COORDINATION OF THREE PROPOSED STANDARDS FOR MAGNETIC MEDIA

• Document Type: CREST
• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): CIA-RDP83T00573R000600200003-4
• Release Decision: RIPPUB
• Original Classification: K
• Document Page Count: 103
• Document Creation Date: December 12, 2016
• Document Release Date: April 24, 2002
• Sequence Number: 3
• Publication Date: September 30, 1976
• Content Type: MF

Approved For Releas 2105
r ca"
1976 September 30
1t%Ji T$~TrSQ rffl=m --4coMMERCE
ationa ureau of Standards
Washington, D.C. 20234
MEMORANDUM FOR FIPS Points of Contact
From: Harry S. White, Jr.
Associate Director for ADP Stal/dards
Subject: Coordination of Three Proposed Standards for Magnetic Media
Enclosed, for your consideration are three proposed Federal Information
Processing Standards (FIPS) for Magnetic Tape Cassettes, Tape
Cartridges, and Magnetic Tape (6250 CPI, Group Coded Recording). These
three proposed FIPS are the Federal adoption of voluntary industry
standards developed under the auspices of the American National
Standards Institute. (These proposals were provided to you earlier,
but had to be ignored due to problems in the reproduction process.
Reference my memoranda of September 15 and September 22, subject as
above.)
In order to ensure that all agencies have an opportunity to present
their views, NBS is soliciting your comments on these proposals. 7.C
you find that your agency cannot concur with these proposed standards,
please indicate specific changes that you feel are needed.
Also, please indicate to what extent these proposed standards are
applicable to your agency and the expected impact these will have on
increasing the efficiency and economy of your ADP systems operations.
Please submit your comments within ninety days of the date of this
memorandum to: Associate Director for ADP Standards
Institute for Computer Sciences and Technology
National Bureau of Standards
Washington, D.C. 20234
Concurrences will be assumed if a response is not received by this date.
Enclosures
cc: State Information Systems Coordinators
71,5 YEARS
NBS
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eaaera n orma ion
Processing Standards Publication
Announcing the Standard for
RECORDED MAGNETIC TAPE CARTRIDGE FOR INFORMATION INTERCHANGE,
4-TRACK, 6.30 mm (0.250 in), 63 bpmm (1600 bpi), PHASE ENCODED
Federal Information Processing Standards Publications are issued by the
National Bureau of Standards pursuant to the Federal Property and Administra-
tive Services Act of 1949 as amended, Public Law 89-306 (79 Stat. 1127),
Executive' Order 11717 (38 FR 12315), dated May 11, 1973), and Part 6 of
Title 15 CFR (Code of Federal Regulations).
Name of Standard. Recorded Magnetic Tape Cartridge for Information Inter-
change, 4-Track, 6.30 mm (0.250 in), 63 bpmm (1600 bpi), Phase Encoded
(FIPS PUB _ ).
Category of Standard. Hardware Standard, Interchange Codes and Media.
Explanation. This standard specifies the recorded characteristics for a
6.30 mm (0.250 in) wide magnetic tape cartridge with either one, two, or
four serial data tracks in-j rder.to provide for data interchange between
information processing. systems, communication systems, and associated
equipment at a recording density of 63 bits per millimeter (1600 bits per
inch) using phase encoding techniques. This standard is one of a series
of Federal Standards implementing the Federal Standard Code for Information
Interchange (FIPS 1) on magnetic tape media.
Approving Authority. Secretary of Commerce.
Maintenance Agency. Department of Commerce, National Bureau of Standards
nstitute for Computer Sciences and Technology).
Cross Index.
a. American National Standard X3.56-1976, Recorded Magnetic Tape
Cartridge for Information Interchange, 4-Track, 0.250 in (6.30 mm), 1600 bpi
(63 bpmm), Phase Encoded.
b. American National Standard X3.55-1976, Unrecorded Magnetic Tape
Cartridge for Information Interchange.
c. FIPS PUB 1, Federal Standard Code for Information Interchange.
d. FIPS PUB 35, Code Extension Techniques in 7 or 8 Bits.
e. At the time of publication of this FIPS PUB, a standard for parallel,
4-track, recording for a 6.30 mm (0.250 in) magnetic tape cartridge was under
development by the American National Standards Institute. This voluntary
industry standard, when avail able, will be considered for Federal adoption
as a FIPS.
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Applicability. This standard is applicable to th.e acquisition and use to
all magnetic tape cartridge recording and reproducing equipments employing
6.30 millimeter (0.250 inch) wide magnetic tape with one, two, or four
independent serial data tracks at recording densities of 63 bits per milli-
meter (1600 bits per inch) using phase encoding. Federal information
processing systems employing such equipment, including associated software,
shall provide the capability to accept and generate recorded magnetic tape
cartridges in compliance with the requirements set forth in this standard.
i
Specifications. Witte one exception, this standard adopts the specifications
set forth in American National Standard X3.56-1976, Recorded Magnetic Tape
Cartridge for Information Interchange, 4-Track, 0.250 in (6.30 mm), 1600 bpi
(63 bpmm), Phase Encoded. This exception changes the last sentence of
paragraph 4.3.1 to read: "The eighth position shall be a zero when recording
ASCII (FIPS 1) characters and can be other than zero when recording dense
numeric, binary or extended (FIPS 35) code representations.
Implementation Schedule. All applicable equipment ordered on or after the
date of this FIPS PUB must be in conformance with this standard unless a
waiver has been obtained in accordance with the procedure described below.
Federal departments and agencies are responsible for issuing specific internal
implementation instructions for the use by this standard by their organiza-
tional units and for assuring that copies of this FIPS PUB and its associated
technical specification (American National Standard X3.56-1976) are made
available to all effected parties.
Special Information. Federal standards and/or specifications for unrecorded
magnetic tape cartridges will be developed and issued by the General Services
Administration. Until such time as these are available, American National
Standard X3.55-1976, Unrecorded Magnetic Tape Cartridge for Information Inter-
change, should be cited in Federal procurements.
Also GSA will provide terminology for use of this standard in Federal ADP
acquisitions. This terminology will be incorporated in the Federal Property
Management Regulations (Title 41, Subtitle C, Part 101, Subpart 101-32.13,
Code of Federal Regulations).
Qualifications. None.
Waiver Procedures. (The approval and processing of waivers to Federal
Information Processing Standards is currently being reviewed by the Department
of Commerce and will be provided in the printed version of this FIPS PUB.)
Where to Obtain Copies of the Specifications.
(To be completed by NBS.)
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X3.3(
X3B5/75-44
1975 April 16
Rev of X3B5/75-19
Editorially revised
1976 April 14
1976 June 9
Fifth Draft
Proposed
American National Standard
RECORDED MAGNETIC TAPE CARTRIDGE FOR
INFORMATION INTERCHA14GE
4 TRACK, 0.250 Inch (6.30mm), 1600 BPI (63bpmm), Phase Encoded
This draft standard is published for a four-month period of public
review and comment. Comments received during this period will be
considered and answered. The draft standard, revised as necessary,
will then be submitted to American National Standards Committee X3
for letter ballot. Upon completion of the ballot, the proposal
will be forwarded to the American National Standards Institute for
approval as an American National Standard.
Comments should be returned as noon as possible but not later than
1975 November 19, addressed to:
CBEMMA/Secretary X3
1828"L" Stim
Washington DC 20036
Prepared by
Technical Committee X3B5 - Magnetic Tape Cassettes
American National Standards Committee
X3 - Computers !Ind Information Processing
Secretariat: Computer and. Business Equipment Manufacturers Association
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(This Foreword is not part of the American National Standard
Recorded Magnetic Tape Cartridge for information Interchange,
1600 bpi (63 bpmm) Phase Encoded, X3.XX-19XX)..
This AN Standard presents the standard technique for recording
the USA Standard Code for Information Interchange X3.4-1968'
(.ASCII) and amendments thereto on a magnetic tape cartridge at
1600 bpi (63bpmm) using phase recording techniques. It is one of a
series of standards implementing the ASCII in media.
Related standards define more fully the physical and magnetic
properties of the magnetic tape cartridge and specify a stand-
ard record format and labels.
The X3B5 Technical Committee which developed this document con-
sists of a group of experienced and qualified specialists on
recording of digital information on magnetic tape.
In the development of this standard careful consideration was
given to current practices, existing equipment and 'supplies,
and the broadest possible acceptance while providing a basis
for future improvement in the use of the medium..
This standard was approved as an AN Standard by the American
National Standards Institute on
Suggestions for improvement derived from the use of this stand-
ard will be welcome. They should be sent to the American
National Standards Institute, 1430 Broadway, New York, New
York 10018.
The ANSI Committee on Computers and Information Processing at
the time of approval of this standard had the following member-
ship:
The Technical Committee on Magnetic Tape, X3B5, which developed
this standard, had the following membership:
Proposals developed by an ANSI Technical Committee are the re-
sult of individual effort though the members are variously af-
filiated.
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CLh4TEi4TS
Section Page
1. Scope . . . . . . . . . . . . . . . . . . . . . . . . . 5
2. Definitions and Explanations of Terms . . . . . . . . . 5
2.1 24agnektc Tape-Cartridge . . . . . . . . . 5
2.2 Flux Reversal . . . . 5
2.3 Density . . 5
2.4 Recorded Block . . . 5
2.5 Data Block . . . . . . . . . . . . . . . . . . . 5
2.6 Interb lock Gap . . . . . . . . . . . . . . . . 5
2.7 In Contact . . . . . . . . . . . . . . . . 5
2.8 Control Block (Tape Mark) . . . . . . . . . . . . 5
2.9 Reference Alignment Cartridge . . . . . . . . . . 6
2.10 Preamble . . . . . . . . . . . . . . . . . . . . 6
2.11 Postamble . . . . . . . . . . . . . . . . . . . . 6
2.12 CRC Character . . . . . . . . . . . 6
2.13 Beginning of Tape (t3OT) Marker 6
2.14 End of Tape (EOT) Marker 6
2.15 Load Point (LP) . . . . . . . . . . . . . . . . 6
2.16 Early Warning (EW) . . . . . . . . . . . . . . 6
2.17 Amplitude Reference Tape . .'. . . . . . 6
2.18 Standard Reference Current . . . . . . . . . . . 6
2.19 Standard Reference Amplitude . . .. . . . . . . 6
2.20 Track . . . . . . . . . . . . . . . . . . . . - . . 7
3. Recording . . . . . . . . . . . . . . . . . . . . . . . 7
3.1 Method . . . . . . ? . . . . . . . . . . . . 7
3.1.1 Data .Bit. . . . . . . . . . . . . 7
3.1.2 Data Bit "0" . . . . . . . . . . . . . . 7
3.1.3 Phase Flux Reversals . . . . . . . . . . 7
3.2 Equipment . . . . . . . . . . . . . . . . . . . 7
3.3 Density . . . . . . . . . . . . . . . . . 7
3.3.1 Bit Spacing . . . . . . . . . 7
3.3.2 Long Term Average Sit Spacing . . . . . . 7
3.3.3 Short Term Average Bit Spacing 8
3.4 Flux Reversal Spacing . . . . . . . . . . . . 8
3.4.1 Data Bit to Data Bit Tolerance . . . . . 8
3.4.2 Data Bit to Phase Flux Reversal
Tolerance . . . . . . . . . . . . . . . 8
3.5 Signal Amplitude . . . . . . . . . . . . . . . . 8
3.5.1 Average Signal Amplitude . . . . . . . . 8
3.5.2 Maximum Signal Amplitude . . . . . . . . 8
3.5.3 Minimum Signal Amplitude . . . . . . . . 8-
3.5.4. Azimuth Alignment . . . . . . . . . . . . 8
3.5.5 Rejected Regions . . . . . . . . . . . . 9
3.6 Erase . . . . . . 9
3.6.1 Erase Direction 9
3.6.2 Erase Function . . . . . . . . . . . . 9
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C( )NThtVI, I;
Section
4. Format . . . . . . . . . . . . . . . . . . . . . . . . .
4.1 Number of Tracks . . . . . . . . . . . . . . . . . 9
4.2 Use of Tracks . . . . . . . . . . . . . . . . . .
4.3 Byte anu Code Requirements . . . . . . . . . . . . 9
4.3.1 byte size . . . . . . . . . . . . . . . . 9
4.3.2 t3it sequence . . . . . . . . . . . . . . . 9
4.4 Gaps . . . . . . . . . . . . . . ... . . . . . . 9
4.4.1 Initial Gap . . . . . . . . . . . . . . . 9
4.4.2 Interblock Gap . . . . . . . . . . . . . . 10
4.4.3 Gap Polarity . . . . . . . . . . . . . . . 10
4.4.4 Intregity of Gaps . . . . . . . . . . . . . . . . . i()
4.5 Block Length . . . . . . . . . . . . . . . l')
4.5.1 Minimum Data Block Length . . . . . . . 10
4.5.2 Maximum Data Block Length . . . . . . . . 10
4.5.3 Preamble . . . . . . . . . . . . . . . . . 10
4.5.4 Pos tamb le . . . . . . . . . . . . . . . . 10
4.6 Control Block (Tape Mark) . . . . . . . . . . . . 10
4.7 CRC. Character . . . . . . . . . . . . . . . . . . 10
4.8 Useable Recording Area .. . . . . . . . . . 10
Figures
Fig. 1 Cartridge Diagram
Fig. 2 Tape Guide and'Track Dimensions
Fig. 3 Recorded Block
Fig. 4 Tape Position Holes and Recording Format (Inches)
Fig. 4 Tape Position Holes and Recording Format (Millimeters)
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 DRAFT PROPOSEb
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AMERICAN NATIONAL STANDARD
Recorded Magnetic Tape Cartridge for Information Interchange
4-Track, 0.250 inch (6.30mm), 1600 BPI (63bpmm), Phase Encoded
1. Scope'and Purpose
1.1 Scope
This American National Standard is intended to provide a format
and recording standard for a 0.250 inch (6.30mm) wide, 4-track, magnetic tape
in a cartridge to be used for information interchange between information
processing systems, communication systems, and associated equipment utilizing
the American National Standard Code for Information Interchange, X3.4-1968
(ASCII) and amendments thereto. This standard refers solely to recording on
the 0.250 inch (6.30mm) magnetic tape cartridge and supports ANSI Standards
and complements the American National Standard Unrecorded 0.250 inch (6.30mm)
Wide Magnetic Tape Cartridge for Information Interchange (X3._-19xx in
preparation, presently X3B5/75-43) where the following sections are dealt
with in detail: general requirements, definition, tape and cartridge,
physical and magnetic requirements, speed requirements, and write enable.
feature. Compliance with the unrecorded standard is a requirement for
information interchange.
CAUTION NOTICE: The user's attention is called to the possi-
bility that compliance with this standard may require use of an
invention covered by patent rights.
By publication of this standard, no position is taken with
respect to the validity of this claim or of any patent rights in
connection therewith. The patent holder has, however, filed a
statement of willingness to grant a license tinder these rights
on reasonable and nondiscriminatory terms and conditions to
applicants desiring to obtain such a license. Details may be
obtained from the publisher.
No representation or warranty is made or implied that this
is the only license that may be required to avoid infringement
In the use of this standard.
1.2.1 This standard defines the requirements and supporting test
methods necessary to ensure interchange at acceptable performance levels.
It is distinct from a specification in that it delineates a minimum'of
restrictions consistent with compatibility in interchange transactions.
1.2.2 Wherever feasible, quantitative performance levels which
will be met or exceeded as a result of conformance to this standard are
given. Quantitative limits for some of the requirements falling within
the scope of this standard are not stated but are left to agreement between
interchange parties. Standard test methods and measurement procedures shall
be used to establish such quantities.
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1.2.3 Conversions of toleranced dimensionH from U.S. customary
engineering units (similar to British imperial units) to S1 units have been
done in this standard according to ISO R 370 Method B1. U.S. engineering
units are the original dimensions in this standard.
1.2.4 Except as indicated in 1.2.2 above, interchange parties
conforming to the applicable standards should be able to achieve compati-
bility without need for additional exchange of technical information.
2. Definitions and Explanations of Terms.
For the purpose of this standard, the following definitions apply:
2.1 Magnetic Tape Cartridge. A cartridge containing 0.250 inch
(6.30mm) wide magnetic tape wound on two coplanar hubs with an internal
drive belt to transport the tape between the hubs. (See Figure 1)
2.2 Flux Reversal. The position of a flux reversal is defined as
that point which exhibits the maximum free space flux density normal to
the tape surface.
2.3 Density. The number of data bit flux reversals per unit
length of recorded track, exclusive of phase flux reversals; usually
expressed in bits per inch.
2.4 Recorded Block. A'group of contiguously recorded bits which
extend from one interblock gap to the next interblock gap. This includes
the data bits, CRC, and synchronizing bits, such as preamble and postamble
(See Figure 3.)
2.5 Data Block. A group of contiguously recorded bits, less CRC
and synchronizing bits, such as preambles and postambles, considered and
transported as a unit containing one or more logical records, or portions
of logical records.
2.6 Interblock Gap. A DC erased section of tape separating blocks
of information.
2.7 In Contact. An operating condition in which the oxide side of
a tape is in physical contact with a magnetic head.
2.8 Control Block (Tape Mark). A special control block recorded
on magnetic tape to serve as a separator between files and file labels, or
to define the end of recorded data.
I In the corresponding national standards of ISO member nations, additional
rounding may be done to produce preferred values. These values usually
lie within the original tolerance ranges.
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tape on which continuous information has been recorded. The ref-
crence alignment cartridge has been optimized for perpendicularity
of the written flux transiti.on to the cartridge po::i tion.i.ny plane.
2.10 Preamble. A special sequence of bits recorded at the
beginning of each recorded block.
2.11 Postamble. A special sequence of bits recorded at the
end of each recorded block.
2.12 CRC Character. The CRC is a 16 bit cyclic redundancy
check character that is written after the data and preceding the
postamble of each block for the purpose of error detection.
2.13 Beginning of Tape (BOT) Marker. The BOT marker is a set
of two holes punched in the tape. There are three sets. of holes
provided, the innermost of which is used for the purpose of identi-
fying the storage position for the cartridge. In the storage posi-
tion, all of the permissible recording area is wound on the supply
hub and is protected by at least one layer of tape. Cartridges to
be interchanged shall be rewound to the storage position prior to
interchange. The additional sets of holes are used to insure reli-
ability of detection. (See Figure 4.)
2.14 End of Tape (EOT) Marker. The EOT marker.is a single
hole punched in the tape. There are three such holes along a sin-
gle line. The first to pass the photo sensor during forward oper-
ation indicates that the permissible recording area has been ex-
ceeded. The additional sets of holes are used to insure reliabil-
ity of detection. (See Figure 4.)
2.15 Load Point (LP) Marker. The LP marker is one hole punched
in the tape to indicate the beginning of the permissible recording
area in the forward direction. (See Figure 4.)
2.16 Early Warning (EW) Marker. The EW marker is one hole
punched in the tape between recorded tracks for the purpose of in-
dicating the approaching end of the permissible recording area in
the forward direction. Recording must halt before the EOT marker
is sensed. (See Figure 4.)
2.17 Amplitude Reference Tape. A tape selected for a given
property to establish the reference output signal level when re-
corded with continuous "ones" at 3200 frpi (126 frpmm).
2.18 Standard Reference Current. The minimum write current
which when applied to the amplitude reference tape causes an out-
put signal equal to 95% of the maximum output at 3200 frpi (126
frpmm.)
2.19 Standard Reference Amplitude. The peak-to-peak output
level. which is read from the amplitude reference tape when written
at 3200 frpi (126 .frpmm) with a write current which is 1.5 times
the value of the standard reference current.
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 Hit X3.56 Ap -eld! dt~#Relela 2 YOS D7-t'bIALRDP83T00573R0006d6i-bbeDt41 y kevi:.;( d
for Iniormatlon Interch ai)te ,Tune 9, 1976
Page 7
2.20 `track.. A longitudinal area oil thu tape aluny whi ca, ao
series of magnetic signals may be recorded.
3. Recording.
3.1 Method. The method of recording shall be pilase enc.odi.ny.
Each data bit requires a reversal of flux polarity in a given cal --
rection for a logical "1", and in the opposite direction for a
logical "0". Phase flux reversals will occur at the nominal mid-
point between data bits in order to permit the proper polarity
shift for the following data bit. "Self-clocking" is attained in
this recording method through the consistent occurrence of flux re-
versals for each data bit, 1600 times per inch (63 times per mm).
The erasing process described in Section 3.6 forms part of the re-
cording procedure.
3.1.1 Data bit "1". A "1" data bit is defined as a
flux reversal to the same polarity as the interblock gap when read-
ing in the forward. direction.
3.1.2. Data bit "0". A "0" data bit is cifined as a flux
reversal to the polarity that is opposite to that of the interblock
gap when reading in the forward direction.
3.1.3 Phase Flux Reversals. Flux reversals that occur
at the nominal midpoint between successive "1" bits or between suc-
cessive "0" bits to establish proper polarity for the following
data bit-are called phase flux reversals.
3.2 Equipment. The equipment and cartridge used for inter-
change must satisfy the requirements of Sections 3.3 to 3.6 inclu-
sive. All signal measurements are made at a point in the read
chain where the amplitude is proportional to the rate of change of
the. flux in the read head. For
the purpose of relating bit spacing along the tape to cartridge
driving speed, the ratio of tape speed. to the surface speed of the
belt capstan shall be'assumed to be exactly 0.76.
3.3 Density. The nominal recording density shall ire 1600
bits per inch (63 bpmm) . Density statements in bits per itacn (bits
per nun) are always exclusive of phase flux reversals.
3.3.1 i3it Spacing. The nominal bit' spacing exclusive-
of phase flux reversals is 625 r,Iicroinches (15. gum)
3.3.2 Long Tenn Average hit Spaci nyy . The long term
average bit spacing shall be within ? 3'01 of the nominal spacing.
This a.verage shall be measured over a minimum tape length of 150
inches (3 , 8lm) .
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3.3..3 Short Term Average Lift Spacing. rho short term
average bit spacing referred to a particular bit-spaciiiy is the
average of the preceding four bit-spacinqs.
The short term average bit spacinq, exclusive 01 the effects of
Section 3.4, shall be within ? 7% of the long term average bit
spacing. In addition, the short term average tit spacing shall
not change at a greater rate than 2% per bit.
3.4 Flux Reversal Spacing. To determine the instantaneous
spacing between any two flux transitions, the following two
paragraphs must be taken together:
3.4.1 Data i3it to Data i3it Tolerance. The spacing be-
tween successive data bits without an intervening phase flux re-
versal shall be between 88% and 105% of the short term average
bit spacing.
The spacing between successive data bits with an intervening
phase flux reversal shall be between 95% and 112% of the short
term average bit spacing.
3.4.2 Data bit to Phase Flux Reversal Tolerance. The
spacing between a data bit and any adjacent phase flux reversal
shall be between 44% and 56% of the short term average bit spac-
ing.
3.5 Signal Amplitude. The following apply to writing and
reading in contact.
3.5.1 Average Signal Amplitude. The average peak-to-
peak signal amplitude of the interchange tape at 3200 frpi (126
frpmm) shall deviate no more than +50% -35%, from the standard
reference amplitude. Averaging shall be done over a minimum of
3200 flux reversals, which, for interchange cartridges, may be
segmented into groups.
3.5.2 Maximum Signal Amplitude. The peak-to-peak sig-
nal amplitude at 1600 frpi (63 frpmm) shall be less than three
times the standard reference amplitude.
3.5.3 Minimum Signal Amplitude. No tape when inter-
changed shall contain any adjacent flux reversals whose peak-to-
peak signal amplitude is less than 20% of the standard reference
amplitude.
3.5.4 Azimuth Alignment. wnen adjusted for maximum
output, the read head azimuth angles for a reference alignment
cartridge and for the interchange cartridge shall. not differ by
more than ? 10 minutes.
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3.5.5 Rejected Regions.. A rejected region is an area
of tape extending across the track width and not more than 1.0
inch (25,4mm) :Ln length which exhibits permanent dropouts on
two consecutive passes. The number of rejected regions in an
interchange environment is a matter of agreement between inter-
change parties.
3.6.1 Erase Direction. The tape shall be magnetized
so that the beginning of tape is a North-seeking pole.
3.6.2 Erase Function. Erasure, whether by the write
head or the erase head, shall insure that the level of the read
back signal amplitude is below 3% of the average signal ampli-
tude at 3200 frpi (126 frpmm).
4.1. Number of Tracks. There will be up to four tracks.
Each track is a data track and will be independent of the other
tracks. Individual read/write units may provide one, two, or
four tracks. The number one track must be readable on all units.
The number two track is readable on either two or four track
units (i.e., track positions, track widths, and erased areas must
be compatible between units with a varying number of tracks).
4.2 Use of Tracks. Each track shall be written in serial
fashion starting near the 8OT and continuing toward the EOT, with
a rewind to BOT before initiating writing on the next track. All
tracks are primarily data tracks, however, if one or more tracks
are used for other than data, the number one track must always be
a data track. Track locations and designations are shown in Fig-
ure 2.
4.3 Byte and Code Requirements.
4.3.1 Byte Size. The system shall be capable of read-
ing and writing an 8 bit byte. The American National Standard
Code for Information Interchange 7-bit coded character set (X3.4-
1968) is recorded in the 7 least significant bit-positions of an
eight bit byte. The 3th position is always a zero bit.
4.3.2 Bit Sequence. bits are recorded on the tape in
serial fashion. The low order data bit (bl) is recorded first,
then the next data bit (b2), and so on to the high order data bit
(b8). The data bits of ASCII are numbered b8, b7, b6, b5, b4,
b3, b2, and bl from the high order to low order.
4.4 Gaps.
4.4.1 Initial Gap. The initial gap is the distance
between the load point and the first bit of the first recorded
block on tape. The minimum distance is 6.0 inches (152.4mm).
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9
 Approved For Release 2002/05/17 : CIA-RDP83T00573R000600200003-4
4.4.2 Interblock Gap. For data interchange,.-he length
of the interblock gap shall be a minimum of 1.2 inches (30,5mm),
and a maximum of 48 inches .(1219 mm). Preambles and postambles are
not considered as part of the IBG.
4.4.3 Gap Polarity. The polarity of all gaps shall be
established by the erase function in the direction specified in
Section 3.6.1.
Integrit) ..f Gaps
The gaps shall be DC erased. Immediately before and
after each block there shall be a length of at least
0.09 in (2.3 mm) in which, exclusive of residual
edge signals, there is no flux discontinuity capable
of producing a read signal of more than 107. of half
the Standard Reference Amplitude.
In the remaining part of the gap one: burst of spurious
transitions can bi tolerated, provided tha' the r?tal
number of transitions are 7 or less.
4.5 Block Length.
4.5.1 Minimum Data Block Length. The minimum data
block is that group of bits, exclusive of preamble and postamble,
and CRC, that can be considered a valid block. This minimum
block length, exclusive of the tape mark, is six 8 bit data bytes.
4.5.2 Maximum Data Block Length. The maximum data
block length is 2048 bytes.
4.5.3 Preamble. Preceding the data in each block a
preamble shall be written consisting of 15 zero bits followed by
a one-bit. (See Figure 3.) The preamble may be used to estab-
lish a timing sequence so that data can be react in the forward
direction.
4.5.4 Postamble. Following the data and the CRC char-
acter in each block, a postamble shall be written consisting of
one one-bit followed by 15 zero bits. (See Figure 3.) The post-
amble may be used to establish a timing sequence so that data may
be read in the reverse direction.
4.6 Control Block (Tape Mark). The control block (tape
mark) shall consist of a preamble, two bytes of eight "zero" bits
each, and a postamble.
4.7 CRC Character. A 16 bit CRC shall be written in each
data block following the data and immediately preceding the post-
amble. The CRC is generated by the polynomial X16 + X15 + X2 + 1.
4.8 Useable Recording Area. All data to be interchanged shaill be
written within the useable recording area as defined in Figure 4.
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 Approved For Release 2002/05/17 : CIA-RDP83T00573R000600200003-4
SUPPLY HUB
TAPE SHOWN IN
E.O.T. POSITION
RUBBER COVERED ---
DRIVE ROLLER
DRIVE MOTOR
BELT GUIDE ROLLERS (2)
DIRECTION OF FORWARD
TAPE MOTION
Approved ForFRel e ase E 2b0~70g/~T I:T.Ti~C-F2~ Yt 738000600200003-4 11
 Approved For Release 2002/05/17 : CIA-RDP83T00573R000600200003-4
.004 IN (0.10 mm) MAXIMUM CLEARANCE OF
MINIMUM WIDTH TAPE IN
MAXIMUM WIDTH GUIDE
TRACK 3 -7,;~
TRACK 2:-71,
TRACKI
.070 ?p01 IN (1 .778?0.025 mm)
TRACK DIMENSIONS TO CARTRIDGE REFERENCE
INCHES
MILLIMETERS
TRACK
DIMENS
ION X
DIMENSION Y
DIMENSI
ON X
DIMENSION Y
MAX
MIN
_MAX
MIN
MAX
MIN
MAX
MIN
I
.146
.130
.194
.178
3.71
3.30
4.93
4.52-
2
.210
.194
.258
.242
5.33
4.93
6.55
6.15
3
274
.258
.322
.306
6.96
6.55
8.18
7.77
4
.082
.066 .130
.114
2.08
1.68
3.30
2.90
FIGURE 2. TAPE GUIDE a TRACK DIMENSIONS
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 Approved For Release 2002/05/17 : CIA-RDP83T00573R000600200003-4 ,
IDEAL FLUX PATTER N
GAP
In
L, I
PREAMBLE
1J1
DA TA
0 0 0 0 r 0 G 0 0 0 0 0 t C. I 1 0 1 0 0
CRC POSTAMBLE 41 if -4 --
tj t-i
o- o I o o I o o c o 0 0 0 0 0 0 0 0 o c o
I PREAMBL E J DATA l
8 BIT PYTES
CRC I POSTAMMSLE
16 RATS
TPACK
AREA
ONE"ONE"BIT -FIFTEEN"ZERO0BITS
-FIFTEEN" ZERO" BITS - ONE" ONE" BIT
FIGURE 3. RECORDED BLOCK
GAP
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JJUTh
 Approved For Release 2002/05/17 : CIA-RDP83T00573R000600200003-4
,023!0.002 DIA?
2 HOLES USEABLE
-RECORDING ?---;-
I. \ AREA
-TRACK 3/1//////
-TRACK 21111illllll~/If117/
-TRACK IIIIIIIIIIIbIIII/I
-TRACK 4/f//I//I/I I//I//I
0.187 '?-O.002
?
?
?3
3
18 18 -~--18 --~--
PHYSICAL' E.O.T.--~
END OF HOLES
TAPE
48 ;3
+10
-300 FEET
-0
EARLY
WARNING
LOAD
POINT
6 MIN.
36
+3
:JE 0.005
3 PLACES
"FORWARD" D-RECTION
OF TAPE TRAVEL (OXIDE
SIDE OF TAPE SHOWN)
+ 0.w Co.
-oixm
0.247000Q
18 +-f+18 +14 18+-.
~--- B.O.T.--J
HOLES
PHYSICAL
BEGINNING
OF TAPE
TOLERANCE AS NOTED
DIMENSIONS IN INCHES
FIGURE 4 TAPE POSITION HOLES a RECORDING FORMAT
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 FIPS PUB
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Federal Information
Processing Standards Publication
Announcing the Standard for
MAGNETIC TAPE CASSETTE FOR INFORMATION INTERCHANGE
(CO-PLANAR, 3.81 mm (0.150 in), 32 bpmm (800 bpi), PE)
Federal Information Processing Standards Publications are issued by the
National Bureau of Standards pursuant to the Federal Property and Adminis-
trative Services Act of 1949 as amended, Public Law 89-306 (79 Stat. 1127),
Executive Order 11717 (38 FR 12315), dated May 11, 1973), and Part 6 of
Title 15 CFR (Code of Federal Regulations).
Name of Standard. Magnetic Tape Cassette for Information Interchange (Co-
Planar, mm (0.150 in), 32 bpmm (800 bpi), PE) (FIPS PUB ).
Category of Standard. Hardware Standard, Interchange codes and media.
Explanation. This standard specifies the physical, magnetic, and recorded
characteristics of a 3.81 mm (0.150 in) magnetic tape cassette in order to
provide for data interchange between information processing systems at a
recording density of 32 bits per millimeter (800 bits per inch) using phase
encoding techniques. The magnetic tape cassette consists of a twin hub co-
planar type cassette containing 3.81 mm (0.150 in) wide magnetic tape. This
standard is one of a series of Federal Standards implementing the Federal
Standard Code for Information Interchange (FIPS 1) on magnetic tape media.
Approving Authority. Secretary of Commerce.
Maintenance Agency. Department of Commerce, National Bureau of Standards
nsti u e for Computer Sciences and Technology).
Cross Index.
a. American National Standard X3.48-1976, Magnetic Tape Cassette for
Information Interchange (Co-Planar, 3.81 mm (0.150 in), 32 bpmm (800 bpi), PE).
b. FIPS PUB 1, Federal Standard Code for Information Interchange.
c. FIPS PUB 35, Code Extension Techniques in 7 or 8 Bits.
d. At the time of publication of this FIPS PUB, a standard for dual
track complementary return-to-bias four state recording (CRB) for a 3.81 mm
(0.150 in) magnetic tape cassette was being developed by the American National
Standards Institute. This voluntary industry standard, when available, will
be considered for Federal adoption as a FIPS.
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 Approved For Release 2002/05/17 : CIA-RDP83T00573R000600200003-4
Applicability. This standard is applicable to the acquisition and use to
all magnetic tape cassette recording and reproducing equipments employing
3.81 millimeter (0.1150 inch) wide magnetic tape at recording densities of
32 bits per millimeter (800 bits per inch) using phase encoding. Federal
information processing systems employing such equipment, including associated
software, shall provide the capability to accept and generate recorded
magnetic tape cassettes in compliance with the requirements set forth in
this standard.
Specifications. This standard adopts the requirements set forth in the
American National Standard X3.48-1976, Magnetic Tape Cassette for Information
Interchange (Co-Planar, 3.81 mm (0.150 in), 32 bpmm (800 bpi), PE).
Implementation Schedule. All applicable equipment ordered on or after the
date of this FIPS PUB must be in conformance with this standard unless a
waiver has been obtained in accordance with the procedure described below.
Federal departments and agencies are responsible for issuing specific
internal implementation instructions for the use by this standard by their
organizational units; and for assuring that copies of this FIPS PUB and its
associated technical specification (American National Standard X3.48-1976)
are made available to all effected parties.
Special Information. Federal standards and/or specifications for unrecorded
magnetic tape cassettes will be developed and issued by the General Services
Administration. Until such time as these are available, American National
Standard X3.48-1976, Magnetic Tape Cassette for Information Interchange
(Co-Planar, 3.81 mm (0.150 in), 32 bpmm (800 bpi), PE), should be cited in
Federal procurements.
Also, GSA will provide terminology for use of this standard in Federal ADP
acquisitions. This terminology will be incorporated in the Federal Property
Management Regulations (Title 41, Subtitle C, Part 101, Subpart 101-32.13,
Code of Federal Regulations).
Qualifications. None.
Waiver Procedures. (The approval and processing of waivers to Federal
Information Processing Standards is currently being reviewed by the Department
of Commerce and will be provided in the printed version of this FIPS PUB.)
Where to Obtain Copies of the Specifications.
(To be completed by NBS.)
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 Approved For Release 2002/05/17 : CIA-RDP83T00573R00060020000?St X3.48
(Revision,of X3B5/75-03
and X3/75-05)
X3B5/75-55
1975 Oct 1
Project 213
Seventh Draft
Proposed
American National Standard
Magnetic Tape Cassette for Information Interchange
(Co-Planar, 3.81 mm [0.150 in],
32 bpmm [800 CPI], PE)
This 7th Draft is the result of X3B5 actions to
more closely align the domestic proposal with the
corresponding international proposal, ISO/DIS 3407.
Changes from the 6th Draft, which had earlier been
approved by X3, are noted by marginal rulings.
X3 members are given 30 days in which to register
objections to these changes. If no objections are
received, this draft will be submitted to ANSI.for
final approval. Objections should be submitted
not later than 1976 February 10, addressed to:
CBEMA/Secretary X3
1828 "L" ST NW
Washington DC 20036
Prepared by
Technical Committee X3B5 - Magnetic Tape Cassettes
American National Standards Committee
X3 - Computers and Information Processing
Secretariat: Computer and Business Equipment Manufacturers Association
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 Approved For Release 2002/05/17 : CIA-RDP83T00573R000600200003-4
FORE,:O^O
(This Foreword is not a part of American National Standard Magnetic Tape
'Cassettes for Information Interchange, X3.48-197 )
This standard presents the minimum requirements for ir:echanical
and magnetic interchangeability of 0.150 Inch wide magnetic tape and the
associated tape cassette between information processing systc;s, c:riuni-
cation systems and associated equipment using the ASCII X3.4-19 3 and Amendments
thereto on magnetic tape at 32 bits per mm. (800 bpi) using phase encoding
techniques.
Subsequent standards may specify higher densities. other
cassettes with wider and thicker tapes, will define ^crt fully t~e
physical magnetic tape and will specify a standard record format and
labels. Other recording formats may also be specified.
The X385 Task Group which developed this document consists of
x.group of experienced and qualified specialists on recording of digital
information on magnetic tape.
In the development of this standard, careful consideration was
given to current practices, existing equipment and supplies, and the
broadest possible acceptance while providing a.basis for future improvement
in the use of the medium.
This standard was approved as an American National Standard by the
American National Standards Institute on
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 Approved For Release 2002/05/17 : CIA-RDP83T00573R000600200003-4
Suggestions for improvement derived from use of this
Standard will be welcome. They should be sent to the A;,,-zricdn
National Standards Institute; Inc., 1430 Broadway, New York 10018.
At the time the proposal was developed and processed
through the X3 Committee (Computers and Information Processing),
the membership was :
The Task Group on Magnetic Tape, X3B5 which developed this
standard had the following personnel:
Proposals developed by an ANSI Subcortyittee or Task Group
are the result of individual effort, though the members are variously
affiliated.
-ii-
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 Approved For Release 2002/05/17 : CIA-RDP83T00573R000600200003-4
TABLE OF CONTENTS
1. Scope
2. Definitions and Explanation of Terms
3. Environment and Transportation
3. 1 Testing Environment
3. 2 Operating Environment
3.3 Transportation and Storage Environment
3.4 Transportation
4. Characteristics of Tape
4.1 Mechanical Properties
4.2 Tests of Magnetic Properties
4.3 Electrical Surface Resistance
5. Tape Cassette
5.1 Identification of Cassette Sides
5.2 Mechanical Characteristics
5.3 Basic Specifications
5.4 Labelling of Tape Cassettes
6. Recording
6. 1 Method of Recording
6.2 Equipment
6.3 Density of Recording
6.4 Flux Reversal Spacing
6.5 Signal Amplitude
6.6 Number of Elongated Gaps
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 Approved For Release 2002/05/17 : CIA-RDP83T00573R000600200003-4
TABLE OF CONTENTS (cont'd)
6.
(cont'd)
6. 7 Alignment Error
6.8 Tape Winding Torque
6.9 Residuals of Previous Recordings
7.
Format
7. 1 Number of Tracks
7.2 Track Dimensions
7. 3 Track Designation
7.4 Use of Tracks
7.5 Location of Characters on the Tracks
7.6 Sequence of Recording
7. 7 Code
7.8 Sequence of Characters
7.9 Data Block
7. 10 Control Block
7.11 Gaps
7.12 Preamble and Postamble
7. 13 Cyclic Redundancy Check (CRC)
-iv-
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 Approved For Release 2002/05/17 : CIA-RDP83T00573R000600200003-4
TABLE OF CONTENTS (cont'd)
FIGURES
Figure 1 Sides, Tracks, Holes and Asymmetrical Slot
Figure 2 Position of Heads
Figure 3 Tape Guides in Cassette
Figure 4 Cassette Dimensions
Figure 5 Cassette Support Planes
Figure 6 Maximum Label and Window Area Dimensions
Figure 7 Usable :Recording Area
Figure 8 Recording Format 800 BPI
APPENDICES
Appendix A Possible Test for Layer-to-Layer Adhesion
Appendix B Measurement of Light Transmittance
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 Approved For Release 2002/05/17 : CIA-RDP83T00573R000600200003-4
1. Scope
1.1 To seta standard for a 3.81mm (0. 150 in) magnetic tape
cassette to provide data interchange and physical interchange-
ability between information processing systems utilizing the American
National Standard Code for Information Interchange (ASCII
X3.4-1968) and amendments thereto. The cassette is of
the twin hub co-planar type, loaded with a 3.81mm (0. 150 in)
wide magnetic tape for digital recording using the 31.5 bits
per mm (800 bpi) phase encoding method. The direction of
magnetization is in the longitudinal direction of the tape.
NOTE: Throughout the remainder of the standard for the
sake of simplicity, the recording density is stated
as 32 bpmm, (800 bpi) nominal.
1.2 The Standard applies to cassettes and data used for inter-
change. Where it applies for testing only, this is specifically
stated.
2. Definitions and Explanation of Terms
For the purpose of this Standard, the following definitions apply:
2.1 Magnetic Taoe
A tape which accepts and retains magnetic signals intended for
Input/output and storage purposes of information processing
and associated systems.
2.2 Reference Tape Cassette
A tape cassette arbitrarily selected for a given property for
calibrating purposes.
2.3 Secondary Reference Tape Cassette
A tape cassette intended for routine calibrating purposes,
the performance of which is known and stated in relation to
that of the Reference Tape Cassette.
(Former section 2.4 deleted)
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 Approved For Release 2002/05/17 : CIA-RDP83T00573R000600200003-4
2.4 Reference Field
The minimum 'field which, when applied to the Reference
Recording Field Tape Cassette, causes a signal output
equal to 95% of the maximum signal output at the specified
test packing density (see 4.2).
2.5
Test Recording Current
A recording current between 145% and 155% of the current
required to produce., the Reference Field.
2.6 Signal -m litude Reference Tape Cassette
A reference tape cassette selected as a standard for signal
amplitude.
NOTE: A Master Standard (Computer Amplitude)
has been established at the U.S. National
Bureau of Standards based on reference tape
cassettes and heads as the result of work
by national standardization organizations and
national laboratories coordinated by the U.S.
National Bureau of Standards. Secondary
signal amplitude reference tape cassettes
are available from NBS under part number;
SRMM 1600.
2.7 Standard Reference Amplitude
2.8
The Standard Reference Amplitude is the average peak-to-peak
signal amplitude derived from the Signal Amplitude Reference
Tape Cassette, at the density of 63 ftpmm (1600 ftpi) using
the Test Recording Current (see 2.5). The signal
amplitude shall, be averaged over 4000 flux transitions.
Ave rage Signal Amplitude
The average peak-to-peak value of the signal output measured
over at least 4000 flux transitions.
2.9 In Contact
An operating condition in which the magnetic surface of a tape
is in physical contact with a magnetic head.
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 2.10 Track
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A longitudinal area of the tape along which a series of magnetic
signals may be recorded.
2.11 Bit Density
The number of bit flux transitions per unit length of track.
2.12 Position of Flux Transitions
The position of a flux transition is defined as that which
exhibits the maximum free space flux density normal to the
tape surface.
2.13 Leader
Non-magnetic transparent tapes joined to each end of the
magnetic tape, for reasons of strength and convenience.
2.14 Erasing Field
A unidirectigpal field of sufficient strength to remove th;2
signals from the tape.
Print Through
Any unwanted signals induced in one layer of tape by the
field of a deliberately recorded signal in an adjacent layer
or layers.
2.16 Reference Alignment Cassette
A cassette containing tape on which continuous information
has been recorded, where the optimum playback head gap
alignment does not differ by more than +3' from the vertical
on the cassette support plane. (Currently these cassettes
are available with wavelengths of 7. Spm [ 295 microinch] and
4. 75um [187 microinch]).
2.17 Typical Field
2.18
The minimum field characteristic of each tape, which, when
applied to the tape under test, causes a signal output equal
to 95% of the maximum signal output at the specified test
packing density.
Tape Cassette Center Line
In Figures 1 through,6, the center line of the cassette is defined as a
line perpendicular to the Prime Reference Line and located midway between
the centers of the two Reference Holes (Figure 4).
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 Approved For Release 2002/05/17 : CIA-RDP83T00573R000600200003-4
3. Environment and Transportation
3. 1 Testing Environment
Tests and measurements made on the cassette to check the
requirements of this Standard shall be carried out under the
following conditions:
Temperature.
RH:
Conditioning before
testing:
23 + Z?C (73 + 5?F)
40%% to 60%
24 hours minimum
3. 2 Operatin Environment
Cassettes used for data interchange shall be operated under
the following conditions:
Temperature:
10?C
to 45?C
(50?F to
113?F)
RH:
20%
to 80%
Wet bulb temperature:
Less
than 26?C (79?F)
The temperature is to be measured in the air immediately
surrounding the cassette. Rapid temperature variations should
be avoided. There shall be no deposit of moisture on or in
the cassette.
3. 3 Transportation and Storage Environment
During transportation and storage, it is recommended that
recorded cassettes are kept within the following conditions:
Temperature: 4?C to 500C (40?F to 122?F)
RH.: 20% to 80%
NOTE: Cassettes which have been exposed to temperatures
exceeding the storage temperature range may exhibit
degraded performance characteristics. Such
cassettes should be subjected to a conditioning period
of not less than 24 hours within the operating
environment prior to use.
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 Approved For Release 2002/05/17 : CIA-RDP83T00573R000600200003-4
3.4 Transportation
Responsibility for ensuring that adequate precautions are
taken during shipment shall be with the sender. During trans-
port, the reels of tapes shall be blocked to prevent any
tendency to unwind. For transport, a rigid container free
from dust or extraneous matter shall be used. The final
package must have a clean interior and construction, preventing
ingress of dust and water. It is recommended that a space
of not less than 80mm (3. 15 in.) exist between cassette and
outer surface of the final container so that risk of damage due
to stray magnetic fields will be negligible.
4. Characteristics of Tape
The tape shall consist of a base material (e. g. oriented polyethylene
terephthalate film or equivalent) coated on one side with a strong
and flexible layer of ferromagnetic material dispersed in a suitable
binder. The magnetic tape shall be continuous and splice-free.
Tape or cassette components which will ignite from a match flame
and when so ignited will continue to burn in a still carbon dioxide
atmosphere shall not be used. Tape or cassette components which
may cause bodily harm by contact, inhalation or ingestion during
normal use of the cassette shall not be used.
4.1 Mechanical Properties
4.1. 1 Tape and Leader Width and Tolerance
The width of tape and leader shall be:
+0 +0
3.81 -0. 05 mm (0.150 -0.002 in. )
4. 1. 2 Tape and Leader Length - -
4. 1.2.1 Tape Length - -
The length of the splice-free tape shall be:
+4
I71
86 -o
13
(282 -0 ft)
4. 1.2.2 Leader Length --
The length of the leader tape shall be such
that the distance from the cassette face to the
beginning of the magnetic tape is 500 +50mm
(19.68 +2. 00in) when the leader tape is pulled
out of the cassette through the opening nearest
to the empty reel.
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4.1.3 Tape and Leader Thickness --
4. i. 3. 1 Thickness of Tape The overall thickness of tape and coating shall
be maximum 19pm (750 microinch) minimum
15pun (600 microinch) with a coating thickness
*f Gum (240 microinch) maximum.
4.11.3.2 Thickness of Leader --
The thickness of the leader shall be 38pm
(1500 microinch) maximum.
4.1.4 Markers -?-
4.1.4.1 The magnetic tape shall be provided with a
beginning-of-tape and an end-of-tape marker
(HOT and EOT).
4. 1. 4. 2 Dimensions --
The markers shall be circular holes having a
diameter of 0. 60 + 0. 05mm (0. 0237 + 0.0020in).
4.3.4.3 Position --
The distance of the marker centers from the
physical beginning and end of the magnetic
tape (for BOT and EOT respectively) shall
be 450 + 30mm (17.7 + 1. 2 in). The distance
between tape centerline and marker centerline
shall be less than 0. 1mm (0. 0039 in).
4.1.5 Light Transmittance --
4.1.5.1 Light transmittance of-tape --
The tape and the backing tape shall each have
a light transmittance of less than 1% measured
according to Appendix B.
4.1.5.2 Light transmittance of leader --
The leader tape shall transmit 75% or more
light, measured .'tccordinr Lo Appendix B.
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4. 1.6 Elastoplastic properties --
4. 1.6. 1 The elastic properties of the tape shall be
such that when subjected to a tension of
0. 5 N (0. 112 lb) for a period of three
minutes under any combination of temperature
and relative humidity within the ranges of
3. 1, the elongation shall be between
0.08 and 0.50%.
4. 1.6.2 The elastoplastic properties of the tape shall
be such that when subjected to a tension of
3 N (0.67 lb) for a period of three minutes
under temperature and humidity conditions
as mentioned in 3. 1, the (permanent)
elongation measured with negligible tension
after a second three minutes interval shall
be less than 1.0%.
4. 1.6.3 The elastic properties of the tape shall be
such that its tensile yield force - defined
as the force required to elongate a sample by 3%
shall be at least 4. 5 N (1.01 lb).
Procedure: Use a static we ighing- constant
rate of grip separation tester capable of
indicating the load to an accuracy of +2%.
Clamp a specimen of tape at least 180mm
(7 in) in length with an initial 100mm (4 in)
separation between jaws. Elongate the
specimen at a rate of 50mm (2 in) per minute
until minimum elongation of 10% is reached.
The force required to produce an elongation
of 3% is the tensile yield force.
4. 1.6.4 The elastic properties of the leader shall be
such that when subjected to a tension of 1.0 N
(0.225 lb) for a period of three minutes under
temperature and humidity conditions as
mentioned in 3. 1, the elongation shall
be between 0.08 and 0.50%.
4.1.7 Longitudinal Curvature --
There shall be a minimum radius of curvature for
the edge of the tape, defined and tested by allowing
a lm (39 in) length of tape to unroll and assume its
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 Approved For Release 2002/05/17 : CIA-RDP83T00573R000600200003-4
natural curvature on a flat surface. The minimum
radius shall be 33m (108 feet) which, if measured
over an arc of a circle, corresponds to a deviation
of 3.8 mm from a I m chord (0.15 in from a 39 in
chord).
4.1.8 Tape-to-Leader Connection --
4.1.8.1 Dimensions --
if a splicing tape is used, this shall not
extend more than 18mm (0.71 in) from
the gap between leader and tape. The
actual gap itself shall be 0.5mi-n (0.02 in)
maximum. An overlap of 0.05mm (0.002 in) maximum
is allowed.
The thickness of the splicing tape shall be
50pm (0.002 in) maximum.
4.1.8.2 Tape-to-Leader Alignment --
.At the area of the splice, there shall be
no lateral discontinuity greater thanl00pm (0.004 in).
The total width of magnetic tape-leader-splicing tape
junction shall be no more than 3.86 mm (0.152 in).
4.1.8.1 Strength - -
After being subjected to a longitudinal static
force of 2N (0.45 lb) for' 44 hours under
the conditions of 3.2, the connection
shall meet the requirements of 4.1.8.1.
4.1.9 Layer-to-Layer Adhesion --
Layer-to-layer adhesion must be sufficiently low to
meet the test of Appendix A.
4.2 Tests of Macnetic Properties
The magnetic properties of- the tape are defined by the testing
requirements given in this section.
4.2.1 Test Density --
Tape shall be tested at 63 ftpmm (1600 ftpi)
nominal.
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 Approved For Release 2002/05/17 : CIA-RDP83T00573R000600200003-4
4. 2. 2
Typical Field --
4.2.3
The typical field of the tape under test shall be
within +20% of the reference field.
Average Signal Amplitude --
When a tape has been recorded with the Test
Recording Current, then played back on a system
which has been calibrated by means of a Signal
Amplitude Reference Tape Cassette recorded under
the same conditions, the Average Signal Amplitude
of the tape under test shall be within +Z5%
- 10%
of the Standard Reference Amplitudt?. When
performing this test, the output signal shall be
measured for the same relative pass for both tapes,
i.e. , read-while-write or read- on-first- pass -after -write.
When a tape has been recorded with the Test Recording
Current, and then passed through a longitudinal steady
erasure field of 79500 A per m (1000 oersteds) the
Average Signal Amplitude of the remaining unwanted
signal shall not exceed 3% of the Standard Reference
Amplitude. The erasure field shall be reasonably
uniform; e. g. , the field in the middle of a solenoid.
This measurement shall be made with a band pass
filter passing at least the first three harmonics.
4. 2, 5 Test for Drop-Outs and Drop-Ins --
These tests shall be carried out in the in-contact
condition and over the entire usable recording area (see
Fig. 7) which shall, in length, extend from 350mm (13.8 in)
before the BOT-marker to 350mm (13. 8 in) beyond
the FOT-marker, and in width over the track widths
as defined in 7. 2.
When performing these tests, the output signal shall
be measured on the same relative pass for both the
Signal Amplitude Reference Tape Cassette and the tape
under test; Le, , read-while-write or read-on-first-
pass-after-write.
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 Approved For Release 2002/05/17 : CIA-RDP83T00573R000600200003-4
4.2.5.1 Drop-Outs --
When a tape has been recorded with the
Test Recording Current, any playback
signal, when measured base-to-peak, which
is less than 50% of half the Standard Reference
Amplitude is a drop-out.
4.2.5.2 Drop-Ins --
When a tape has been recorded with a
constant recording current equivalent to the
Test Recording Current, any playback signal,
when measured base-to-peak, which exceeds
10% of half the Standard Reference Amplitude,
is a drop- in.
4.2.6 Rejected Regions --
A rejected region is an area of tape extending across
the width of either tracks and not more than 10mm
(0.4 in) in length, which, on two consecutive tests,
exhibits drop-outs or drop-ins. (See 6. 6). The
acceptable number of rejected regions in an interchange
environment is a matter of agreement between interchange
parties.
4. 2. 7 Print-Through --
A, tape for testing shall be written with a suitable
pattern using the test recording current, rewound and
stored for a minimum of 16 hours at 60?C (140?F).
At the end of this period the measured print-through
signal shall not exceed 2% of the Standard Reference
Amplitude. As the decay of the print-through signal
on a section of tape is extremely rapid after it has
been removed from the coil, the time elapsing between
the tape leaving the coil and it passing over the test
read head shall not exceed 500ms.
4.3 Electrical Surface Resistance
The surface resistance of the tape shall not exceed-
10 9 ohms/square
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 Approved For Release 2002/05/17 : CIA-RDP83T00573R000600200003-4
NOTE: Resistance per square -- the surface resistance of
a square area of any size, measured between
electrodes placed on two opposite sides of the square.
The unit of the measurement is the ohm.
5. Tape Cassette
5. 1 Identification of Cassette Sides
5. 1. 1 The cassette has its two sides distinguished and
labelled ' A" and "B", respc ctivcly, corresponding to
tracks No. 1 and No. 2 (see Figure 1).
5. 1. 2 The back surface is provided with two holes whose
minimum area, depth and section are indicated in
Figure 1. Writing on a track is enabled by closing
the outer surface of the corresponding hole. When a
closing device other than a plug is used, it must remain
attached to the cassette.
5. 1. 3 The back surface is provided with one slot slightly
off-center (see Figure 1). This slot makes it
possible to distinguish between the sides ''A'' and
"B", both visually and mechanically.
5. 2 Mechanical Characteristics
The mechanical characteristics which define the co-planar
tape cassette and which permit physical interchangeability
of cassettes on any recorder for data interchange of different
manufacture are specified in Figures 1-6. Symmetry about the Tape Cassette
Center Line is re uired (except for the Asymmetrical Slot) with half of the
5.3 Basic Specifications stated tolerances permitted on each side of the
Tape Cassette Center Line.
Furthermore, the following basic specifications apply:
5.3.1 Tape Path and Guidance --
Requirements are shown in Figures 2 and 3.
5. 3. 2 Cassette Support Planes --
The cassette shall be supported by the write/read
instrument only where the total cassette thickness
is obligatory, i. e. , the hatched areas in Figure 5.
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 Approved For Release 2002/05/17 : CIA-RDP83T00573R000600200003-4
5. 3. 3 Holes in Back Surface -
The position and dimensions of the holes in the back
surface are given in Figure 1. The dimensions of the
write-enable device, if used, shall be compatible
with the hole( dimensions as shown. in Figure 1 and
must be such that it may be installed and removed
with reasonable effort and remain seated during normal
use. The write-enable device must not protrude beyond
the back surface and it must not be recessed more than
lmni (0.039 in). The write-enable device shall at
least close the cross hatched area as shown in Figure 1.
5. 3.4 Window Area --
The maximum window area shall be in accordance with
the dimensions given in Figure 6. The maximum
allowable increase in cassette thickness (required, for
example, to accommodate marks indicating amount of
wound and unwound tape) is given for each support
plane.
The minimum withdrawal force of the leader tape from
the hub attachment shall be a static load of 1ON
(?..25 lb) for a period of 10 minutes.
5.3.6 Tape Winding --
The tape shall be wound on the hubs with the magnetic
coating out in such a way that, when recording on
Track No. 1, and looking at label A, the tape is
unwound in an anticlockwise direction.
5. 3. 7 Friction Torque of the Full Hub --
The maximum friction torque of the full hub in the
cassette shall be 2mN?m (0. 28 oz in).
5. 3.8 Friction Torque of Both Hubs -
The maximum friction torque of both hubs measured
in the cassette itself at the nearly full hub shall be
2?7mN?m .(0. 38 oz in). With a holdback torque of
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 Approved For Release 2002/05/17 : CIA-RDP83T00573R000600200003-4
0.8. mN-m (0. 11 oz in) applied to the nearly empty
hub, the required maximum torque to be applied to
the nearly full hub shall not exceed 5.5 mN?m (0. 78 oz in).
5. 3. 9 Pressure Pad - -
The cassette shall be provided with a pressure pad
to hold the magnetic tape against the write/read head.
The pressure of the pad upon the head shall be
5 to 15 kPa (11.6 to 34.8 oz/ in2), when
the minimum distance between head and reference line
lies between 3. lmm (0. 122 in) and 3.8mm (0. 150 in).
This pressure shall be measured on a symmetrically
positioned circular cylindrical surface having a radius
between 10mm (0. 39 in) and infinity (see Figure 2).
Under the above conditions and with 0.8 mN?m
(0. 11 oz in) holdback torque applied to the nearly
empty hub, the required maximum torque applied to
the nearly full hub shall not exceed 16 M -Ii
(2. 25 oz in) to start tape motion, and shall not exceed
12.5 mN.*m (1.78 oz in) to continue tape motion.
Measured from the centerline of the cassette, the
pressure pad shall extend on both sides of this
centerline in the direction of tape travel a minimum
of 2. 5mm (0. 098 in) and a maximum of 4mm (0. 157 in)
Up to the distance of 2. 5mm (0. 098 in) the pressure
requirements still apply. The pressure pad shall be
symmetrically positioned, and the distances between
pressure pad and cassette support planes surrounding
the reference holes shall not exceed 3. 5mm (0. 138 in).
Those values shall also be valid in actual working
conditions.
No magnetic material may be used for the cassette
construction near the position of the write/read head.
No screening shield may be used and the pressure pad
and its holder must be of non-magnetic material.
5. 3. 10 Tape Guides --
The tape touches the cassette at points on either side
of the tape head recesses (indicated by arrows U and L).
(See Figure 3)
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 Approved For Release 2002/05/17 : CIA-RDP83T00573R000600200003-4
Guides are required at these positions. Between
the outer guides (P and S) there must be a closed
construction so as to prevent dust entering the
cassette.
The guides indicated by the letter L shall be per.-
pendicular to the lower support plane (see 5.3.2).
The guides indicated by the letter U shall be per-
pendicular to the upper support plane.
5. 3. 11 Transverse Tolerances of Tape Position --
5.3.11.1 Transverse Tolerances without Tape Tension The extreme position of the tape in the head region
when no tape tension is present shall be limited
by means incorporated in the cassette. The
distance between cassette support planes
surrounding the reference holes and those
means shall lie between 3. Smm (0.138 in)
and 3.7mm (0.146 in).
5.3.11.2 Transverse Tolerances with Tape Tension If the tape is not influenced or touched by
any external means (guides, heads, capstans),
during wind or rewind, the tape edges shall
have a distance of 4. 1 }0.2mm (0. 161 +0.008 in)
from the support plane surrounding the
reference holes (see Figures 4
and
5).
When
track No. 1 is being used, the
side
B
outer
cassette surface is the reference plane.
Conversely, when Track No. 2 is being used,
the side A outer cassette surface is the
reference plane.
5.4 Labelling of Tape Cassette
5.4. 1 Label Area --
The maximum label area shall be in accordance with
the dimensions given in Figure 6. The maximum
allowable depression in the thickness of the cassette
in the label area is given for each support plane.
5.4.2 Interchange --
Suitable labels sh b f,,~.
Approve.c ~$e fteeleaseA002u0 of pI S 83T erasable A0 620600e Sf
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 Approved For Release 2002/05/17 : CIA-RDP83T00573R000600200003-4
not allowed. Position and size of labels used
shall be 1^ss than the provided depre:,sion of the
label at , a.
5.4. 3 ldentifikcr~tion --
The label shall have provisions for the identification
of owner, manufacturer, cassette side and interchange
label. The label sha11 indicate?
a. that the cassette is meant for data interchange
(see 1, Scope);
b. the use of track 2 (see 7. 4);'
c. whether 7 or 8 bit coding is used (see 7. 7);
d. the method of recording.
5.5 Magnetic Properties of the Cassette Housing
The magnetic properties of the cassette housing shall not
impede bulk erasure of the tape by an external device.
6. Recording
6.1 Method of Recording
The method of recording shall be phase encoding, described
as follows:
6.1.1 The tape before the first block, the interblock gaps
and that part of the tape following the last block
written, shall be erased with the same polarity.
This polarity is such that the beginning of the relevant
track is a North seeking pole.
This erasing process forms part of the recording
procedure.
6.1.2 A ZERO bit is defined as a flux transition to the
polarity opposite to that of the interblock bap, when
reading in the forward direction.
6.1.3 A ONE bit is defined as a flux transition to the
polarity of the interblock gap, when reading in the
forward direction.
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 Approved For Release 2002/05/17 : CIA-RDP83T00573R000600200003-4
6. 1.4 Additional flux transitions shall be recorded at the
nominal midpoints between bit flux transitions as
defined in 6. 1. 2 and 6. 1. 3 if required, to
establish the proper polarity for the succeeding bits.
These flux transitions shall be called phase flux
transitions.
6. 2 Equipment
The equipment and tape used for interchange must satisfy the
requirements of 6.3 to 6.8 inclusive.
All signal measurements are made at a point in the read chain
where the amplitude is proportional to the rate of change of
flux in the read head.
6. 3 Densit of Recording
6. 3. 1 The density of recording is 32 bpmm (800 bpi) nominal.
6.3.2 The long term average bit spacing is the spacing
between bit flux transitions that have been recorded
continuously at a nominal density of 32 ftpmm (800 ftpi)
and must be measured over a length of tape of not less
than 3. 81m (12.5 ft).
The long term average bit spacing shall be within +4%
of the nominal spacing of 31. 75pm (1250 microinch).
6.3.3 The short term average bit spacing referred to a particular
bit spacing is the average of the preceding four bit
spacings.
The short term average bit spacing shall be within the
limits of +5% of the long term average bit spacing.
In addition, the short term average bit spacing shall
not change at a rate greater than 2% per bit.
6.4 l:lux Transition Spacing
6.4.1 The spacing between successive data bit flux transitions
shall not differ by more than 10% from the preceding
bit spacing.
6.4.2 The spacing between a phase flux transition and the
preceding data bit flux transition shall be between
45"l, and 55%, of the prec:cding bit spacing.
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6.5. 1. 1 The average peak-to-peak signal amplitude
of the interchanged tape cassette at 63 ftpmm
(1600 ftpi) shall not deviate by, more than
4 50? ", -35% from the Standard Reference
Amplitude. Averaging shall be done over a
minimum of 4000 flux transitions, which,
for the interchange cassette, may be segmented
into blocks.
Signal Amplitude
Average Signal Amplitude --
6.5. 1.2 The average peak-to-peak signal amplitude at
32 ftpmni (800 ftpi) nominal shall be less
than 2 times the Standard Reference Amplitude.
6.5. 1. 3 Averaging shall be done on the first- read- pass-
after- inter change.
No tape cassettes intended for interchange shall contain
any adjacent flux transitions whose base-to-peak signal
amplitude is less than 35% of half of the Standard
Reference Amplitude. This check is to be made during
Read-while-write or Read-on-first-pass-after-write.
6.6 Number of Elongated Gaps
The number of gaps which have been elongated (see 7. 11.4)
due to erase instructions is a matter of agreement between
interchange parties, but it is recommended that this number
not exceed 2, or alternatively 1% of the total number of
blocks written, whichever figure is larger.
Minimum Signal Amplitude --
6.7 Alignment Error
When adjusted for maximum output, the azimuth angles for a
Reference Alignment Cassette, and the information to be in-
terchanged, shall not differ by more than +15'.
6.8 Tape Winding Torque
The take-up torque shall be at least 3mN ?m (0.43 oz -in).
The maximum continuous value of the take-up tape tension shall
be constant or decrease with increasing reel diameter and shall
not exceed 0. 5 N (1.81 oz). The above values apply during
winding, re-winding, recording and playback.
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 Approved For Release 2002/05/17 : CIA-RDP83T00573R000600200003-4
6.9 Residuals of Previous Recordings
In the zone of the tape in which the outer edges of the tracks
are allowed to vary (see 7.2.2), there can be residuals of
previous recordings.
7.
Format
7.
1
Number of ;,racks
There shall be two tracks (see Figure 8).
7.
2
Track Dimensions
7. 2. 1 Track Width The track width shall be 1.45mm (0.057 in) nominal.
7.2.2 Distances Between Tape Centerline and Track Edges
The distance between centerline of the tape and the outer
edges of the tracks shall be between 1.830mm (0.072 in)
and 1.905mm (0.075 in). The distance between the tape
centerline and the inner edges of the tracks shall be
between 0. 37mm (0. 015 in) and 0. 51 mm (0. 020 in).
7. 3 Track Designation
7. 3. 1 With side "A" up, the designation of the two tracks
is as follows.
When the tape moves from left to right with the
magnetic surface facing the observer, and with the
leader of side A to the right, the bottom track is
designated track No. 1 and the upper track is designated
track No. 2 (see Figure 1).
7. 3.2 The recording starts with track No. 1; at its con-
clusion the cassette may be turned over and the
recording can be continued with track No. 2.
7.4 Use of Tracks
The use of track No. 1 is reserved for data interchange. The
use of track No. 2 is to be indicated on the label. If it is
not used in the same way as track No. 1, reading of track No. 2
requires agreement between sender and recipient of the cassette.
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 Approved For Release 2002/05/17 : CIA-RDP83T00573R000600200003-4
7.5
Location of Characters on the Tracks
7.6
Each character is located in a byte (octet) of c fight
positions along the track numbered from 1 to B in
of recording.
Sequence of Recording
bit.-
order
The least significant bit is recorded first. The information
to be interchanged is recorded serially by bit and
by character.'
byte
Bit-positions: ...432 876543218765432...
Forward Tape Motion:
Resulting Recording
Direction-
7.7 Code
American National
The characters are represented by means of the / Standard
Code for Information Interchange (ASCII X3.4-1968) and
amendments thereto.
7.7.1 Recording of 7-bit Coded Characters --
Each 7-bit coded character is recorded In bit-
positions 1 to 7 of a byte; bit-position 8 is recorded
with value ZERO. The relationship is as follows-
.
Bits of the 7`-bit combination- 0 b7 b6 b5 b4
V
3
b2 b1
Bit-position in the byte: 8 7 6 5 4 3 2
7.7.2 Recording of E-Bit Coded Characters --
Bits of the 8-bit combinatiqn a8 a7 a6 a5. a4 a3 a2 a1
Bit-position in the byte- 8 7 6 5 4 3 2 1
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 Approved For Release 2002/05/17 : CIA-RDP83T00573R000600200003-4
7.8 Sequenc(: of Characters
The secj1!vn1_c of Lhoracters froin start t?v:nrd finish of a
block is corresponding
to the normal left to right sequence
of a writtcn line.
7. 9 Data f1o, I:
A data block shall consist of a preamble, data and postamble.
The- data portion of a data block including the CRC (see 7. 13)
shall contain a minimum of '32 bits and a maximum of 2064 bits.
7. 10 Control Block
A control block (lcnowr as tape mark) shall consist of a pre=
amble, two bytes of eight ZERO bits each, and a 'postamble.
7.11 Gaps
7.11.1 Integrity of gaps The gaps shall be DC erased. Iawediatily before and after each
block 'there shall be a length of at least 2.5mm (0.10 in) in
which, exclusive of the residual edge signals, there is no flux
discontinuity capable of producing a read signal of more than 10%
of one-half of the Standard Reference Amplitude. In the remiining
art ofithe.gap there shall be no more than seven (7) flux
p
transis
7. 11.2 Inte rblock gaps --
The interbiock gap defined as the distance between two
successive blocks shall have a. nominal length of
20. 3mm (0.8 in), shall have a minimum length of
17. 3mm (0. 70 in) and a maximum length of 250 nm
(9.8 in). Any gap in excess of 400nm (15.5 in)
sha'tl be considered end of data on this track.
7. 11. 3 Initiial gap --
The gap between the BOT marker and the first block
shall be 33mm (1. 3 in) minimum and 250mm (9.8 in)
max: imum.
7.11.4 Elongated gap --
The interblock gap is an elongated gap if its length
is between 50mm and 250mm (1. 97 in and 9.8 in).
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 Approved For Release 2002/05/17 : CIA-RDP83T00573R000600200003-4
7.11.5 Trailer gap --
The gap following the last block shall have a minimum
length of 17.8mm (0.70 in). At least 17.8mm
(0. 70 in) of this gap shall lie within the tested
area (see 4.2.5).
7. 12 Preamble and Postamble
7. 12. 1 Preamble - -
Immediately preceding data in each block, the preamble
111010101011 shall be written. When reading in the
forward direction, the first bit flux transition shall be
a ZERO transition.
7. 12. 2 Postamble - -
Immediately following data in each block, the postamble
,,10101010'' shall be written. When reading in the
forward direction, the first bit flux transition shall
be a ZERO transition.
7. 13 Cyclic Redundancy Check (CRC)
The last two characters in the data portion of a data block
shall be Cyclic Redundancy Check (CRC). The 16-bit CRC
shall be written in each data block following the data and
immediately preceding the postamble. The polynomial
generating the CRC is expressed as:
x16 + x15 + x2 + 1
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 Approved For Release 2002/05/17 : CIA-RDP83T00573R000600200003-4
rMI d," m@ M Clo sod to
CnOEV .1111.0 ....
I
to be d.l.rnl,odd
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FIp I SID(A,TRACKA,IIOLES AND ASYMMETRICAL SLOT
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to e4 ddld,m,hdd
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 Approved For Release 2002/05/17 : CIA-RDP83T00573R000600200003-4
Shaded waes
ligur? 2 811me oaenmge
oyr 1ne lull nwgnr of the
C ol.iIls '0er lure '.nab4f,.C Idd
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Fig 2 POSITION OF HEADS
(Dlmenelone In "Ch's)
Fig 3 TAPE GUIDES IN CASSETTE
(DlmalIl0M In lnchss)
2 6299
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m 11gur? 2 dehna 0less 9?
olar the 1.11 14.901 of 1M 11C I40
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weds ",,ad by
ahd Pr.s.wS Pod
(Oime Mfom m mml
Fig 3 TA4E GUIDES IN CASSETTE
(Dlmsnllan' In mm)
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 Approved For Release 2002/05/17 : CIA-RDP83T00573R000600200003-4
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Approved For Release 2002/05/17 : CIA-RDP8;3T00573R00,0600200003-4
..n ?s1, 3w t.,i'
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 Approved For Release 2002/05/17 :. CIA-RDP83T00573R000600200003-4
[=00-78[-Al
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boll. udee
EIq 5 CASSETTE SUPPORT PLANES
(D.men aloneppln mm)
Approved For Release 2002/05/17 CTA-RDP83TO0573RO0060020OTb'83-4
 Approved For Release 2002/05/17 : CIA-RDP83T00573R000600200003-4
b MA- LABEL AND WINDOW AREAS DIMENSIONS
(Dlmtntbnt m ~r nt,l
F -q b MAX 1 ABEL ANI) WINDOW ARE AS DIMENSIONS
ID-eneio.i In mm)
Approved For Release 2002/05/17 QIA-RDP83T00573R000600200003-4
 Approved For Release 2002/05/17 : CIA-RDP83T00573R000600200003-4
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f M
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Approved For Release 2002/05/17 : Z--RDP83T00573R000600200003-4
 Approved For Release 2002/05/17 : CIA-RDP83T00573R000600200003-4
GoosPl
4Q
0
tl-
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DO
\'NTEROLOCN GAP
'NITIAL GAP l`_J
I Ten s MO.n a 1h ou0? ..a. 0.1
O Tool .. lapl ?otu. oi. .0 ,he sass evecl.on w the
,0l bIb h 600 and the .0.1.01 1oP
O T.f bs, c.0, 01: M,s ( b a.IS) of the polo 06,9.0. .,*the
CFehe Red..dOncr Cbe,h(CNC)
O SNO.n .A.ouf Ohose Tlu. ,erelsal. that .na, 4101
F.6 4. RECORDING FORMAT Goo GPI
10...6.0,0110 ,0. l.CNee)
'NTEReLOC. GAP (?)
,i, a ln.n
0OSTAMBLE DATA PORTION P*EAMBLE
B BITS T 32 TO 2044 BITS giFS
U
I Too s s.o.n .,1h cud. s.do 001
2) Tope ,s (unp 9Olu,a100 .n the erase 4r.llae,. IM
,nlelbl0Ck lop 0.4 I.e -1,01 600
?M lost 1 cM10c111h (14 Wei of IM 0111 Oorb,. we fee
Cpcl.c R0s.n4oncf Cfece (CRC)
$.0....1-8.1 PMSo flu. .0.0104 4 1.af ?1ov .0,0,
oelleff0 sale 0.1$
F.1 a RECORDING 1 ORMAT )=boom
10.,.0.0,0.0 1. m,0)
L INITIAL GAP 2
Approved For Release 2002/05/17-22lEQA-RDP83T00573R000600200003-4
 Approved For Release 2002/05/17 : CIA-RDP83T00573R000600200003-4
APPENDEK A
Layer-to-Layer Adhesion
A piece of the tape to be tested, about 1 m (39 in) in length, shall
be wound around a glass pipe, 36 n:n in diaieter, with a tension of 3N,
(0.67 lb), and fixed at the end. This shall be stored for 24 hours
at a temperature of :5 + 3?C, (113?F _5?F and at 80": R.H. After this
period it shall be sacred for another 24 sours in the testing environ-
ment specified in Section 3. The tape shall than be unwound with a
weight of 5 grans at the end of tape as shown below, and the angle(e)
shall be smaller than 45'.
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 Approved For Release 2002/05/17 : CIA-RDP83T00573R00060020000-4
APPr"'TTX N
Z easurcc.ent. of Light Transmittance
B.1 Introduction
The deccriotion in the follcairg.p3-ragranhs outlines the rencral
principle o'' a test ce:_cc and the test met'-c-1 to be croloyed
when r.cacurin::, L^^ raaia;.ion (li'o:iL) transuitta:ice of r..a nctic
tape, includi::J leader.
For the purpose of this document I'light transmittance" is defined
by corner x_0:1 as the relaticrt~'in cetiec.'1 t.` .' ::'?':'1:.r:" o"'
from the test. C_'I_.ce with thert a:e 3amole in Se :ca and the reading
obtained h: en no sa"'c i e 2.z D:'ese nL. 1:,e Lra.^.s".Lar.ce value is
expressed a3 ,.he - ercer..c--z! . at_o of the two
the radiation (light) source
the optical path
the measuring mask-
the photo cell
the measuring equipment
B.2 Description of the Test Device
L.2.1 naula:Uon 1lignnc.) source
A tungsten lamp is used as the radiation (light) source and should
be operated in an udder-run state.
The colour temperature should be 20000 t: ? 200?K and.a resulting
illumination at the surface of the tape sample- of about 5000 lux is
recommended.
B.2.2 Optical path
The radiation should be ncr^endicular to the tape saiaole and be of
substantially uniform intensity. Typically the tape sample should be
separated from the lar-p by a distance- of 150 n-.,,.
A diaphragm of the fora.. shown in Figure ' Dl is recorr.:ended in order to
sensibly ensure that scattered radiation does not enter the mask area.
D.2.3 Measuring r.ask geometry
The measuring cask shall be constructed in one piece according to the
drawing shown in Figure 32. A good rhatL *black finish capable of
absorbinr, nfra-red radlat-ion is necessary.
Special care. runt be taken to ensure that the tape ,armle to be measured
is maintained flat in contact with the ir:ricr fa ere of the ma:;k.
Approved For Release 2002/05/17 `CIIA-RDP83T00573R000600200003-4
30-
The essential elements of the test device arei
 Approved For Release 2002/05/17 : CIA-RDP83T00573R000600200003-4
li.2.4 Photo_ull
A flat silicon r!.otocc :.l :-hould be used. Its dimensions must be such
that t~.e ac;;_ re:: of tre nnotoccll exceeds the diameter of the mask
orifice. It be i.,:e:ntcd parallel and ;.lose prod .it;; to the
outer face of ..he rusk.
B.2.5 treasuring EquiDr..ent
The neas ri:: e ,,.ii p^ent s!-.o 1d be connected c r ectly across the photocell
to measure the O:L7L' cu:''ent. 1n or.er to be able to Set the treasuring
equipment to 1`..11 scale ..:.le:tio:. ('_'13;) a shun. potertiometre in the
circuit ma!-:t be pro ri.?ed or a fine adjustment of the lamp power supply
voltage is required.
The, load ir-oed._nce ac:-oss the photocell should be as low as possible
and must no-, exceed 500.T,,. The instrument- should have a nominal
accuracy of ? 0.1;".
B.3 Test Procedure
B.3.1 For the purpose of the test a sample strip of tape not shorter than
250nm is used.
- The measuring equipment is set to full scale reading represe:tirg
(100%).
The sample strip is inserted and 1-5 obse_-vatior.s on different points
along the s`:mpie are recorded.
-'The sample strio is then withdrawn and ".011 scale deflection (100%)
is re-chec.:ec. If the rooad_ng lies ou-side '1 1- of 99 to
101% the equipment is reset to 100'j and a new set of 45 observations
B.4 Guidance on Construction
B.4.1 Experience has shown that a projector lamp is most suited as the radia-
tion source. when selecting a lamp, care .. be taken to avoid a la:--p
with optical _rhomogenities in the glass enve_c^,e. rilso, if mirrors
or lenses are used in the optical path, they must be placed such that
no filament cccurs in the pre: it ~? of the nask and photocell
area. It is necessary to overate the lam- from a stabilized, regulated
power supply.
B.4.2 Special attention must be paid to all surfaces parallel to the optical
path and in close proximity to the mask and photocell to avoid reflection the mcthcd of insert .. he ; ensure that
f light. Similarly, ~ t. ,ape, must ens~s ~no ambient light leaks througin any slot parr ang,rmetit.
B.4.3 The accuracy of the meacuremant is dercr.dent not inly an attaining
the dimensicnc1 tolerances :ho:rn in Fire 2, b, ,;L on the subse-
quent coatis ,, of the 6uriaces with a h=-h quality optical matt black
paint. The rack sheuia be checked alter coating +.o ensure thit the
small hole remains in tolerance. The acti-.od of holding the sacrvie
-31-
Approved For Release 2002/05/17 : CIA-RDP83T00573R000600200003-4
 Approved For Release 2002/05/17 : CIA-RDP83T00573R000600200003-4
mug , hr, suc:lr '.', '`, the t s r..azr:; i r.:d fl~:c,
of contact. with the face
mask. all().: the saralc to be moved without
phy is .1 or
B.4.4 The photocell -..:ust be rN?r,ted with care, taking z ecial precaution that
~--ranf-cment. It
is adv:.s:rblc the of the p otc-:ell p:?k:,:;e3 slic
htly oa the
outer face of the mask.
B.4.5 An effective r?n:nt or o i i''. i 3eal ;
por~te3 by _..... ~_, y n c-21 ='` -c-^ should be incar-
- or 0'
mat transmittance and a
filter glass --an
nce.
B.4.6
The test device should be clccned
,PC
icdicaily.
Approved For Release 2002/05/1 T3?E 1A-RDP83T00573R000600200003-4
 Approved For Release 2002/05/17 : CIA-RDP83T00573R000600200003-4
INTERMEDIATE
MASK
d = approx. 150 mm
FIGURE BI MEASURING DEVICE (DIAGRAM}
Approved For Release 2002/05/17 : CIA-RDP83T00573R000600200003-4
 Approved For Release 2002/05/17 : CIA-RDP83T00573R000600200003-4
INNER
FACE
FACE ~'$+G, I
GROOVE FOR FRONTSIDE
CONNECTIONWIRE OF PHOTOCELL
* DETERMINED BY USER
FIGURE B2 MEASURING MASK
Approved For Release 2002/05/17 : CIA-RDP83T00573R000600200003-4
 Approved For Release 2002/05/17 : CIA-RDP83T00573R000600200003-4
Expository Remarks Supporting the AN Standard
Magnetic Tape Casset.c for Lniormation L. tcrchange
(Co-Planar 0. 150 INCH 800 BPI PE)
CONTENTS
SECTION
RI Introduction
R2 Rational for Selecting Cassette and Format Used
R3 Future Development
R4 Tape Mark
R5 Preamble and Postamble
R6 Cyclic Redundancy Check (CRC) Character
Approved For Release 2002/05/17: CIA-RDP83T00573R000600200003-4
-35-
 Approved For Release 2002/05/17 : CIA-RDP83T00573R000600200003-4
R1 INT RO1)JCTION
In the dcvelu.~~unt of this standard the Phili:>s "Compact
Cassette" was ta;cen as the po:nL of departure bcc