ISO/IEC 10777:1991
(Main)Information technology — 3,81 mm wide magnetic tape cartridge for information interchange — Helical scan recording — DDS format
Information technology — 3,81 mm wide magnetic tape cartridge for information interchange — Helical scan recording — DDS format
Technologies de l'information — Cartouche de bande magnétique de 3,81 mm de large pour l'échange d'information — Enregistrement par balayage en spirale — Format DDS
General Information
Relations
Standards Content (Sample)
I NTER NATIONAL ISO/IEC
STANDARD I0777
First edition
1991 -09-1 5
Information technology - 3,81 mm wide
magnetic tape cartridge for information
interchange - Helical scan recording -
DDS format
Technologies de l'information - Cartouche de bande magnétique de 3,81 mm de
large pour l'échange d'information - Enregistrement par balayage en spirale -
Format DDS
Reference number
ISO/IEC 10777 : 1991 (E)
---------------------- Page: 1 ----------------------
ISOiIEC 10777:1991 (E)
Contents
Page
1
Section 1 - General
1
1 Scope
1
2 Conformance
1
2.1 Magnetic tape cartridge
1
2.2 Generating system
1
2.3 Receiving system
2
3 Normative references
2
4 Definitions
2
4.1 Absolute Frame Number (AFN)
2
4.2 automatic track finding (ATF)
2
4.3 Area ID
2
4.4 Average Signal Amplitude
2
4.5 azimuth
2
4.6 back surface
2
byte
4.7
2
cartridge
4.8
2
4.9 Channel bit
2
4.10 Data Format ID
2
4.1 1 Early Warning Point (EWP)
2
4.12 End of Data (EOD)
2
4.13 Error Correcting Code (ECC)
2
4.14 flux transition position
2
4.15 flux transition spacing
2
frame
4.16
2
4.17 housekeeping frame
3
4.18 Logical Beginning of Tape (LBOT)
3
4.19 magnetic tape
3
Master Standard Amplitude Calibration Tape
4.20
O ISO/IEC 1991
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 0 Case postale 56 0 CH-I211 Genève 20 0 Switzerland
Printed in Switzerland
ii
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ISO/IEC 10777:1991 (E)
4.21 3
Master Standard Reference Tape
3
4.22 Optimum Recording Field
3
Partition boundary
4.23
3
4.24 Physical Beginning of Tape (PBOT)
3
4.25 Physical End of Tape (PEOT)
3
4.26 physical recording density
3
4.27 pre-recording condition
3
4.28 record
3
4.29 Reference Recording Field
3
Secondary Standard Amplitude Calibration Tape
4.30
3
Secondary Standard Reference Tape
4.31
3
4.32 separator
4
4.33 Standard Reference Amplitude
4
4.34 Tape Reference Edge
4
4.35 Test Recording Current
4
4.36 track
4
4.37 Virtual End of Tape (VEOT)
4
5 Environment and safety
4
5.1 Testing environment
4
5.2 Operating environment
4
5.3 Storage environment
5
5.4 Transportation
5
5.5 Safety
5
5.6 Flammability
5
Section 2 - Requirements for the case
5
of the case
6 Dimensional and mechanical characteristics
5
General
6.1
6
6.2 Overall dimensions (figures 6 and 7)
6
6.3 Loading grip (figure 6)
6
6.4 Holding areas (figure 6)
6
6.5 Notches of the lid (figures 5 and 8)
7
Lid dimensions (figures 6 to 8)
6.6
7
6.7 Optical detection of the Beginning and End of Tape (figures 9 and 12)
8
6.8 Bottom side (figures 10 and 11)
8
Locking mechanism of the slider
6.8.1
9
Access holes
6.8.2
9
Recognition, Sub-datums, and Write-inhibit Holes
6.8.3
11
Datum Holes
6.8.4
11
6.8.5 Access room for tape guides
12
6.8.6 Holes for accessing the hubs
12
internal structure of the lower half (figure 12)
6.8.7
13
Light path (figure 12)
6.8.8
13
Support Areas (figure 13)
6.8.9
14
Datum Areas (figure 13)
6.8.1 O
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ISOhEC 10777:1991 (E)
Relationship between Support and Datum 4reas and Reference
6.8.1 1
14
Plane 2 (figure 14)
14
6.9 Hubs (figures 15, 16)
15
6.10 Leader and trailer attachment
15
6.1 1 lnterface between the hubs and the drive spindles (figure 17)
15
6.12 Opening of the lid (figure 18)
15
6.13 Release of the hub locking mechanism (figures 19, 20)
16
6.14 Label areas (figure 21, 22)
27
Section 3 - Requirements for the unrecorded tape
27
7 Mechanical, physical and dimensional characteristics of the tape
27
7.1 Materials
27
7.2 Tape length
27
7.2.1 Length of magnetic tape
27
7.2.2 Length of leader and trailer tapes
27
Tape width
7.3
27
Discontinuities
7.4
27
7.5 Total thickness
27
7.6 Longitudinal curvature
27
7.7 Cupping
28
7.8 Coating adhesion
28
7.9 Layer-to-layer adhesion
29
7.10 Tensile strength
29
7.10.1 Breaking strength
29
7.10.2 Yield strength
29
7.1 1 Residual elongation
29
7.12 Electrical resistance of coated surfaces
30
Light transmittance of the tape
7.13
30
8 Magnetic recording characteristics
31
8.1 Optimum Recording Field
31
8.2 Signai amplitude
31
8.3 Resolution
31
8.4 Overwrite
31
8.4.1 Physical recording densities of 750,6 ftpmm and 3002 ftpmm
32
8.4.2 Physical recording densities of 83,4 ftpmm and 1001 ftpmm
32
8.5 Ease of erasure
32
8.6 Tape quality
32
8.6.1 Missing pulses
32
8.6.2 Missing pulse zone
32
8.7 Signal-to-noise ratio (S/N) characteristic
iv
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ISODEC 10777:1991 (E)
33
iection 4 - Requirements for an interchanged tape
33
Format
33
9.1 General
33
9.2 Basic Groups
34
9.2.1 Group Information Table
37
9.2.2 Block Access Table
39
9.3 Sub-Groups
39
9.3.1 G1 Sub-Group
40
9.3.2 G2 Sub-Group - Randomizing
40
9.3.3 G3 Sub-Group
42
9.3.4 G4 Sub-Group
46
9.3.5 Main Data Block
48
9.4 Sub Data Area
48
Pack Item No. 1
9.4.1
49
9.4.2 Pack Item No. 2
50
9.4.3 Pack Item No. 3
51
9.4.4 Pack Itdm No. 4
53
9.4.5 Pack item No. 5
54
No. 6
9.4.6 Pack Item
55
Pack Item No. 7
9.4.7
56
Pack Item No. 8
9.4.8
56
9.4.9 Sub Data Block
Method of recording
10.1 Physical recording density
Long-term average bit cell length
10.2
Short-term average bit cell length
10.3
10.4 Rate of change
10.5 Bit shift
10.6 Read signal amplitude
10.7 Maximum recorded levels
Track geometry
61
11.1 Track configuration
62
11.2 Average track pitch
62
Variations of the track pitch
11.3
62
11.4 Track width
63
Track angle
11.5
63
Track edge linearity
11.6
63
Track length
11.7
63
11.8 Ideal tape centreline
63
11.9 Azimuth angles
63
Recording of blocks on the tape
63
12.1 Recorded Main Data Block
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ISODEC 10777:1991 (E)
63
12.2 Recorded Sub Data Block
63
Margin Blocks, Preamble Blocks and Postamble Blocks
12.3
63
12.4 Spacer Blocks
64
Format of a track
13
64
13.1 Track capacity
64
13.2 Positioning accuracy
64
13.3 Tracking scheme
67
14 Layout of a Single Data Space tape
67
14.1 Device Area
68
14.2 Reference Area
68
Position Tolerance Band No. 1
14.3
68
14.4 System Area
68
14.4.1 System Preamble
14.4.2 System Log
68 c
14.4.3 System Postamble
68
Position Tolerance Band No. 2
14.4.4
68
14.4.5 Vendor Group Preamble
68
14.5 Data Area
69
14.5.1 Vendor Group
69
14.5.2 Recorded Data Group
69
14.5.3 ECC3
70
14.5.4 Multiple recorded instances
70
14.5.5 Repeated frames
71
14.5.6 Appending and overwriting
72
14.6 EOD Area
73
14.7 Post-EOD Area
73
Early Warning Point - EWP
14.8
73
14.9 Initialization
15 Layout of a Partitioned tape
73 0
74
15.1 Overall magnetic tape layout
74
15.1.1 Device Area
74
15.1.2 Partition 1
75
15.1.3 Partition O
76
15.2 Area ID
System Area Pack Items No. 3 and No. 4 76
15.3
76
15.4 Empty Partition
76
15.5 Initialization of Partitioned Tapes
76
16 Housekeeping frames
16.1 Amble Frames 77
16.2 System Log Frames 77
16.3 Tape Management Frames
77
vi
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ISO/IEC 10777:1991 (E)
Annexes
Annex A - Measurement of the light transmittance of the prisms 79
81
Annex B - Recognition Holes
Annex C - Means to open the lid 82
83
Annex D - Measurement of light transmittance of tape and leaders
86
Annex E - Measurement of Signal-to-Noise Ratio
Annex F - Method for determining the nominal and the maximum allowable
87
recorded levels
88
Annex G - Representation of 8-bit bytes by 10-bit patterns
94
Annex H - Measurement of bit shift
97
Annex J - Recommendations for transportation
98
Annex K - Method of measuring track edge linearity
99
Annex L - Read-After-Write
1 O0
Annex M - Example of the content of a Basic Group No. O
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Foreword
I
IS0 (the International Organization for Standardization) and IEC (the International
Electrotechnical Commission) form the specialized system for worldwide standardiz-
ation. 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, ISOAEC 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 75 070 of the national bodies casting
a vote.
International Standard ISOAEC 10777 was prepared by the European Computer
Manufacturers Association (as Standard ECMA-139) 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, D to H and K form an integral part of this International Standard.
Annexes B, C, J, L and M are for information only.
Patents
During the preparation of the ECMA standard, information was gathered on patents
upon which application of the standard might depend. Relevant patents were identified
as belonging to Hewlett Packard Limited and the Sony Corporation. However, neither
ECMA, nor ISOAEC can give authoritative or comprehensive information about
evidence, validity or scope of patent and like rights. The patent holders have stated that
licences will be granted under reasonable and non-discriminatory terms. Communi-
cations on this subject should be addessed to
Hewlett Packard Limited
Computer Peripherals Bristol
Filton road
Stoke Gifford
Bristol BS12 642
United Kingdom
Sony Corporation
Licensing and Trademark Division
6-7-35 Kitashinagawa
Shinagawa-ku
Tokyo 141
Japan
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ISO/IEC 10777:1991 (E)
Introduction
This International Standard specifies the characteristics of a 3,81 mm wide magnetic tape
cartridge to enable interchangeability of such cartridges. The format used is known as
Digital Data Storage (DDS).
---------------------- Page: 9 ----------------------
ISO/IEC 10777:1991 (E)
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.
IS0 W527: 1966, Plastics - Deternlination of tensile properties.
IS0 1302: 1978, Technical Drawings - Method of indicating Surface Texture on Drawings.
IEC 950: 1988, Safety of lnformarion Technology Equipment (ITE).
4 Definitions
For the purpose of this International Standard, the following definitions apply.
Absolute Frame Number (AFN) : A sequence number, encoded in the frame.
4.1
automatic track finding (ATF) : The method by which tracking is achieved.
4.2
4.3 Area ID : An identifier defining the area of the tape and specifying the types of frame written.
4.4 Average Signal Amplitude : The average peak-to-peak value of the output signal from the read
head at the fundamental frequency of the specified physical recording density over a minimum of
7,s mm of track, exclusive of missing pulses.
azimuth : The angular deviation, in degrees, minutes and seconds of arc, made by the mean flux
4.5
transition line with the line normal to the centreline of the recorded track.
4.6 back surface : The surface of the tape opposite to the magnetic coating which is used to record
data.
4.7 byte : An ordered set of bits acted upon as a unit.
4.8 cartridge : A case containing magnetic tape stored on twin hubs.
4.9 Channel bit : A bit after 8-10 transformation.
4.10
Data Format ID : An identifier specifying which data format is being used on the tape.
4.11 Early Warning Point (EWP) : A point along the length of the tape at which warning is given of the
0
approach, in the forward direction of tape motion, of the partition boundary or of the Physical End
of Tape.
4.12 End of Data (EOD) : The point on the tape at the end of the group which contains the last user
data.
4.13 Error Correcting Code (ECC) : A mathematical algorithm yielding check bytes used for the
detection and correction of errors.
4.14 flux transition position : That point which exhibits maximum free-space flux density normal to the
tape surface.
4.15 flux transition spacing : The distance along a track between successive flux transitions.
4.16 frame : A pair of adjacent tracks with azimuths of opposite polarity, in which the track with the
positive azimuth precedes that with the negative azimuth.
4.17
Housekeeping Frame : A frame which contains no user data and which is identified as such by the
values in the data fields therein.
2
---------------------- Page: 10 ----------------------
ISO/IEC 10777:1991 (E)
1.18 Logical Beginning of Tape (LBOT) : The point along the length of the tape where a recording of
data for interchange commences.
1.19 magnetic tape : A tape which will accept and retain the magnetic signals intended for input, output
and storage purposes on computers and associated equipment.
1.20 Master Standard Amplitude Calibration Tape : A pre-recorded tape on which the standard signal
amplitudes have been recorded in the tracks of positive azimuth, 23,O pm wide, at nominal track
pitch, on an AC-erased tape.
NOTE 1 - The tape includes recording made at X3,4 ftpmm, 333,h ftpmm, 500,4 ftpmm, IOOI ftpmm and 1501 ftprnm.
NOTE 2 - The Master Standard Amplitude Calibration Tape has been established by Sony Corporation.
i.21 Master Standard Reference Tape : A tape selected as the standard for Reference Recording Field,
Signal Amplitude, Resolution, Overwrite and Signal-to-Noise Ratio.
NOTE 3 - The Master Standard Reference Tape has been established by Sony Corporation.
1.22 Optimum Recording Field : in the plot of Average Signal Amplitude against the recording field at
the physical recording density of 3002 ftpmm, the field that causes the maximum Average Signal
Amplitude.
1.23 Partition boundary : The point along the length of a magnetic tape at which Partition 1 ends and
Partition O commences.
1.24 Physical Beginning of Tape (PBOT) : The point where the leader tape is joined to the magnetic
tape.
: The point where the trailer tape is joined to the magnetic tape.
1.25 Physical End of Tape (PEOT)
1.26 physical recording density : The number of recorded flux transitions per unit length of track,
expressed in flux transitions per millimetre (ftpmm).
1.27 pre-recording condition : The recording levels above which a tape intended for interchange shall
not previously have been recorded.
1.28 record : Related data treated as a unit of information.
Reference Recording Field : The Optimum Recording Field of the Master Standard Reference
1.29
Tape.
1.30 Secondary Standard Amplitude Calibration Tape : A tape pre-recorded as defined for the Master
Standard Amplitude Calibration Tape; the outputs are known and stated in relation to those of the
Master Standard Amplitude Calibration Tape.
NOTE 4 - Secondary Standard Amplitude Calibration Tapes can be ordered from Sony Corporation, Audio Device
Business Department, Component Marheting Group, 4-10-18, Takanawa, Minato-ku, Tokyo 108, Japan, under Part
Number TY-700OG until the year 2001). It is intended that these be used for calibrating tertiary reference tapes for use in
routine calibration.
1.31 Secondary Standard Reference Tape : A tape the performance of which is known and stated in
relation to that of the Master Standard Reference Tape.
NOTE 5 - Secondary Standard Reference Tapes can be ordered from Sony Corporation, Major Customer Division,
Magnetic Products Group, 6-7-35, Kitashinagawa, Shinagawa-ku, Tokyo 141, Japan, under Part Number RSD 1079 until
the year 2000. It is intended that these be u5ed for calibrating tertiary reference tapes for use in routine calibration.
1.32 Separator : A record containing no user data, which is used to separate data.
3
---------------------- Page: 11 ----------------------
ISO/IEC 10777:1991 (E)
4.33 Standard Reference Amplitude : The Average Signal Amplitude from the tracks of positive
azimuth of the Master Standard Amplitude Calibration Tape at a specified physical recording
density.
4.34 Tape Reference Edge : The bottom edge of the tape when viewing the recording side of the tape,
with the PEOT to the observer's right.
4.35 Test Recording Current : The current that produces the Reference Recording Field.
4.36 track : A diagonally positioned area on the tape along which a series of magnetic signals may be
recorded.
4.37 Virtual End of Tape (VEOT) : The point along the length of the magnetic tape within Partition 1
which defines the end of the part of Partition 1 which is usable for recording data for interchange.
5 Environment and safety
Unless otherwise stated, the conditions specified below refer to the ambient conditions of the air
immediately surrounding the cartridge.
5.1 Testing environment
Unless otherwise stated tests and measurements made on the tape cartridge to check the
requirements of this international Standard shall be carried out under the following conditions:
: 23 "C $: 2 "C
Temperature
Relative Humidity : 40 70 to 60 %
Conditioning period
before testing : 24 hours
5.2 Operating environment
Cartridges used for data interchange shall be capable of operating under the following
conditions:
: 5 "C to 45 "C
Temperature
: 20 5% to 80 %
Relative Humidity
Wet Bulb Temperature : 26 "C max.
There shall be no deposit of moisture on or in the cartridge.
Conditioning before operating:
If a cartridge has been exposed during storage and/or transportation to a condition outside the
above values, before use the cartridge shall be conditioned in the operating environment for a
time at least equal to the period during which it has been out of the operating environment, up
to a maximum of 24 hours.
NOTE h - Rapid variations of temperature should be avoided.
5.3 Storage environment
For long-term or archival storage of cartridges the following conditions shall be observed:
: 5 "C to 32 "C
Temperature
: 20 % to 60 96
Relative Humidity
: 26 "C max.
Wet Bulb Temperature
---------------------- Page: 12 ----------------------
ISO/IEC 10777:1991 (E)
The stray magnetic field at any point on the tape shall not exceed 4000 Nm. There shall be no
deposit of moisture on or in the cartridge.
5.4 Transportation
Recommended limits for the environment to which a cartridge may be subjected during trans-
portation, and the precautions to be taken to minimize the possibility of damage, are provided in
annex J.
5.5 Safety
The cartridge and its components shall satisfy the requirements of IEC 950.
5.6 Flammability
The cartridge and its components shall be made from materials, which if ignited from a match
flame, do not continue to burn in a still carbon dioxide atmosphere.
Section 2 - Requirements for the case
6 Dimensional and mechanical characteristics of the case
6.1 General
The case of the cartridge shall comprise:
- an upper half,
- a lower half,
-
a slider movably mounted on the lower half,
-
a lid pivotally mounted on the upper half.
In the drawings, using third angle projection, an embodiment of the cartridge is shown as an
example.
Figure 1 is a perspective view of the cartridge seen from top.
Figure 2 is a perspective view of the cartridge seen from bottom.
Figure 3 is a partial view of the rear side.
Figure 4 is a schematic view showing the Reference Planes X, Y and 2.
Figure 5 shows the front side.
Figure 6 shows the top side with the lid in closed position.
Figure 7 shows the left side.
Figure 8 shows the top side with the lid in open position.
Figure 9 shows the left side with the lid in open position.
Figure 10 shows the bottom side with the lid and the slider in closed position.
Figure 11 shows the bottom side with the lid and the slider in open position.
Figure 12 is a view from the top of the inside of the lower half with the upper half
removed.
Figure 13 is a view of the bottom half with the lid and the slider in open position.
Figure 14
is a view of the left side with the lid and the slider in open position.
Figure 15 is a top view of a hub.
5
---------------------- Page: 13 ----------------------
ISOflEC 10777:1991 (E)
Figure 16 is a side view of a hub with partial cross-section.
Figure 17 is a partial cross-section through a hub and both halves of the case showing the
interface with the drive spindle.
Figure 18 shows at a larger scale the lid in the open position.
Figure 19, 20 show at a larger scale the functional relationship between the lid and the locking
mechanism of the hubs.
Figure 21, 22 show the label areas on the top and the rear side.
The dimensions are referred to three orthogonal Reference Planes X, Y and Z (figure 4).
6.2 Overall dimensions (figures 6 and 7)
The overall dimensions of the case with the lid in the closed position shall be:
LI = 73,O mm f 0,3 mm
L2 = 54,O mm f 0,3 mm
L3 = 10,5 mm f 0,2 mm
The edges formed by the rear side and the left and right sides shall be rounded off with a radius
RI = 1,5 mm max.
The two edges of the lid shall be rounded off with a radius
R2 = 0,5 mm max.
6.3 Loading grip (figure 6)
The top side shall have a loading grip for loading and positioning the cartridge into the drive.
The position and dimensions of the loading grip shall be
L4 = 25,5 mm f 0,3 mm
Lg = 10mm min.
L6 = 5,O mm f 0,2 mm
L7 = 2,O mm min.
The depth of the loading grip below the surface of the top side shall be
+ 0,2 mm
0~ mm - O,O mm
6.4 Holding areas (figure 6)
The two areas shown shaded in figure 6 shall be the areas along which the cartridge shall be held
down when inserted in the drive. Their positions and dimensions shall be
Le = 6,O mm f 0,l mm
L9 = 5,O mm f 0,l mm
6.5 Notches of the lid (figures 5 and 8)
The lid shall have two pairs of notches.
The first pair of notches, the slider lock release notches, allows elements of the drive to release
the locking mechanism of the slider. The positions and dimensions of these notches shall be
---------------------- Page: 14 ----------------------
ISOOEC 10777:1991 (E)
Llo = 0,4 mm max.
L11 = 3,O mm min.
L12 = 1,2 mm f 0,l mm
Li3 = 49,8 mm f 0,2 mm
The second pair of notches, the slider movement notches, allows elements of the drive to move
the slider from the closed to the open position (see also 6.8.1). The positions and dimensions of
these notches shall be
Li1 = 3,0 mm min.
Li4 = 0,9 mm min.
Li5 = 73 mm le 0,l mm
Llh = 36,OO mm I 0,15 mm
6.6 Lid dimensions (figures 6 to 8)
The lid is shown in the closed position in figure 6 and 7. Its dimensions shall be
Li7 = 1,2 mm _+ O,] mm
Llg = 6,8 mm f 0,4 mm
Li9 = 1,l mm f 0,l mm
L20 = 2,O mm I 0,l mm
L~I = 6,4 mm f 0,2 mm
L22 = 1,5 mm f 0,l mm
R3 = 6,8 mm le 0,4 mm
The lid shall have a chamfer of 45" by
L23 = 1,5 mm f 0,l mm
-24 shown in figure 7, which
There shall be a dimensional relationship between the height
includes the slider and the upper half, and the height L25 of the lid. When a vertical force of 1 N
is exerted on the upper half the following condition shall be met.
L24 = 10,5 mm I 0,2 mm
L25 5 L24
When no force is exerted
L24 = 10,9 mm max.
In figure 8 the lid is shown in the open position. The distance from the front edge of the lid to
the rear side shall be
L26 = 55,s mm le 0,3 mm.
Optical detection of the Beginning and End of Tape (figures 9 and 12)
6.7
Means for the optical detection of the beginning and end of tape shall be provided. These shall
consist of a pair of windows on the left and right sides of the case (see also figure 18). The
design of these windows allows this detection for two different drive designs:
- either a light source and a detector are provided in the drive on each side of the cartridge, in
which case the light enters the case through the upper windows, falls on a prism (see section
7
---------------------- Page: 15 ----------------------
ISODEC 10777:1991 (E)
A-A) mounted inside the case, which reflects this light so that it goes through the tape and
falls on the detector through the lower window; the light transmittance of the prism shall be
greater than 50% of that of a reference prism when measured as specified in annex A,
-
or, the light of a light source within the drive passes through the tape from inside the
cartridge and falls through the lower windows onto the detectors placed on each side of the
case.
The positions and dimensions of these windows allow the cartridge to be used with drives imple-
menting either system, they shall be
L27 = 6.20 mm f 0,lO mm
L2x = 7,65 mm f 0,lO mm
L30 = 3,9 mm t 0,l mm
L31 = 1,8 mm f 0,l mm
L32 = 7,O mm f 0,2 mm
L33 = 2,5 mm min.
Dimension L32 specifies the position of the rear eLge of the windows relative to Reference Plane
Y. Dimension L33 shall be measured relative to this rear edge.
10 and 11)
6.8 Bottom side (figures
The bottom side is shown in figure 10 with the lid and the slider in the closed position and in
figure 11 with both in the open position.
The dimension L34 of the bottom half, L35 of the slider and L36 of the lid shall satisfy the
following conditions
L34 = 73,O mm f 0,3 mm
L35 5 L34
L36 L34
Locking mechanism of the slider
6.8.1
The cartridge shall have a locking mechanism for the slider which locks it in the closed and
open positions. The design of this mechanism is not specified by this International Standard,
except for the different forces acting on the slider, and for its detent.
The slider shall be spring-loaded by a spring holding it in the closed position when it is
unlocked. The force required to operate the slider shall not exceed 2 N.
The slider shall have two grooves with an opening at each end. The detent of the locking
mechanism shall protrude through these openings so as to hold the slider in both open and
closed positions. The detent shown in cross-section C-C is only an example of implementation.
The grooves are parallel to Reference Plane 2 and aligned with the slider lock release notches
of the lid. The positions and dimensions of the grooves and of the openings for the detent of
the locking mechanism when the slider is in the closed position shall be
L37 = 1,2 mm t 0,l mm
L38 = 49,8 mm I 0,2 mm
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ISODEC 10777:1991 (E)
L39 = 10,O mm I 0,l mm
+ 0,5 mm
L40 = 290 mm - 0,o mm
L4l = 3,O mm min.
L42 = 1,5 mm min.
L43 = 0,8 mm f 0,l mm
X = 450 min.
L45 = 0,65 mm I 0,05 mm
The position and dimensions of the openings for the detent when the slider is held in the open
position are determined by L39, L40, L43 and L44.
In the closed position of the slider, the maximum force to be exerted on the detent in a direc-
Z and over a stroke of 0,65 mm shall be 0,5 N max.
tion perpendicular to Reference Plane
In the open position of the slider the holding force shall be 0,3 N min.
6.8.2 Access holes
The slider shall have two circular access holes (see section B-B) which, in the open position of
the slider, allow penetration of the drive spindles into the hubs. The diameters of these access
holes shall be
dl = 10,O mm f 0,2 mm
d2 = 12,O mm max.
Recognition, Sub-datums, and Write-inhibit Holes
6.8.3
The bottom half shall have a number of holes on an edge at its rear. This edge shall be
defined by
L4 = 45,2 mm f 0,2 mm
L47 = 49,2 mm I 0,2 mm
The centres of these holes lie on a line perpendicular to Reference Plane Y at a distance from
Reference Plane X of
L48 = 47,2 mm t 0,2 mm
6.8.3.1 Recognition Holes
There shall be four Recognition Holes numbered from 1 to 4 as shown in figure 10. Their
positions and dimensions shall be
d3 = 2,5 mm f 0,l mm
L49 = 1,0 mm f 0,l mm
,550 = 56,O mm f 0,3 mm
L51 = 4,O mm t 0,l mm
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ISODEC 10777:1991 (E)
L52 = 1,0 mm f O,] mm
L53 = 3,O mm min.
All Recognition Holes shall have the cross-section shown in cross-section F-F in figure 11
for Recognition Hole No. 1.
One of the two cross-sections F-F shows a Recognition Hole closed by means of a plug, the
other shows it with the plug punched out. These plugs shall withstand an applied force of
0,5 N max. without being punched out.
This International Standard prescribes the following states of these holes:
Recognition Holes No. 1 to No. 3 shall be closed
Recognition Hole No. 4 may be open or closed
of the states of the Recognition Holes No. 1, No. 2 and No. 3 are
Other combinations
reserved for future applications (see annex B).
6.8.3.2 Write-inhibit Hole
The position and dimensions of the Write-inhibit Hole shall be
d4 = 2,5 mm 1: O,] mm
L50 = 56,O mm k 0,3 mm
is open, recording on the tape is inhibited, when it is closed
When the Write-inhibit Hole
recording is enabled.
The Write-inhibit Hole shall have the cross-sec
...
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