceed 40
...