1、Standard ECMA-2492ndEdition - June 1998Standardizing Information and Communication SystemsPhone: +41 22 849.60.00 - Fax: +41 22 849.60.01 - URL: http:/www.ecma.ch - Internet: helpdeskecma.ch8 mm Wide Magnetic TapeCartridge for InformationInterchange - Helical ScanRecording - DA-2 Format.Standard ECM
2、A-249June 1998Standardizing Information and Communication SystemsPhone: +41 22 849.60.00 - Fax: +41 22 849.60.01 - URL: http:/www.ecma.ch - Internet: helpdeskecma.chMB E-249-ii.doc 03-07-98 11,098 mm Wide Magnetic TapeCartridge for InformationInterchange - Helical ScanRecording - DA-2 Format.Brief H
3、istoryECMA has produced a series of Standards for cassettes and cartridges containing magnetic tapes of different widths andcharacteristics. Of these, the following relate to helical scan recording.ECMA-139 (1990) 3,81 mm Wide Magnetic Tape Cartridge for Information Interchange - Helical Scan Record
4、ing - DDS formatECMA-145 (1990) 8 mm Wide Magnetic Tape Cartridge for Information Interchange - Helical Scan RecordingECMA-146 (1990) 3,81 mm Wide Magnetic Tape Cartridge for Information Interchange - Helical Scan Recording - DATA/DAT FormatECMA-150 (1991) 3,81 mm Wide Magnetic Tape Cartridge for In
5、formation Interchange - Helical Scan Recording - DDS-DC Format using 60m and 90m Length Tapes, 2nd EditionECMA-169 (1992) 8 mm Wide Magnetic Tape Cartridge Dual Azimuth Format for Information Interchange - HelicalScan RecordingECMA-170 (1992) 3,81 mm Wide Magnetic Tape Cartridge for Information Inte
6、rchange - Helical Scan Recording - DDS format using 60m and 90m Length TapesECMA-171 (1992) 3,81 mm Wide Magnetic Tape Cartridge for Information Interchange - Helical Scan Recording - DATA/DAT-DC Format using 60m and 90m Length TapesECMA-198 (1995) 3,81 mm Wide Magnetic Tape Cartridge for Informatio
7、n Interchange - Helical Scan Recording - DDS-2 Format using 120m Length TapesECMA-210 (1995) 12,65 mm Wide Magnetic Tape Cartridge for Information Interchange - Helical Scan Recording - DATA-D3-1 FormatECMA-236 (1996) 3,81 mm Wide Magnetic Tape Cartridge for Information Interchange - Helical Scan Re
8、cording - DDS-3 Format using 125m Length TapesECMA-246 (1998) 8 mm Wide Magnetic Tape Cartridge for Information Interchange - Helical Scan Recording AIT-1 FormatECMA-247 (1998) 8 mm Wide Magnetic Tape Cartridge for Information Interchange - Helical Scan Recording HH-1 FormatECMA-248 (1998) 12,65 mm
9、Wide Magnetic Tape Cassette for Information Interchange - Helical Scan Recording - DTF-1This ECMA Standard specifies a magnetic tape cartridge. The DA-2 format will provide a storage capacity of 20 Gbytes ofuncompressed user data or typically 40, Gbytes of compressed user data.ECMA Standard has been
10、 adopted as 2ndEdition of ECMA-249 by the ECMA General Assembly of June 1998.- i -Table of contentsSection 1 - General 11 Scope 12 Conformance 12.1 Magnetic tape cartridges 12.2 Generating drive 12.3 Receiving drive 13 References 14 Definitions 14.1 a.c. erase 14.2 algorithm 14.3 append point 14.4 A
11、verage Signal Amplitude 24.5 azimuth 24.6 back surface 24.7 bit cell 24.8 byte 24.9 cartridge 24.10 Channel bit 24.11 Cluster 24.12 Cyclic Redundancy Check (CRC) character 24.13 Digital Sum Variation (DSV) 24.14 Error Correcting Code (ECC) 24.15 File Mark 24.16 flux transition spacing 24.17 Logical
12、Beginning of Partition (LBOP) 24.18 Logical Block 24.19 magnetic tape 24.20 Master Standard Reference Tape 24.21 Partition 34.22 Physical Beginning of Partition (PBOP) 34.23 Physical Beginning of Tape (PBOT) 34.24 Physical End of Partition (PEOP) 34.25 Physical End of Tape (PEOT) 34.26 physical reco
13、rding density 34.27 Read Back Check (RBC) 34.28 Reference Field 34.29 Secondary Standard Reference Tape (SSRT) 34.30 Set Mark 34.31 Standard Reference Amplitude (SRA) 34.32 Standard Reference Current (Ir) 34.33 Tape Reference Edge 34.34 Test Recording Current (TRC) 34.35 Track 44.36 Typical Field 45
14、 Conventions and Notations 45.1 Representation of numbers 45.2 Names 45.3 Reserved fields 4- ii -6 Acronyms 47 Environment and Safety 57.1 Testing environment 57.2 Operating environment 57.3 Storage environment 57.4 Transportation 57.5 Safety 57.6 Flammability 5Section 2 - Requirements for the case
15、68 Dimensional and mechanical characteristics of the case 68.1 General 68.2 Overall dimension 68.3 Holding areas 78.4 Cartridge insertion 78.5 Window 88.6 Loading grips 88.7 Label areas 88.8 Datum areas and datum holes 98.9 Support areas 108.10 Recognition holes 108.11 Write-inhibit hole 118.12 Pre-
16、positioning surfaces 118.13 Cartridge lid 118.14 Cartridge reel lock 138.15 Reel access holes 138.16 Interface between the reels and the drive spindles 148.17 Light path 158.18 Position of the tape in the case 168.19 Tape path zone 168.20 Tape access cavity 168.21 Tape access cavity clearance requir
17、ements 16Section 3 - Requirements for the Unrecorded Tape 339 Mechanical, physical and dimensional characteristics of the tape 339.1 Materials 339.2 Tape length 339.2.1 Length of magnetic tape 339.2.2 Length of leader and trailer tapes 339.2.3 Splicing tape 339.3 Width 339.3.1 Width of magnetic, lea
18、der and trailer tape 339.3.2 Width and position of splicing tape 339.4 Discontinuities 339.5 Thickness 349.5.1 Thickness of magnetic tape 349.5.2 Thickness of leader and trailer tape 349.5.3 Thickness of splice tape 349.6 Longitudinal curvature 349.7 Cupping 349.8 Coating adhesion 34- iii -9.9 Layer
19、-to-layer adhesion 359.10 Tensile strength 359.10.1 Breaking strength 359.10.2 Yield strength 359.11 Residual elongation 359.12 Electrical resistance of the recording surface 369.13 Tape winding 369.14 Light transmittance of tape 369.15 Data cartridge recognition stripe 3610 Magnetic recording chara
20、cteristics 3710.1 Test conditions 3710.2 Typical Field 3710.3 Signal Amplitude 3710.4 Resolution 3710.5 Narrow-band Signal-to-Noise Ratio 3810.6 Ease of erasure 3810.7 Tape quality 3810.7.1 Missing pulses 3810.7.2 Missing pulse zone 3810.7.3 Overwrite 38Section 4 - Requirements for an Interchanged T
21、ape 3911 Format of a track pair 3911.1 General 3911.2 Physical block format 4011.2.1 General 4011.2.2 Common header fields 4111.2.3 Data Block 4211.2.4 Erase Block 4311.2.5 Diagnostic Block 4311.2.6 Physical Beginning of Partition (PBOP) Block 4411.2.7 Long File Mark Block 4411.2.8 Short File Mark B
22、lock 4511.2.9 Logical Beginning of Partition (LBOP) Block 4511.2.10 Set Mark Block 4711.2.11 Gap Block 4711.2.12 End of Data (EOD) Block 4811.2.13 Recorded patterns 4811.3 Search field format 5011.3.1 Search field data 5011.3.2 Search field ECC 5111.3.3 Search field recording patterns 5211.4 Servo a
23、rea 5311.5 Track layout 5412 Method of recording 5512.1 Physical Recording Density 5612.1.1 Long Term Average Bit Cell Length 5612.1.2 Short Term Average Bit Cell Length 5612.1.3 Rate of Change 5612.2 Bit Shift 56- iv -12.3 Amplitude of Data Signals 5613 Track geometry 5613.1 General 5613.2 Average
24、track pitch - C 5713.3 Track pitch variation 5713.4 Track width - B 5713.5 Track angle - A 5713.6 Track length -E 5713.7 Guard band - F 5713.8 Azimuth angles 5713.9 Track linearity 5714 Layout of a tape 5814.1 General 5814.2 Tape History Log (THL) 5814.3 Physical Beginning of Partition 5814.4 Logica
25、l Beginning of Partition 5814.5 Data area 5814.5.1 General 5814.5.2 Short File Mark 5914.5.3 Long File Mark 5914.5.4 Set Mark 5914.6 End of Data 5914.7 Physical End of Partition (PEOP) 59Annex A - Measurement of Light Transmittance of Tape and Leaders 61Annex B - Measurement of bit shift 65Annex C -
26、 Representation of 8-bit bytes by 10-bit patterns 67Annex D - Generation of Data Area CRC 75Annex E - Generation of ECC 77Annex F - Generation of Logical Block CRC 79Annex G - Generation of Hamming Code ECC 81Annex H - Generation of Search Field CRC 83Annex J - Randomization 85Annex K - Recommendati
27、ons for Transportation 87Section 1 - General1ScopeThis ECMA Standard specifies the physical and magnetic characteristics of a 8 mm wide magnetic tapecartridge to enable physical interchange of such cartridges between drives. It also specifies the quality of therecorded signals, the recording method
28、and the recorded format, thereby allowing data interchange betweendrives by means of such magnetic tape cartridges.Information interchange between systems also requires, at a minimum, agreement between the interchangeparties upon the interchange code(s) and the specifications of the structure and la
29、belling of the informationon the interchanged cartridge.2 Conformance2.1 Magnetic tape cartridgesA magnetic tape cartridge shall be in conformance with this ECMA Standard if it satisfies all mandatoryrequirements of this ECMA Standard throughout the extent of the tape.2.2 Generating driveA drive gen
30、erating a magnetic tape cartridge for interchange shall be entitled to claim conformance withthis ECMA Standard if all the recordings that it makes on a tape meet the mandatory requirements of thisECMA Standard. A claim of conformance shall state whether or not one or more registered compressionalgo
31、rithm(s) are implemented within the system to process data from the host prior to allocating data tophysical blocks.2.3 Receiving driveA system receiving a magnetic tape cartridge for interchange shall be entitled to claim conformance withthe ECMA Standard if it is able to handle any recording on th
32、is tape according to this ECMA Standard. Areceiving drive shall be able to recognize the use of a data compression algorithm and make the algorithmregistration number available to the host.3 ReferencesISO 527-1:1993 Plastics - Determination of tensile properties - Part 1: General principles.ISO 1302
33、:1992 Technical Drawings - Method of indicating surface texture on drawings.ISO/IEC 11576:1994 Information technology - Procedure for the registration of algorithms for the losslesscompression of data.ECMA-129 (1994) Information Technology Equipment - Safety4 DefinitionsFor the purpose of this ECMA
34、Standard, the following definitions apply.4.1 a.c. eraseA process of erasure utilizing alternating magnetic fields of decaying intensity.4.2 algorithmA set of rules for transforming the logical representation of data.4.3 append pointThe first physical block on the first track 1 following the two gap
35、 stripes that precede a Long File Mark,Set Mark, or EOD and follow the last track pair containing any portion of a logical block- 2 -4.4 Average Signal AmplitudeThe average peak-to-peak value of the signal of a read head measured over a minimum of 3 000 fluxtransitions, exclusive of missing pulses.4
36、.5 azimuthThe angular deviation, in degrees of arc, of the recorded flux transitions on a track from a line normal tothe track centreline.4.6 back surfaceThe surface of the tape opposite to the magnetic coating used to record data.4.7 bit cellA distance along the track allocated for the recording of
37、 a channel bit.4.8 byteAn ordered set of bits acted upon as a unit.4.9 cartridgeA case containing magnetic tape stored on twin reels.4.10 Channel bitA bit after 8-10 transformation.4.11 ClusterA group of sequential blocks of the same block type.4.12 Cyclic Redundancy Check (CRC) characterA character
38、 derived from information contained in data bytes that are used for error detection.4.13 Digital Sum Variation (DSV)The integrated value of channel bits taken from the beginning of each track counting a ONE as +1 and aZERO as -1.4.14 Error Correcting Code (ECC)A mathematical procedure yielding bytes
39、 used for the detection and correction of errors.4.15 File MarkA mark recorded on the tape at the request of the host system to separate files or to provide a splice point.This format provides for Long or Short File Marks.4.16 flux transition spacingThe distance along a track between successive flux
40、 transitions.4.17 Logical Beginning of Partition (LBOP)The point in a partition where a recording of data for interchange commences.4.18 Logical BlockInformation (data, file marks, or set marks) sent from the host to the tape drive to be recorded.4.19 magnetic tapeA tape that accepts and retains mag
41、netic signals intended for input, output, and storage of data forinformation processing.4.20 Master Standard Reference TapeA tape selected as the standard for Signal Amplitude, Typical Field, Overwrite and Resolution.NOTEThe Master Standard Reference Tape has been established by Pericomp Corporation
42、.- 3 -4.21 PartitionA formatted length of tape used to record data. Partitions are used to divide the tape into shorterupdatable areas.4.22 Physical Beginning of Partition (PBOP)The point along the length of tape at which a partition begins.4.23 Physical Beginning of Tape (PBOT)The transition from t
43、he tape leader to the opaque area of the splice by which the translucent leader tape isjoined to the magnetic tape.4.24 Physical End of Partition (PEOP)The point along the length of tape at which a partition ends.4.25 Physical End of Tape (PEOT)The transition from the opaque area of the splice to th
44、e translucent trailer tape.4.26 physical recording densityThe number of recorded flux transitions per unit length of track, expressed in flux transitions permillimetre (ftpmm).4.27 Read Back Check (RBC)A Read Back Check occurs when, while writing, the data is read by trailing heads and checked for e
45、rrors.4.28 Reference FieldThe Typical Field of the Master Standard Reference Tape.4.29 Secondary Standard Reference Tape (SSRT)A tape the performance of which is known and stated in relation to that of the Master Standard ReferenceTape.NOTESecondary Standard Reference Tapes can be ordered under the
46、Part Number SSRT/M.AME/PC97, fromPericomp Corporation, 14 Huron Drive, Natick, MA 01760, USA.In principle, such tapes will be available for a period of 10 years from the first edition of this ECMAStandard. However, by agreement between ECMA and Pericomp, this period may be shortened orextended to ta
47、ke account of demand for such tapes.It is intended that these be used for calibrating Tertiary Reference Tapes for use in routine calibration.4.30 Set MarkA mark recorded on the tape at the request of the host system to separate a set of data or to provide asplice point.4.31 Standard Reference Ampli
48、tude (SRA)The Average Signal Amplitude derived from the Master Standard Reference Tape, using the TestRecording Current at 3 819 ftpmm.4.32 Standard Reference Current (Ir)The current that produces the Reference Field.4.33 Tape Reference EdgeThe lower edge of tape as seen when viewing the recording s
49、urface of the tape with the supply reel to theobservers right.4.34 Test Recording Current (TRC)The current used to record the SRA. The TRC is 1,5 times the Standard Reference Current.- 4 -4.35 TrackA diagonally positioned area on the tape along which a series of magnetic transitions may be recorded.4.36 Typical FieldIn the plot of the Average Signal Amplitude against the recording field at the physical recording density of3 819 ftpmm, the minimum field that causes an Average Signal Amplitude equal to 90% of the maximumAverage Signal Amplitude.5 Conventions and Notations5.1 Representati
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