1、ANSI INCITS 250-1996 (R2001)(formerly ANSI X3.250-1996 (R2001)for Information Technology Recorded Magnetic TapeMini Cartridge forInformation Interchange 12/24-Track, Serial,0.250 inch (6.35 mm)10,000 bpi (394 bpmm)Group-Coded RecordingANSIX3.250-1996American National Standardfor Information Technolo
2、gy Recorded Magnetic Tape Mini Cartridgefor Information Interchange 12/24-Track, Serial, 0.250 inch (6.35 mm)10,000 bpi (394 bpmm) Group-Coded RecordingSecretariatInformation Technology Industry CouncilApproved June 5, 1996American National Standards Institute, Inc.AmericanNationalStandardApproval o
3、f an American National Standard requires review by ANSI that therequirements for due process, consensus, and other criteria for approval havebeen met by the standards developer.Consensus is established when, in the judgment of the ANSI Board of StandardsReview, substantial agreement has been reached
4、 by directly and materiallyaffected interests. Substantial agreement means much more than a simplemajority, but not necessarily unanimity. Consensus requires that all views andobjections be considered, and that a concerted effort be made toward theirresolution.The use of American National Standards
5、is completely voluntary; their existencedoes not in any respect preclude anyone, whether he has approved the standardsor not, from manufacturing, marketing, purchasing, or using products, processes,or procedures not conforming to the standards.The American National Standards Institute does not devel
6、op standards and will inno circumstances give an interpretation of any American National Standard.Moreover, no person shall have the right or authority to issue an interpretation ofan American National Standard in the name of the American National StandardsInstitute. Requests for interpretations sho
7、uld be addressed to the secretariat orsponsor whose name appears on the title page of this standard.CAUTION NOTICE: This American National Standard may be revised orwithdrawn at any time. The procedures of the American National StandardsInstitute require that action be taken periodically to reaffirm
8、, revise, or withdrawthis standard. Purchasers of American National Standards may receive currentinformation on all standards by calling or writing the American National StandardsInstitute.Published byAmerican National Standards Institute11 West 42nd Street, New York, New York 10036Copyright 1996 by
9、 Information Technology Industry Council (ITI)All rights reserved.No part of this publication may be reproduced in anyform, 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 AmericaiContents
10、PageForeword .iv1 Scope, purpose, and conformance 12 Normative references23 Definitions 24 Recording .45 Tracks 66 Tape format 117 Frames .238 Blocks.249 Error control2410 Interleave organization2811 Parallel recording2812 Format-time responsibilities.2813 Run-time responsibilities .34Tables1 Encodi
11、ng 52 12 Track format.83 24 Track format.94 SOD .115 Record-type marker.126 Track number147 Thread number .148 Frame number 159 Error control method .1510 Current frame counter per block 1511 Total frames per block.1612 Redundancy1613 Dispersion factor.1614 Data field length1715 Interleave factor 17
12、16 Parallel recording1717 Overlapped .1718 Frames per track.1819 Tracks per tape.19ii20 Post-data gap .1921 Post-ID gap.1922 Drive specification.2023 Positioner type 2024 Current year2025 Current month.2026 Current day.2027 Current hour .2128 Current minute 2129 Current second .2130 Track specificat
13、ion 2131 Lot number .2232 Manufacturers ID2233 Interleave organization2934 Parallel recording29Figures1 Rate of change .52 Instantaneous flux transition spacing.73 Even and odd tracks .74 Trim/Straddle erase R/W heads.105 Wide-write/Narrow-read R/W heads.106 Generalized record117 The data field128 I
14、D field of ID record.139 ID field of non-ID record 1310 Overlapped data .1811 Non-overlapped data.1812 CRC code field2313 Generalized frame organization.2514 Frame and starting frame layout 2515 Block and blocks on one track .2516 CRCC without pre-multiplication 2617 CRCC with pre-multiplication.261
15、8 Interleave factor 2 .2719 Interleave factor 3 .27Pageiii20 A manufacturers frame .2921 Flawed-frame list entry3122 Uselog 3123 Uselog control block3124 Alternate frame list3325 Format descriptor list 33AnnexA Physical block to logical block re-mapping in the overlapped data mode.36PageivForeword (
16、This foreword is not part of American National Standard X3.250-1996.)This standard presents the minimum requirements for serial recording of 12/24tracks on a 0.250-in (6.35-mm) magnetic tape mini cartridge at 10,000 bpi (394bpmm) using group-coded recording. It is one of a series of standards used f
17、orinformation interchange and requires compliance with the American NationalStandard for Information technology Unrecorded magnetic tape mini-cartridgefor information interchange 0.25 in (6.35 mm), 10 000-14 700 ftpi (394579ftpmm) Coercivity 550 oersteds (44 000 amperes/meter) (Types 2000, 2060,2080
18、, 2120), ANSI X3.249-1995. Also included is an informative annex that givesinformation on physical to logical block re-mapping in the overlapped data mode.This standard was developed by Technical Committee X3B5 on DigitalMagnetic Tape. This group consists of experienced and qualified specialistson t
19、he recording of digital information on magnetic tape. In the developmentof this standard, careful consideration was given to current practices, exist-ing equipment, and supplies, achieving the broadest possible acceptance,and providing a basis for future improvement in the use of the medium.This sta
20、ndard contains one informative annex which is not considered partof this standard.Requests for interpretation, suggestions for improvement or addenda, ordefect reports are welcome. They should be sent to the InformationTechnology Industry Council, 1250 Eye Street, NW, Suite 200,Washington, DC 20005.
21、This standard was processed and approved for submittal to ANSI by theAccredited Standards Committee on Information Technology, X3.Committee approval of this standard does not necessarily imply that allcommittee members voted for its approval. At the time it approved thisstandard, the X3 Committee ha
22、d the following members:James D. Converse, ChairDonald C. Loughry, Vice-ChairKate McMillan, SecretaryOrganization Represented Name of RepresentativeAmerican Nuclear SocietyGeraldine C. MainSally Hartzell (Alt.)AMP, Inc. Edward KellyCharles Brill (Alt.)Apple Computer, IncDavid K. MichaelJerry Kellenb
23、enz (Alt.)ATb) After prolonged operation over a limitedarea;c) When the temperature change to whichthe cartridge has been exposed is greaterthan 17C (30F).4.2 MethodThe method of recording shall be the “non-return to zero, change on one” (NRZ1) wherea ONE is represented by a flux transitionoccurring
24、 in the center of the bit-cell and aZERO is represented by the absence of a fluxtransition in the bit-cell.4.3 EncodingEach 8-bit data byte is separated into two 4-bit groups. Each 4-bit group is encoded into a5-bit GCR group for recording on the magnet-ic tape cartridge. The most significant group
25、isrecorded first. The encoded data has theproperty that no more than two consecutiveZEROs shall occur. The translation table fordata groups (B3, B2, B1, B0) and GCR groups(G4, G3, G2, G1, G0) shall be in accordancewith table 1. GCR bit G4 is recorded first.3.31 parallel recording: A technique forsim
26、ultaneously recording two or more recordsindependently on two or more tracks.3.32 physical block: A block whose loca-tion is determined by defined calculationsbased on the number of frames per track andinterleave.3.33 physical recording density: Thenumber of recorded flux transitions per unitlength
27、of track, e.g. flux transitions per inch(ftpi) or flux transitions per millimeter (ftpmm).3.34 postamble: A sequence of binary bitsrecorded at the end of each record on a mag-netic tape to isolate data from the DC tapemagnetization between data frames.3.35 preamble: A sequence of binary char-acters
28、recorded at the beginning of eachrecord on a magnetic tape to provide electron-ic synchronization when reading in the for-ward direction of tape travel.3.36 record: A group of consecutive bitscomprising the preamble, start-of-data mark-er, record-type marker, optional data field, IDfield, CRCC, and
29、postamble.3.37 reference tape cartridge: A magnetictape cartridge selected for a specific propertyto be used for calibrating purposes.3.38 reverse direction: Tape motion fromtake-up reel (EOT end) to supply reel (BOT end).3.39 secondary reference amplitude tapecartridge: A tape cartridge intended fo
30、r rou-tine calibrating purposes, the performance ofwhich is known and stated in relation to thatof the Reference Tape Cartridge.NOTE Secondary reference tapes are availablefrom the 3M Company, St. Paul, Minnesota,55144. Contact the local 3M sales representativeor telephone (612) 733-2172 and order p
31、art num-ber 84-9801-9283-9.3.40 signal amplitude reference tape car-tridge: A reference tape cartridge selectedas a standard for signal amplitude and refer-ence field.3.41 standard reference amplitude: Theaverage peak-to-peak signal amplitude outputof the master standard reference tape car-tridge wh
32、en it is recorded on the standardmeasurement system at the maximum fluxdensity specified in this standard.ANSI X3.250-19964marker, as described in clause 6, Tape format.The short-term average bit-cell length shall bewithin 7% of the nominal bit-cell length.4.6.4 Rate of changeThe rate of change of t
33、he bit-cell length shallnot exceed 0.25%. The rate of change isgiven by the relationship in figure 1.Rate of change = Where t1, t2, and t3 are the times between fluxtransitions as shown below. Periods 1 through5 are contiguous and represent the repetitivedata pattern 101010 within a data block:(t1/4
34、) (t2/4)t3/531 542t1t2t3Figure 1 Rate of changeANSI X3.250-19964.4 Nominal densityThe maximum nominal density (flux transition inevery bit-cell) shall be 12 500 ftpi (492 ftpmm).4.5 Nominal bit-cell lengthThe nominal bit-cell length shall be 80.00 in(2.03 mm).4.6 Average bit-cell length variations4.
35、6.1 Average bit-cell lengthThe average bit-cell length is the distancebetween n+1 flux transitions divided by n.4.6.2 Long-term average bit-cell lengthThe long-term average bit-cell length shall bethe average bit-cell length measured over thedata fields of 20 contiguous frames. The long-term average
36、 bit-cell length shall be within 5% of the nominal bit-cell length.4.6.3 Short-term average bit-cell lengthThe short-term average bit-cell length shall bethe average bit-cell length measured over 16 bit-cells of the preamble prior to the start-of-data54 BIT GROUP 5 BIT GROUPHex B3 B2 B1 B0 G4 G3 G2
37、G1 G0 HEX0 0 0 0 0 1 1 0 0 1 191 0 0 0 1 1 1 0 1 1 1B2 0 0 1 0 1 0 0 1 0 123 0 0 1 1 1 0 0 1 1 134 0 1 0 0 1 1 1 0 1 1D5 0 1 0 1 1 0 1 0 1 156 0 1 1 0 1 0 1 1 0 167 0 1 1 1 1 0 1 1 1 178 1 0 0 0 1 1 0 1 0 1A9 1 0 0 1 0 1 0 0 1 09A 1 0 1 0 0 1 0 1 0 0AB 1 0 1 1 0 1 0 1 1 0BC 1 1 0 0 1 1 1 1 0 1ED 1 1
38、 0 1 0 1 1 0 1 0DE 1 1 1 0 0 1 1 1 0 0EF 1 1 1 1 0 1 1 1 1 0FTable 1 Encoding4.10 Signal amplitude4.10.1 Average signal amplitudeThe average peak-to-peak signal amplitude ofan interchanged tape at 12 500 ftpi (492ftpmm) shall deviate no more than +50% or35% from the average standard referenceamplitu
39、de. This averaging shall be made overthe central 100 flux transitions of the 125 con-tiguous flux transitions of the preambles of atleast 120 non-ID records.4.10.2 Maximum signal amplitudeThe peak-to-peak signal amplitude of anyinterchanged tape recorded at 4167 ftpi (164ftpmm) shall be less than 3
40、times the averagestandard reference amplitude.4.10.3 Minimum signal amplitudeTo be considered valid, a frame of an inter-changed tape shall contain no flux transitionswhose base-to-peak amplitude is less than25% of half of the average standard referenceamplitude.4.11 OverwriteOn an interchange tape
41、recorded with thelongest wavelength and overwritten with theshortest wavelength, the base-to-peak ampli-tude of residual long wavelength signal leftfrom previously recorded data shall notexceed 3% of half of the average standard ref-erence amplitude.4.12 AzimuthThe angular deviation of the mean flux
42、 transi-tion lines from the line normal to the tape car-tridge reference edge shall be less than 9minutes of arc (2.6 milliradian).5 Tracks5.1 Number and use of tracksThere shall be 12 or 24 tracks. Even num-bered tracks shall be recorded in the forwarddirection of tape movement. Odd numberedtracks
43、shall be recorded in the reverse direc-tion of tape movement.4.7 Instantaneous flux transition spacingThe instantaneous spacing between flux tran-sitions is influenced by the writing process,the pattern recorded (pulse crowding effect)and other factors. Instantaneous spacingsbetween flux transitions
44、 shall satisfy the fol-lowing conditions:In a sequence of flux transitions defined by bitpattern 11100111, the center flux transitions,designated by “Xs” in figure 2, of each group ofONEs is called a Reference Flux Transition.This pattern is present in every record in thelast 4-bits of the start-of-
45、data marker and thefirst 4-bits of the record-type marker. The max-imum displacement of flux transitions betweenthe reference flux transitions shall not deviateby more than 35% of the nominal bit-cell length(d1), averaged over the five bit-cells betweenthe reference flux transitions indicated in the
46、bit pattern in figure 2.The tolerance of the long-term average spac-ing and of the short-term average spacing areincluded in this deviation.4.8 Signal amplitude secondary referencetape cartridgeA signal amplitude secondary reference tapecartridge is a magnetic tape cartridge that hasbeen calibrated
47、against a Standard ReferenceAmplitude Tape, which has been selected asa standard for signal amplitude when record-ed at 12 500 ftpi (492 ftpmm). (See clause3.27 NOTE.)4.9 Average standard reference amplitudeThe average standard reference amplitude isthe peak-to-peak signal amplitude averagedover a m
48、inimum of 12 500 consecutive fluxtransitions derived from the signal amplitudesecondary reference tape cartridge when it isrecorded at a density of 12 500 ftpi (492ftpmm) and at a recording current of between155% and 165% of the current required toproduce the Reference Field at 12 500 ftpi(492 ftpmm
49、). The reference field is a minimumfield which, when applied to the signal ampli-tude secondary reference tape cartridge,causes a signal output equal to 95% of themaximum achievable output at the specifiedtest density.ANSI X3.250-19966ANSI X3.250-19965.1.1 Even and odd tracksData for interchange shall be recordedbetween the load-point marker and the early-warning marker as shown in figure 3.5.1.1.1 Even tracksEven tracks shall be recorded in the forwarddirection only. All even tracks shall start aminimum of 3 in (76mm) and a maximum of 4i
