ANSI INCITS 54-1986 Information Systems - Recorded Magnetic Tape for Information Interchange - (6250 CPI Group-Coded Recording).pdf

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1、for Information Systems - Recorded Magnetic Tape for Information Interchange - (6250 CPI, Group-Coded Reco I ANSIINCITS 54-1986 (R1997) (formerly ANSI X3.54-1986 (RI 997) rding) Developed by Where IT all begins Approval of an American National Standard requires review by ANSI that the requirements f

2、or due process, consensus, and other criteria for approval have been met by the standards developer. Consensus is established when, in the judgment of the ANSI Board of Standards Review, substantial agreement has been reached by directly and materially affected interests. Substantial agreement means

3、 much more than a simple majority, but not necessarily unanimity. Consensus requires that all views and objections be considered, and that a concerted effort be made toward their resolution. The use of American National Standards is completely voluntary; their existence does not in any respect precl

4、ude anyone, whether he has approved the standards or not, from manufacturing, marketing, purchasing, or using products, processes, or procedures not conforming to the standards. The American National Standards Institute does not develop standards and will in no circumstances give an interpretation o

5、f any American National Standard. Moreover, no person shall have the right or authority to issue an interpretation of an American National Standard in the name of the American National Standards Institute. Requests for interpretations should be addressed to the secretariat or sponsor whose name appe

6、ars on the title page of this standard. CAUTION NOTICE: This American National Standard may be revised or withdrawn at any time. The procedures of the American National Standards Institute require that action be taken periodically to reaffirm, revise, or withdraw this standard. Purchasers of America

7、n National Standards may receive current information on all standards by calling or writing the American National Standards Institute. American National Published by American National Standards Institute 11 West 42nd Street, New York, New York 10036 Copyright O1 986 by Information Technology Industr

8、y Council (ITI) All rights reserved. No part of this publication may be reproduced in any form, in an electronic retrieval system or otherwise, without prior written permission of ITI, 1250 Eye Street NW, Washington, DC 20005. Printed in the United States of America ANSI X3.54- 1986 Revision of ANSI

9、 X3.54-1976 American National Standard for Information Systems - Recorded Magnetic Tape for Information Interchange - (6250 CPI, Group-Coded Recording) Secretariat Computer and Business Equipment Manufacturers Association Approved March 26, 1986 American National Standards Institute, Inc (This Forew

10、ord is not part of American National Standard X3.54-1986.) Foreword This standard presents format and recording requirements for 1/2-inch, 9-track magnetic tape to be used for information interchange among information processing systems, com- munication systems, and associated equipment utilizing th

11、e American National Standard for Information Systems - Coded Character Sets - 7-Bit American National Standard Code for Information Interchange (7-Bit ASCII), ANSI X3.4-1986. This standard deals solely with recording on magnetic tape and complements American National Standard Unrecorded Magnetic Tap

12、e for Information Interchange (9-Track 200 and 800 CPI, NRZI, and 1600 CPI, PE), ANSI X3.40-1983. The X3B1 Subcommittee on Magnetic Tape, which developed this standard, consists of a group of experienced and qualified specialists on recording of digital information on mag- netic tape. In the develop

13、ment of this standard careful consideration was given to current practices, existing equipment and supplies, and the broadest possible acceptance, and to providing a basis for future improvement in the use of the medium. This standard was approved as an American National Standard by ANSI on March 26

14、, 1986. Suggestions for improvement of this standard will be welcome. They should be sent to the Computer and Business Equipment Manufacturers Association, 3 11 First Street, NW, Washington, DC 2001 1. This standard was processed and approved for submittal to ANSI by the Accredited Standards Committ

15、ee on Information Processing Systems, X3. Committee approval of this standard does not necessarily imply that all committee members voted for its approval. At the time it approved this standard, the X3 Committee had the following members: Edward Lohse, Chair Richard Gibson, Vice-Chair Catherine A. K

16、achurik, Administrative Secretary Organization Represented Name of Representative American Express. D. L. Seigal Lucilie Durfee (Alt) American Library Association. . Paul Peters American Nuclear Society. . Geraldine C. Main D. R. Vondy (Ait) AMP Incorporated Patrick E. Lannan Edward Kelly (Alt) Asso

17、ciation for Computing Machinery . Kenneth Mage1 Jon A. Meads (Alt) Association of the Institute for Certification of Computer Professionals. Thomas M. Kurihara AT 1600 CPI, PE; and 6250 CPI, GCR), ANSI X3.40-1983, where the following are dealt with in detail: general requirements, definitions, tape

18、physi- cal and magnetic requirements, and tape reel require- ments. Compliance with the standard for unrecorded tape is a requirement for information interchange. The use of a labeling standard such as American National Standard Magnetic Tape Labels and File Structure for Information Interchange, AN

19、SI X3.27-1978 will sup- port data interchange between data processing systems. CAUTION NOTICE: The users 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 re

20、spect to the validity of this claim or of any patent rights in connection therewith. The patent holder has, however, filed a statement of wiiiingness to grant a license under these rights on reasonable and nondiscriminatory terms and conditions to applicants desiring to obtain such a license. Detail

21、s 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 This standard defines the requirements and sup- porting test methods necessary to ensure interchange at acc

22、eptable performance levels. It is distinct from a specification in that it delineates a minimum number of restrictions consistent with compatibility in inter- change transactions. 1.3 The performance levels contained in this standard represent the minimum acceptable levels of perfor- mance for inter

23、change purposes. They, therefore, rep- resent the performance levels which the interchanged items should meet or surpass during their useful life and thus define end-of-life criteria for interchange purposes. The performance levels in this standard are not intended to be employed as substitutes for

24、pur- chase specifications. 1.4 Wherever feasible, quantitative performance levels that must be met or exceeded in order to comply with this standard are given. In all cases, including those in which quantitative limits for requirements falling with- in the scope of this standard are not stated but l

25、eft to agreement between interchange parties, standard test method and measurement procedures shall be used to determine such limits. 1.5 U.S. engineering units are the original dimensions in this standard. Conversions of toleranced dimensions from customary U.S. engineering units (similar to Brit-

26、ish Imperial Units) to SI units have been incorporated in this standard according to Method A as described in American National Standard Metric Practice, ANSI/ IEEE 268-1982, and in International Standard for Toleranced Dimensions - Conversion from Inches into Millimetres and Vice Versa, IS0 370-197

27、5. Method A should be used to achieve economy unless a require- ment for absolute assurance of fit justifies use of Method B. In the national standards of IS0 member bodies, additional rounding may be done to produce “preferred ” values. These values should lie within or close to the original tolera

28、nce. 1.6 Except as indicated in 1.4, interchange parties complying with the applicable standards should be able to achieve compatibility without need for addi- tional exchange of technical information. 7 AMERICAN NATIONAL STANDARD X3.54-1986 2. Referenced Standards, 2.1 American National Standards.

29、This standard is in- tended for use in conjunction with the following Ameri- can National Standards. When these standards are superseded by a revision approved by the American Na- tional Standards Institute, Inc, the revision shall apply. ANSI X3.4-1986, Information Systems - Coded Char- acter Sets

30、- 7-Bit American National Standard Code for Information Interchange (7-Bit ASCII) ANSI X3.22-1983, Recorded Magnetic Tape for Infor- mation Interchange (800 CPI, NRZI) ANSI X3.27-1978, Magnetic Tape Labels and File Structure for Information Interchange ANSI X3.40-1983, Information Systems - Unrecord

31、ed Magnetic Tape for Information Interchange (9-Track 800 CPI, NRZI; 1600 CPI, PE; and 6250 CPI, GCR) ANSI X3.41-1974, Code Extension Techniques for Use with the 7-Bit Coded Character Set of American Na- tional Standard Code for Information Interchange ANSI X3.64-1979, Additional Controls for Use wi

32、th American National Standard Code for Information Interchange ANSI/IEEE 268-1982, Metric Practice 2.2 Other Standards. This standard is also intended to be used in conjunction with the following standards: IS0 370-1975, Toleranced Dimensions - Conversion from Inches into Millimetres and Vice Versal

33、 IS0 5652-1984, Information Processing - 9-Track, 12, mm (0.5 in) Wide Magnetic Tape for Information Interchange - Format and Recording, Using Group Coding at 246 cpmm (6 250 cpi) 3. Definitions alternate record code. Five bits along any track repre- senting encoded 4 bits of data, padding character

34、s, check characters, residual characters, or a combination of these characters, on tape. automatic read amplification (ARA) identification (ID) burst. A special control block used at the end of the ARA burst to identify the ARA burst when reading backward to the load point. Copies are available from

35、 the American National Standards Institute, 1430 Broadway, New York, NY 10018. automatic read amplification (ARA) level burst. A string of bits in all tracks for setting up the amplifiers. auxiliary cyclic redundancy check (CRC) character. A CRC character usable for error-detection purposes. beginni

36、ng-of-tape (BOT) marker. A photoreflective marker placed on the tape for the purpose of indicating the beginning of the usable recording area. block. A group of contiguously recorded single-byte characters considered and transported as a unit. byte. A contiguous set of 8 bits that are acted on as a

37、unit. character. A unit of information usually constituted as one or more bytes as defined in 3.8. control subgroups. Special subgroups of characters that (except for the subgroup containing the last char- acter) have sets of identical control five-serial-bit values in the nine tracks. end mark. A s

38、ubgroup used to demark the residual group. When the media movement is in a forward direc- tion, it denotes that the next group is the residual group. Mark 1. A subgroup used to demark data groups from other control subgroups. When the media move- ment is in a forward direction, it denotes the onset

39、of data groups. Mark 2. A subgroup used to demark data groups from other control subgroups. When the media move- ment is in a forward direction, it denotes the onset of other control subgroups. second control subgroups. The second subgroup and next to last subgroup of a record. sync control subgroup

40、. A subgroup used to indi- cate recorded frequency and phase to allow synchroni- zation of the variable-frequency clock (VFC). terminator control subgroups. The first subgroup and last subgroup of a record. cyclic redundancy check (CRC) characters. Characters usable for error detection. cyclic redun

41、dancy check (CRC) data group. A specially formatted data group containing one of the CRC char- acters, the residual character, and an error-correcting code (ECC) character. data density. The number of single-byte characters stored per unit length of tape, usually expressed as characters per inch (cp

42、i), or characters per millimeter (cpmm). data group. Seven bytes plus an ECC character accumu- lated as a group prior to the record code value trans- lation. 8 AMERICAN NATIONAL STANDARD X3.54-1986 density identification area (ID burst). A burst recording at the beginning of a tape identifying the u

43、se of the group coded recording method. end-of-tape (EOT) marker. A photoreflective marker placed on the tape for the purpose of indicating the approaching end of the usable recording area. error-correcting code (ECC) character. A special char- acter usable for error detection and correction. flux s

44、pacing. The space between successive flux transi- tions. flux transition position. The point that exhibits the maximum free-space surface flux density normal to the tape surface. group-coded recording (GCR). A recording technique that collects groups of bits and encodes them prior to putting them on

45、 tape. interblock gap. A DC-erased section of tape separating blocks of information. last character. The last character in each block, which restores magnetic remanence in all tracks to the DC erase polarity. master standard amplitude reference tape. An ampli- tude reference tape that has been selec

46、ted by the Na- tional Bureau of Standards (NBS) to establish the ref- erence level for average peak-to-peak signal amplitude output when recorded with continuous ONES at 9042 ftpi (356 ftpmm) on a master measurement system. padding character. A character consisting of all ZEROS with odd parity. phys

47、ical recording density. The number of recorded flux transitions per unit length of track, e.g., flux trans- itions per inch (ftpi) or flux transitions per millimeter (ftpmm). postamble. Groups of special signals recorded at the end of each block on tape for the purpose of electronic synchronization.

48、 preamble. Groups of special signals recorded at the be- ginning of each block on tape for the purpose of elec- tronic synchronization. record. A set of related data treated as a unit of infor- mation. record code. The coded representation of data, padding characters, check characters, and residual

49、characters on tape. residual character. The character that occupies the seventh group position of the CRC data group and con- tains two data byte counts, one to modulo 7 and one to modulo 32. residual group. The group that contains the extra char- acters (the remainder of the number of characters di- vided by 7), an auxiliary CRC character, and an ECC character. Each such extra character is a residual char- acter. resync burst. A set of control subgroups identifying format resynchronization points in a block. It is in- tended that read-back circuits be able to resychronize operations when