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
by any means, electronic or mechanical, including photocopying and microfilm, without per-
mission in writing from the publisher
ISO/lEC Copyright Office * Case Postale 56 l CH-1211 Genbve 20 * Switzerland
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 405 “C.
Note - Localized tape temperatures in excess of 49 “C may cause tape damage.
storage and/or transportation to conditions outside the
Conditioning before operating: If a cartridge has been exposed during
above values, it shall be conditioned for a period of at least 24 hours.
53 l Cartridge storage environment
Cartridges used for data interchange shall be stored under the following conditions.
temperature: 5 “C to 32 “C
relative humidity: 5 % to 80 %
wet bulb temperature: 26 “C max.
54 0 Safety requirements
5.4.1 Safety
The cartridge and its components shall not constitute any safety or health hazard when used in its intended manner or in any
foreseeable misuse in an information processing system.
5.4.2 Flammability
The cartridge and its components shall be made from materials which, if ignited from a match flame, do not continue to bum
in a still carbon dioxide atmosphere.
55 l Transportation
This International Standard does not specify parameters for the environment in which cartridges should be transported. Annex
A gives some recommendations for transportation.
Section 2 - Tape requirements
6 Characteristics of the tape
61 a Material
The tape shall consist of a base material (oriented polyethylene terephthalate film or its equivalent) coated on one side with a
strong, yet flexible layer of ferromagnetic material dispersed in a suitable binder. The back surface of the tape may also be
coated with a ferromagnetic or non-ferromagnetic material.
62 0 Tape length
The length of the tape shall not be less than 165 m.
Tape width
63 l
The width of the tape shall be 12,650 mm & 0,025 mm. The width shall be measured across the tape from edge-to-edge when
the tape is under a tension of less than 0,28 N.
64 l Tape discontinuity
There shall be no discontinuities in the tape such as those produced by tape splicing or perforations.
65 l Total thickness of tape
The total thickness of the tape at any point shall be between 0,0259 mm and 0,0337 mm.
66 a Base material thickness
The thickness of the base material shall be 0,0234 mm nominal.
67 l Longitudinal curvature
The radius of curvature of the edge of the tape shall not be less than 33 m.

Procedure
Allow a length of tape of 1 m to unroll and assume its natural curvature on a flat smooth surface. Measure the deviation from a
1 m chord. The deviation shall not be greater than 3,8 mm. This deviation corresponds to the minimum radius of curvature of
33 m if measured over an arc of circle.
68 0 Out-of-plane distortions
All visual evidence of out-of-plane distortion shall be removed when the tape is subjected to a uniform tension of 0,6 N.
Out-of-plane distortions are local deformations which cause portions of the tape to deviate from the plane of the surface of the
tape. Out-of-plane distortions are most readily observed when the tape is lying on a flat surface under no tension.
69 l Cupping
The departure across the width of tape from a flat surface shall not exceed 0,3 mm.
Procedure
Cut a length of tape of 1,O m k 0,l m . Condition it for a minimum of 3 hours in the test environment by hanging it so that the
coated surface is freely exposed to the test environment. From the centre portion of the conditioned tape cut a test piece of
length 25 mm. Stand the test piece on its end in a cylinder which is at least 25 mm high with an inside diameter of 13,0 mm 2
0,2 mm. With the cylinder standing on an optical comparator measure the cupping by aligning the edges of the sample to the
reticle and determining the distance from the aligned edges to the corresponding surface of the test piece at its centre.
6.10 Dynamic frictional characteristics
In the tests of 6.10.1 and 6.10.2 the specified forces of 1,O N and 150 N, respectively, comprise both the force component of
the dynamic friction and the force of 064 N applied to the test piece of tape.
NOTE - Particular attention should be given to keeping the surfaces clean.
6.10.1 Frictional drag between the recording surface and the tape back surface
The force required to move the recording surface in relation to the back surface shall not be less than 1,0 N.
Procedure
Wrap a test piece of tape around a 254 mm diameter circular mandrel with the back surface of the test piece facing out-
ward.
ii) Place a second test piece of tape, with the recording surface facing in, around the first test piece for a total angle of wrap
of 90”.
iii) Apply a force of 0,64 N to one end of the outer test piece of tape. Secure its other end to a force gauge which is mounted
on a motorized linear slide.
iv) Drive the slide at a speed of 1 mm/s.
6.10.2 Frictional drag between the tape recording surface and ferrite after environmental cycling
The force required to move the tape at a point 1,34 m from the leader block of the cartridge shall not be greater than 1,50 N.
The force required at a point 4,3 m from the junction of the tape with the cartridge hub shall not exceed the first force by more
than a factor of 4.
Procedure
Wind tape on to a spool hub of diameter 50 mm to an outside diameter of 97 mm with a winding tension of 2,2 N sf:
0,2 N.
ii)
Repeat the following two steps five times:
Store for 48 hours at a temperature of 50 “C and a relative humidity of 10 % to 20 %.
a)
Acclimatize in the testing environment for 2 hours and rewind with a tension of 2,2 N k 0,2 N.
b)
iii) Condition the tape for 48 hours at a temperature of 30,5 “C and a relative humidity of 85 %. The tape shall remain in
this environment for steps iv) and v).

iv) Apply a force of 0,64 N to one end of a test piece of tape of not more than 1 m, taken 1,34 m from the leader block. Pass
the test piece over a ferrite rod of diameter 25,4 mm with the recording surface in contact with the rod for a total angle
of wrap of 90”.
The rod shall be made from the ferrite specified in annex C. It shall be polished to a roughness value ra of 0,05 pm
(roughness grade N2, IS0 1302). Pull the other end of the test piece horizontally at 1 mm/s.
Repeat step iv) for a similar test piece taken 4,3 m from the junction of the tape with the cartridge hub.
VI
6.11 Coating adhesion
The force required to peel any part of the coating from the tape base material shall not be less than 1,5 N.
Procedure
Take a test piece of the tape approximately 380 mm long and scribe a line through the recording coating across the
width of the tape 125 mm from one end.
. . .
Using a double-sided pressure sensitive tape, attach the full width of the test piece to a smooth metal piece plate, with
11)
the recording surface facing the plate, as shown in the figure below.
iii) Fold the test piece over 180”, attach the metal plate and the free end of the test piece to the jaws of a universal testing
machine and set the speed of the jaw separation to 254 mm per min.
iv) Note the force at which any part of the coating first separates from the base material. If this is less than 1,5 N, the test
has failed. If the test piece peels away from the double-sided pressure sensitive tape before the force exceeds 1,5 N, an
alternative type of double-sided pressure sensitive tape shall be used.
If the back surface of the tape is coated, repeat i) to iv) for the back coating.
Scribed line
Pressure-sensitive tape
a 125 mm -
Figure 1 - Coating adhesion
6.12 Flexural rigidity
The flexural rigidity of the tape in the longitudinal direction shall be between 0,06 N-mm2 and 0,16 N*mm2.
Procedure
Clamp a 180 mm test piece of tape in a universal testing machine, allowing a 100 mm separation between the machine jaws.
Set the jaw separation speed at 5 mm per minute. Plot force against distance. Calculate the flexural rigidity using the slope of
the curve between 2,2 N and 6,7 N by the formula:
E dF/WT
-
-
dL/L
I =WT3/12
Flexural rigidity = El
where :
6F = change in force in N
= measured thickness in mm
T
= measured width in mm
W
a/L = change in lenght of test piece between the jaws divided by the original length between the jaws.
6.13 Electrical resistance of coated surfaces
The electrical resistance of any square area of the recording surface shall be within the range:
-
1 O5 IR to 5 x lo* Sz for non-backcoated tapes;
-
105 Q to 5 x lo9 Sz for backcoated tapes.
The electrical resistance of any backcoating shall be less than lo6 52.
Procedure
Condition a test piece of tape to the test environment for 24 hours. Position the test piece over two 24-carat gold-plated,
semi-circular electrodes having a radius r - - 25,4 mm and a finish of at least N4, so that the recording surface is in contact with
each electrode. These electrodes shall be placed parallel to the ground and parallel to each other at a distance d = 12,7 mm
between their centres. Apply a force F of 1,62 N to each end of the test piece. Apply a d.c. voltage of 500 V k 10 V across the
electrodes and measure the resulting current flow. From this value, determine the electrical resistance.
Repeat for a total of five positions along the test piece and average the five resistance readings. For back-coated tape repeat the
procedure with the backcoating in contact with the electrodes.
F F
Figure 2 - Position of test piece over two semi-circular electrodes
When mounting the test piece, make sure that no conducting paths exist between the electrodes except that through the coating
under test.
Note - Particular attention should be given to keeping the surfaces clean.
6.14 Tape durability
This International Standard does not specify parameters for assessing tape durability.
However, a recommended procedure is described in annex D.
6.15 Inhibitor tape
This International Standard does not specify parameters for assessing whether or not a tape is an inhibitor tape.
However, annex B gives further information on inhibitor tapes.
6.16 Tape abrasivity
Tape abrasivity is the tendency of the tape to wear the tape transport. The length of the wear pattern on a wear bar shall not
exceed 56 pm when measured as specified in annex C.
6.17 Pre-recording condition
Prior to recording data or to testing, the tape shall have been erased using alternating magnetic fields of decaying levels
(anhysteretic process) to ensure that the remanent magnetic moment of the recording surface does not exceed 20 % of the
maximum remanent magnetic moment. Annex E specifies the method of measurement.
In addition no low density transitions shall be present on the tape.
6.18 Magnetic recording characteristics
The magnetic recording characteristics shall be as defined by the testing requirements given below.
When performing these tests, the output or resultant signal shall be measured on the same relative pass for both a tape
calibrated to the Master Standard Reference Tape and the tape under test (read-while-write or first forward-read-pass) on the
same equipment.
The following conditions shall apply to the testing of all magnetic recording characteristics, unless otherwise stated:
-
tape condition : pre-recording condition
tape speed : not greater than 2,5 m/s
read-track : within the written track
-
azimuth alignment : not greater than 6’ between the mean write transitions and the read gap
: 1,4~m+0,2~m
write-gap length
write head saturation density : 0,34 T & 0,03 T
-
tape tension : 2,2 N AZ 0,2 N
-
recording current : test recording current
6.18.1 Typical field
The typical field of the tape shall be between 90 % and 110 % of the reference field.
Reference
Traceability to the reference field is provided by the calibration factors supplied with each Secondary Standard
Tape.
6.18.2 Signal amplitude
The average signal amplitude at the physical recording density of 972 ftpmm shall be between 70 % and 140 % of the standard
reference amplitude.
Traceability to the standard reference amplitude is provided by the calibration factors supplied with each Secondary Standard
Reference Tape.
6.18.3 Resolution
The ratio of the average signal amplitude at the physical recording density of 1 458 ftpmm to that at the physical recording
density of 972 ftpmm shall be between 80 % and 120 % of the same ratio for the Master Standard Reference Tape.
Traceability to the resolution of the Master Standard Reference Tape is provided by the calibration factors supplied with each
Secondary Standard Reference Tape.
6.18.4 Overwrite
Overwrite is the ratio of the average signal amplitude of the residual of the fundamental frequency of a tone pattern after being
overwritten at 972 ftpmm to the average signal amplitude of the 972 ftpmm signal. The average signal amplitude of the tone
pattern is the peak-to-peak amplitude of the sinusoidal signal with equal rms power.
6.18.4.1 Requirement
The overwrite for the tape shall be less than 120 % of the overwrite for the Master Standard Reference Tape.
Traceability to the overwrite of the Master Standard Reference Tape is provided by the calibration factors supplied with each
Secondary Standard Reference Tape.
Procedure
Record a tone pattern which shall be the following sequence of flux transitions:
where: al = 1,029 pm
a2 = 0,514 pm
Record a 972 ftpmm signal over the tone pattern. Measure the average signal amplitude of the residual of the fundamental
frequency of the tone pattern (one sixth of the frequency of the 972 ftpmm signal) and the average signal amplitude of the 972
ftpmm signal. Both amplitude measurements should be made using suitable filters.
6.18.5 Narrow-Band Signal-to-Noise Ratio (NB-SNR)
The narrow-band signal-to-noise ratio is the average signal amplitude rms power divided by the average integrated (side band)
rms noise power, and is expressed in dB.
6.18.5.1 Requirement
The NB-SNR ratio shall be equal to, or greater than, 30 dB when normalized to a track width of 410 pm. The normalization
factor is dB(410) = dB(W) + 10 log 410/W, where W is the track width used when measuring dB(W).
6.18.5.2 Procedure
The NB-SNR ratio shall be measured using a spectrum analyzer with a resolution bandwidth (RBW) of 1 kHz and a video
bandwidth (VBW) of 10 Hz. The tape speed shall be 762 mm/s for the frequencies specified below.
The NB-SNR ratio shall be measured as follows:
Measure the read-signal amplitude of the 972 ftpmm signal, taking a minimum of 150 samples over a minimum length
of tape of 46 m.
ii) On the next pass (read only) measure the rms noise power over the same section of tape and integrate the rms noise
power (normalizing for the actual resolution bandwidth) over the range from 332 kHz to 366 kHz.
For other tape speeds all the frequencies shall be linearly scaled.
6.19 Tape quality
The tape quality (including the effects of exposure to storage and transportation environments) is defined by the testing
requirements given in the following clauses. The following conditions shall apply to all quality testing requirements:
environment : operating environment
-
tape condition : pre-recording condition
- tape speed :2m/s
- read-track width : 410 pm
physical recording density : 972 ftpmm
write-gap length : 1,4jLm+-0,2pm
.
- azimuth alignment . not greater than 6’ between the mean write transitions and the read gap
-
write head saturation density : 0,34 T k 0,03 T
-
recording current : test recording current
- format : 18 tracks
- tape tension : 2,2 N in 0,2 N

ISO/lEC 9661:1994 (E)
6.19.1 Missing pulses
A missing pulse is a loss of read signal amplitude. A missing pulse exists when the base-to-peak read signal amplitude is 25 %,
or less, of half the average signal amplitude for the preceding 25,4 mm of tape.
6.19.2 Missing pulse zones
A missing pulse zone begins with a missing pulse and ends when 64 consecutive flux transitions are detected or a length of
1 mm of tape has been measured.
The missing pulse zone rate shall be less than one in 8 x lo6 flux transitions recorded.
6.19.3 Coincident missing pulse zones
There are two g-track groups in the 18.track format. One group comprises the odd-numbered tracks, the other group comprises
the even-numbered tracks. A simultaneous missing pulse zone condition on two or more tracks of a g-track group is a
coincident missing pulse zone.
If a coincident missing pulse zone occurs at the same time in both groups of tracks, it shall be considered as a single coincident
missing pulse zone. Its length shall begin with the start of the earliest coincident missing pulse zone and terminate with the end
of the latest coincident missing pulse zone.
No 165 m length of tape shall have more than 12 coincident missing pulse zones.
No coincident missing pulse zone shall exceed 50 mm.
Section 3 - Cartridge requirements
7 Dimensional and mechanical characteristics of the cartridge
The cartridge shall consist of the following elements:
- acase;
- a reel for the magnetic tape;
- a magnetic tape wound on the hub of the reel;
- a locking mechanism for the reel;
- a write-inhibit mechanism;
- a leader block;
- a latching mechanism for the leader block.
Dimensional characteristics are specified for those parameters deemed mandatory for interchange and compatible use of the
cartridge. Where there is freedom of design, only the functional characteristics of the elements described are indicated. In the
figures a typical implementation is presented. Third angle projection is used.
Where they are purely descriptive the dimensions are referred to three reference surfaces A, B and C forming a geometrical
trihedral (see figure 3). Where the dimensions are related to the position of the cartridge in the drive, they may be referred to
another surface of the cartridge. Figure 4 to 11 show the dimensions of the empty case.
Figure 3 is a general view of the whole cartridge;
Figure 4 shows the front side of the case which lies on reference surface A;
Figure 5 shows the top side of the case;
Figure 6 shows the rear side of the case;
Figure 7 shows the bottom side of the case which lies in reference surface C;
Figure 8 shows the side of the case which lies in reference surface B;
Figure 9 shows an enlarged view of a part of figure 4;
Figure 10 shows an enlarged cross-section of a location notch;
Figure 11 shows an enlarged cross-section of a detail of the opening of the case;
Figure 12 shows an enlarged partial cross-section of the cartridge in hand;
Figure 13 shows the same cross-section as figure 12 but of the cartridge in the drive;
Figure 14 shows schematically the teeth of the toothed rim;
Figure 15 shows two views and an enlarged cross-section of the leader block;
Figure 16 shows the fixation of the tape to the leader block, and
Figure 17 shows the leader block inserted in the case.

ISOnEC 9661:1994 (E)
71 0 Overall dimensions (figures 4 to 6)
The overall dimensions of the case shall be
I, = 125,00 mm k 0,32 mm
I, = 109,OO mm * 0,32 mm
+ 0,50 mm
I, = 24,50 mm
- 0,32 mm
The comers of the case shall be rounded off as specified by
q = 3,00 max.
r2 = 4,00 max.
r3 = 390 min.
72 0 Write-inhibit mechanism (figures 4 and 5)
The write-inhibit mechanism shall have a flat surface identified by a visual mark, e.g. a white spot, when in the position in
which writing is inhibited.
The flat surface shall be accessible through a window in the front of the case. The location and dimensions of the window are
specified by
I4 = 11,80 mm * 0,25 mm
I, = 15,60 mm 2 0,25 mm
z6 = 7,40 mm A 0,25 mm
I, = 12,00 mm 2 0,25 mm
In the write-inhibit position the flat surface of the write-inhibit mechanism shall be behind this window at a distance
I, = 2,55 mm min.
from the front side of the case.
In the write-enable position this surface shall be within 0,25 mm of the front side of the case.
The force required for the operation of the write-inhibit mechanism shall be in the range
2N to 9N
when applied tangentially to the surface of the case.
This International Standard does not prescribe the actual implementation of the write-inhibit mechanism. For example, it can
be a rotatable or a slidable element. The implementation may require a larger or additional window but shall not impair the
integrity of the case against potential contaminants.
73 l Label area of the rear side (figures 5 and 6)
On the rear side of the case there shall be a label area specified by
I, = 7,00 mm & 0,25 mm
+ 0,30 mm
Zlo = 80,OO mm
- 0,16 mm
I, 1 = 12,30 mm k 0,25 mm
Z12 = 0,50 mm * 0,25 mm
= 1,00 mm max.
‘4
ISOnEC 9661:1994 (E)
74 0 Label area of the top side (figure 5)
On the top side of the case there shall be a label area, recessed by 0,50 mm * 0,25 mm, specified by I,, Ilo, I,, and in addition
bY
I,, = 31,00 mm 2 0,25 mm
+ 0,30 mm
I,, = 75,00 mm
- 0,16 nun
75 0 Case opening (figures 4,5,7 and 9)
The case shall have an opening for the tape in which the leader block can be inserted (see also figure 17). This opening shall
be specified by
= 4,70 mm * 0,25 mm
4, = b&go mm & 0,32 mm
= 7,50 mm 2 0,25 mm
I,7
Zl, = 87,lO mm 2 0,25 mm
I,, = 4,00 mm 2 0,25 mm
= 4,oO mm * 0,25 mm
‘5
a =50"* lo
Figure 7 shows at a larger scale the details of the configuration of the case opening as seen at the right-hand side of figure 2.
= 3,9 mm 2 0,5 mm
‘61
+ 0,5 mm
ze2 = 16,9 mm
- 0,4 mm
= 3,0 mm & 0,5 mm
‘63
Z,= 11,6mm+0,5mm
= 1”+30’
Ol
02 = 20” zk 2”
76 a Locating notches (figures 7,8 and 10)
There shall be two locating notches open towards the bottom side. These location notches shall be specified by
I,, = 106,OO mm 2 0,25 mm
5,00 mm & 0,25 mm
I21 =
7,00 mm * 0,25 mm
I,2 =
Z,, = 104,OO mm 2 0,25 mm
2,50 mm 2 0,25 mm
‘24 =
p = 1”30’*30’
= 2” t, 30’
Y
77 . Locating areas (figure 7)
The bottom side of the case shall have three circular locating areas al,
a2 and a3 which shall lie in the same horizontal plane
within 0,25 mm.
Areas al and a2 shall have a diameter of 10,OO mm 2 0,25 mm. The position of their centres shall be specified by
I,, = 108,50 mm k 0,25 mm
3,50 mm A 0,25 mm
‘26 =
127 = 105,50 mm A 025 mm
Area a3 shall have a diameter of 14,00 mm k 0,25 mm. The position of its centre shall be specified by
I,, = 3 1,25 mm 2 0,25 mm
Z,, = 54,50 mm k 0,25 mm
78 0 Inside configuration of the case around the case opening (figures 7 and 11)
I
Figures 7 and 11 show the inside configuration of the case around the opening of the case. This configuration shall be defined
as follows (see also 7.10)
I,, = 3,30 mm k 0,25 mm
I,, = 18,40 mm A 0,25 mm
= 1,50 mm A 0,25 mm
‘6
= 1,50 mm 2 0,25 mm
‘7
The oblique edge of the case shall be tangential to the arc of circle defined by ‘6 at an angle of
a = 40” & 30’
79 a Other external dimensions of the case (figure 8)
P
The external form of the case shall bc
Y further specified by
Z32= 113,2 mm k 0,3 mm
Z33 = 26,00 mm * 0,25 mm
= 145,50 mm zt 0,25 mm
‘8
= 145,50 mm t, 0,25 mm
‘9
s = 30” f: 30’
7.10 Central window (figure 7)
The bottom side of the case shall have a central window. The location of its centre shall be specified by Z29 and
Z,, = 61,OO mm k 0,25 mm
Its diameter shall be
+ 2,0 mm
d, = 43,5 mm
- 1,omm
The angle with its apex at the
of this window formed by the two lines tangential to the parts in figure 7 in
cross-section shall be
8 =16”+30’
7.11 Stacking ribs
The bottom side of the case shall have two parallel stacking ribs. Their dimensions shall be
I,, = 5,00 mm k 0,25 mm
1,00 mm & 0,16 mm
‘36 =
I,, = 74,50 mm t, 0,25 mm
Their locations shall be
I,, = 31,OO mm k 0,25 mm
I,, = 7,50 mm & 0,32 mm
I,, = 79,50 mm k 0,25 mm
7.12 Flexibility of the case
The flexibility of the top and bottom sides of the case (see figure 3) is the amount of deflection observed when they are
submitted to a perpendicular force F.
7.12.1 Requirements
The amount of deflection d shall meet the following requirements:
Deflection of the top side:
0,0256 FIdI0,38 + 0,054F
Deflection of the bottom side:
0,0228 F5dS 0,38 + 0,040 F
d is the measured deflection in mm
4,5 N 5 F <, 54,0 N
7.12.2 Procedure
Measure the flexibility of the case in a universal testing machine operating in the compression mode. Use a suitable load cell
for the test. Apply a single point load with a radius of 10 mm & 1 mm on the bottom and subsequently on the top of the
cartridge at the points shown in figure 5 and figure 7, and specified by
Z6, = 86,9 mm nominal
I,, = 54,5 mm nominal
7.13 Tape reel (figures 12 and 13)
Figures 12 and 13 show the tape reel mounted within the case. Figure 12 specifies the different dimensions of the reel when
the cartridge is in hand, figure 13 when it is within the drive. For clarity the stacking ribs are not shown in figure 12 and 13.
7.13.1 Locking mechanism (figure 13)
This International Standard does not specify the actual implementation of the locking mechanism. However, functionally it
shall satisfy the following requirements in the locked position:
-
the angular resolution shall not be greater than 6”;
-
the reel shall not rotate by more than 10” when a torque not greater than 0,32 N-m is applied in the direction that will
cause the tape to unwind.
The button of the locking mechanism shall be made of nylon 6/6 with 2 % 2 1 % molybdenum disulphide.
Its dimensions shall be
= 2,0 mm * 0,5 mm
d9
d,, = 10,O mm & 0,2 mm
= 15” f: 2”
P
7.13.2 Axis of rotation of the reel
The axis of rotation of the reel shall be perpendicular to Plane P (see 7.13.7) and pass through the centre of the central window
as specified by I,9 and I,,.
7.13.3 Metallic insert
The reel shall have a metallic insert made of stainless steel (IS0 683- 13, type 3 or 7). It shall withstand a pull out force of
300 N min. Its dimensions shall be
+ 0,20 mm
d2 = 35,00 mm
- 1,20 mm
d3 = 11,15 mm k 0,05 mm
= 1,5I mm+,O,lOmm
el
Its central opening (diameter d3) shall be concentric with the axis of rotation of the reel within 0,15 mm.
The metallic insert shall be parallel to plane P within 0,15 mm.
7.13.4 Toothed rim
The reel shall have a toothed rim accessible through the central window. Its dimensions shall be
+ 0,50 mm
d4 = 36,00 mm
-0,OOIllIll
d, = 41,00 mm A 0,25 mm
= 1 1°3’ k 5’
w
7.13.5 Hub of the reel
The hub of the reel shall have a diameter
+ 0,o mm
de = 50,o mm
- 0,2 mm
Further dimensions of the hub shall be
+ 0,20 mm
Z41 = 13,05 mm
- 0,lO mm
when measured at the hub surface, and
rlo = 0,OS mm max.
The hub shall meet the following requirements:
-
the straightness of the hub surface shall be within 0,04 mm;
-
the perpendicularity to the plane P through the pitch line of the teeth of the rim (see 7.13.7) shall be within 0,07 mm;
- the ratio diameters d, Of ZiIly tW0 sections (perpendicular to the axis) to the between
of the difference in the
sections shall not exceed 0,0038
-
the rate of change across the width of the hub surface shall not exceed 0,025 mm per mm;
- the total runout of the hub related to the cylinder perpendicular to the circular pitch line (see 7.13.7) of the teeth of the
toothed rim shall not exceed 0,2 mm total indicator reading (TIR).
t
7.13.6 Relative positions
7.13.6.1 With the cartridge in hand (figure 12):
- the distance of the tip of the button of the locking mechanism to reference surface C shall be
+ 1,4omm
I42 = 1,90 mm
- 0,90 mm
the distance from the bottom surface of the metallic insert to reference surface C shall be
1s0/n3c 9661:1994 (E)
+ 1,omm
Z43 = 0,4 mm
- 0,5 mm
7.13.6.2 Whether the cartridge is in hand or in the drive (figure 12 and 13):
- the distance from the bottom surface of the metallic insert to plane P shall be
Z44 = 2,27 mm A 0,12 mm
- the distance of the inside of the lower flange of the reel to plane P shall be
Z45 = 0,65 mm * 0,09 mm
7.13.6.3 With the cartridge in the drive (figure 13):
- the distance from the tip of the button of the locking mechanism to reference surface C shall be
146 = 8,l mm + 0,2 mm
- the force required to move the button into this position shall not exceed 12,25 N
- the distance from the centreline of the tape to reference surface C shall be
Zd7 = 12,25 mm nominal
- the distance from the reference surface C to Plane P (see 7.14.7) shall be
I, = 5,04 mm * 0,20 mm
7.13.7 Characteristics of the toothed rim (figure 12)
The toothed rim shall comprise 60 teeth spaced at an angle of
6’ t, 5’ non-cumulative
The teeth are specified at the pitch diameter d, by
1,, = 4 mm nominal
Z49 = 2 mm nominal
= 30” nominal
(P
The pitch line is the circumference of the teeth taken at the distance Z49. The plane in which it lies is the plane P.
The blend radius at the bottom of the teeth shall be
rll = 0,25 mm max.
The blend radius at the tip of the teeth shall be
0,lO mm S r12 S 0,30 mm
7.14 Leader block (figure 15)
The leader block shall have the following dimensions:
I,, = 31,80 mm t, 0,04 mm
= 6,8 mm & 0,l mm
I,1
Z52=21,8mm+0,2mm 4
+0,06mm
I,, = lo,93 mm
- 0,08 mm
I,, = 5,46 mm =t 0,lO mm
I,, = 6,00 mm * 0,25 mm
ISOnEC 9661:1994 (E)
+ 0,o mm
Z56 = 165 mm
- 0,2
...