1、Standard ECMA-2482ndEdition - June 1998Standardizing Information and Communication SystemsPhone: +41 22 849.60.00 - Fax: +41 22 849.60.01 - URL: http:/www.ecma.ch - Internet: helpdeskecma.ch12,65 mm Wide Magnetic TapeCassette for InformationInterchange - Helical ScanRecording - DTF-1 Format.Standard
2、 ECMA-2482ndEdition - June 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-248-ii.doc 02-07-98 15,5412,65 mm Wide Magnetic TapeCassette for InformationInterchange - Helical ScanRecording -
3、 DTF-1 Format.Brief HistoryECMA has produced a series of Standards for cassettes and cartridges containing magnetic tapes of different widthsand characteristics.ECMA Standards for cartridges recorded in a linear mode are:ECMA-120 (1993) : Data Interchange on 12,7 mm 18-Track Magnetic Tape Cartridges
4、ECMA-152 (1993) : Data Interchange on 12,7 mm 18-Track Magnetic Tape Cartridges - Extended FormatECMA-182 (1992) : Data Interchange on 12,7 mm 48-Track Magnetic Tape Cartridges - DLT 1 FormatECMA-196 (1993) : Data Interchange on 12,7 mm 36-Track Magnetic Tape CartridgesECMA-197 (1993) : Data Interch
5、ange on 12,7 mm 112-Track Magnetic Tape Cartridges - DLT 2 FormatECMA-209 (1994) : Data Interchange on 12,7 mm 128-Track Magnetic Tape Cartridges - DLT 3 FormatECMA-231 (1995) : Data Interchange on 12,7 mm 128-Track Magnetic Tape Cartridges - DLT 4 FormatECMA Standards for cartridges recorded in a h
6、elical mode are:ECMA-139(1990): 3,81 mm Wide Magnetic Tape Cartridges - Helical Scan Recording - 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
7、ScanRecording - DATA/DAT FormatECMA-150(1992): 3,81 mm Wide Magnetic Tape Cartridge for Information Interchange - Helical ScanRecording - DDS-DC FormatECMA-169(1992): 8 mm Wide Magnetic Tape Cartridge, Dual Azimuth for Information Interchange - HelicalScan RecordingECMA-170(1992): 3,81 mm Wide Magne
8、tic Tape Cartridge for Information Interchange - Helical ScanRecording - DDS Format using 60 m and 90 m Length TapesECMA-171(1992): 3,81 mm Wide Magnetic Tape Cartridge for Information Interchange - Helical ScanRecording - DATA/DAT-DC Format using 60 m and 90 m Length TapesECMA-198(1995): 3,81 mm Wi
9、de Magnetic Tape Cartridge for Information Interchange - Helical ScanRecording - DDS-2 Format using 120 m Length TapesECMA-210(1995): 12,65 mm Wide Magnetic Tape Cartridge for Information Interchange - Helical ScanRecording - DATA-D3-1 FormatECMA-236(1996): 3,81 mm Wide Magnetic Tape Cartridge for I
10、nformation Interchange - Helical ScanRecording - DDS-3 Format using 125 m Length TapesThis Standard ECMA-248 describes a cassette containing magnetic tape 12,65 mm wide. The processing of data andmethod of recording employ technologies developed for recording digital television signals and thus prov
11、ide highcapacity and data rate. Furthermore, the directory and file structure placeholders defined in this ECMA Standardprovide for fast search and access to very large sets of data recorded on this magnetic tape as well as providing fordisaster recovery in the case of a lost or destroyed directory.
12、 Two types of cassette are defined, containing tapes ofdifferent lengths.This Standard has been adopted as 2ndedition of ECMA-248 by the ECMA General Assembly of June 1998.- i -Table of contentsSection 1 - General 11 Scope 12 Conformance 12.1 Magnetic tape cassette 12.2 Generating system 12.3 Receiv
13、ing system 13 References 14 Definitions 14.1 Absolute block number 24.2 a.c. erase 24.3 algorithm 24.4 Append file 24.5 Append volume 24.6 Average Signal Amplitude (ASA) 24.7 azimuth 24.8 back surface 24.9 bit cell 24.10 block 24.11 Block Management Table (BMT) 24.12 byte 24.13 cassette 24.14 compre
14、ssed data 24.15 Control Track 24.16 flux transition position 24.17 flux transition spacing 24.18 Logical track set ID 24.19 Logical volume 34.20 magnetic tape 34.21 Master Standard Reference Tape (MSRT) 34.22 physical recording density 34.23 Reference Field (RF) 34.24 Secondary Standard Reference Ta
15、pe (SSRT) 34.25 Standard Reference Amplitude (SRA) 34.26 Standard Reference Current (Ir) 34.27 Tape Reference Edge 34.28 Test Recording Current (TRC) 34.29 track 44.30 track angle 44.31 Track Set 44.32 Typical Field (TF) 44.33 Unique Identifier (UID) 44.34 word 45 Conventions and notations 45.1 Repr
16、esentation of numbers 45.2 Names 46 Acronyms 4- ii -7 Environment and safety 57.1 Testing environment 57.2 Operating environment 57.3 Storage environment 57.4 Transportation 67.5 Safety 67.6 Flammability 6Section 2 - Requirements for the case 68 Dimensional and mechanical characteristics of the case
17、 68.1 General 68.2 Type S cassette 68.2.1 Overall dimensions 78.2.2 Holding areas 78.2.3 Window 78.2.4 Label areas (figure 4) 88.2.5 Datum areas and datum holes 88.2.6 Support areas 88.2.7 Guiding grooves 98.2.8 Recognition holes 108.2.9 Write-inhibit plug 128.2.10 Pre-positioning surface 128.2.11 C
18、assette lid 138.2.12 Cassette reel lock 148.2.13 Reel access holes 148.2.14 Reels 148.2.15 Position of the tape in the case 158.2.16 Tape path zone 158.2.17 Tape access cavity 168.3 Type L cassette 318.3.1 Overall dimensions 318.3.2 Holding areas 318.3.3 Window 328.3.4 Label areas 328.3.5 Datum area
19、s and datum holes 328.3.6 Support areas 338.3.7 Guiding grooves 338.3.8 Recognition holes 348.3.9 Write-inhibit plug 358.3.10 Pre-positioning surface 368.3.11 Cassette lid 368.3.12 Cassette reel lock 378.3.13 Reel access holes 378.3.14 Reels 388.3.15 Position of the tape in the case 398.3.16 Tape pa
20、th zone 398.3.17 Tape access cavity 408.3.18 Cavity for compatibility with Type S cassette 41Section 3 - Requirements for the unrecorded tape 579 Mechanical, physical and dimensional characteristics of the tape 579.1 Materials 579.2 Tape length 57- iii -9.3 Tape width 579.4 Width and position of spl
21、icing tape 579.5 Discontinuity 579.6 Tape thickness 579.7 Longitudinal curvature 579.8 Out-of-plane distortions 589.9 Coating adhesion 589.10 Layer-to-layer adhesion 589.11 Tensile strength 599.11.1 Breaking strength 599.11.2 Yield strength 599.11.3 Strength of Splice 599.12 Residual elongation 599.
22、13 Electrical resistance of the coated surfaces 599.14 Tape wind 6010 Magnetic recording characteristics 6010.1 Typical Field TF1 6010.2 Average Signal Amplitude(ASA) 6010.3 Resolution 6010.4 Signal-to-noise ratio (S/N) 6110.5 Ease of erasure 6110.6 Tape quality 6110.6.1 Missing pulses 6110.6.2 Miss
23、ing pulse zone 6110.7 Inhibitor tape 61Section 4 - Requirements for an interchanged tape 6211 Format for helical tracks 6211.1 General description of the write data path (see figure 42) 6211.2 Formation of a Logical Track Set 6211.2.1 Types of information track sets 6211.2.2 Generation of a Logical
24、Track Set 6411.2.3 Subcode data field 6611.2.4 BMT 6711.2.5 Data and information field definitions 6811.3 Track Set information 7211.3.1 Loading the Product Code Arrays 7211.4 Product code array processing 7411.4.1 Error correction method 7411.4.2 Error correction coding for C1 Parity 7411.5 Track a
25、ssignments 7611.5.1 Sectors 7611.5.2 Sync Blocks 7611.5.3 Track interleave 7711.5.4 Track Sync Blocks 7811.5.5 Byte interleave across Sync Blocks 7911.5.6 Randomization 8011.6 Formation of the contents of a helical track 8011.6.1 Sector details 8011.7 Channel bit coding 82- iv -11.7.1 General 8211.7
26、.2 Interleaved-NRZ1 8212 Track geometry 8212.1 General 8212.2 Helically recorded tracks 8212.2.1 Location of the tracks 8212.2.2 Track width 8312.2.3 Track angle 8312.2.4 Track pitch 8312.2.5 Location of elements in the helical track 8412.2.6 Location of the Data Area Reference Point 8412.2.7 Straig
27、htness of tracks 8412.2.8 Azimuth angles 8412.2.9 Tracking Pilot Signal (TPS) 8412.2.10 Amplitude of servo signals 8412.3 Longitudinal tracks geometry 8512.3.1 Control Track 8512.3.2 Time Code Track signals recording position 8513 Method of recording helical tracks 8513.1 Physical recording density
28、8513.2 Record current optimization 8513.3 Efficiency of erasure 8514 Method of recording longitudinal tracks 8514.1 Overview 8514.2 Control Track 8514.2.1 Signal 8514.2.2 Polarity of magnetisation 8614.2.3 Alignment 8614.2.4 Read signal amplitude 8614.2.5 Quality of the Control Track 8614.3 Time Cod
29、e Track 8614.3.1 Method of recording the Time Code Track 8614.3.2 Physical recording density 8714.3.3 Bit shift 8714.3.4 Read signal amplitude 8714.3.5 Quality of the Time Code Track 8714.4 Format for the Time Code Track 8714.4.1 Count bits 8714.4.2 Phase bit 8714.4.3 Synchronizing pattern 8714.4.4
30、Supplemental Data 8714.4.5 Extent of Time Code 87Section 5 - Requirements for recorded information 8815 Recorded information 8815.1 Recording area 8815.2 Magnetic tape layout 8815.2.1 Valid data areas 8815.2.2 Invalid data areas 88- v -15.3 Physical TSID 8915.3.1 Structure surrounding the VSIT area
31、9015.3.2 Structure of the DIT area 9015.3.3 Structure of the User Data Area 91Section 6 - Write operations 9216 Write retry sequence 9217 Append file operation 9217.1 Append volume 9217.2 Append write 9317.3 Overwrite 9317.4 File extension 94Annex A - Measurement of Signal-to-Noise Ratio 97Annex B -
32、 Representation 8/9 coding patterns 99Annex C - Recommendations for Transportation 103Annex D - Inhibitor Tape 105- vi -.Section 1 - General1ScopeThis ECMA Standard specifies the physical and magnetic characteristics of magnetic tape cassettes, usingmagnetic tape 12,65 mm wide so as to provide physi
33、cal interchange of such cassettes between drives. It alsospecifies the quality of the recorded signals, the recording method and the recorded format, called DigitalTape Format-1 (DTF-1), thereby allowing data interchange between drives by means of such cassettes. Theformat supports variable length L
34、ogical Records, high speed search, and the use of a registered algorithm fordata compression.This ECMA Standard specifies two sizes of cassette. For the purposes of this ECMA Standard the largercassette is referred to as Type L, and the smaller as Type S.Together with a standard for volume and file
35、structure, e.g. Standard ECMA-13, this ECMA Standardprovides for full data interchange between data processing systems.2 Conformance2.1 Magnetic tape cassetteA claim of conformance with this ECMA Standard shall specify the Type of cassette. It shall be inconformance with this ECMA Standard ifG01 the
36、 case meets all the requirements of clause 4 and clauses 6 to 10 for that TypeG01 the recording on the tape meets the requirements of clauses 11 to 172.2 Generating systemA claim of conformance with this ECMA Standard shall specify which Type(s) of cassette is (are)supported. A system generating a m
37、agnetic tape cassette for interchange shall be in conformance with thisECMA Standard if all the recordings that it makes, meet the mandatory requirements of this ECMAStandard. A claim of conformance with this ECMA Standard shall state whether or not one, or more,registered algorithm(s) is (are) impl
38、emented and, if so, the registered number(s) of (all) the implementedalgorithm(s).2.3 Receiving systemA claim of conformance with this ECMA Standard shall specify which Type(s) of cassette is (are)supported. A system receiving a magnetic tape cassette for interchange shall be in conformance with thi
39、sECMA Standard if it is able to handle any recording made on the tape according to this ECMA Standard,and a claim of conformance shall state whether or not one, or more, registered algorithm(s) is (are)implemented and, if so, the registered number(s) of (all) the implemented algorithm(s).3 Reference
40、sECMA-13: 1985 File structure and Labelling of Magnetic Tapes for Information InterchangeECMA-129: 1994 Information Technology Equipment - SafetyISO/R527:1966 Plastics Determination of tensile propertiesISO/IEC 11576:1994 Information Technology - Procedure for the Registration of Algorithms for theL
41、ossless Compression of DataSMPTE timecode: (C98.12 : time and control code for video and audio tape for 525/60 televisionsystem)JIS-B-7502 Characteristics of plastic goods4 DefinitionsFor the purpose of this ECMA Standard, the following definitions apply.- 2 -4.1 Absolute block numberA number N allo
42、cated to each block, indicating that the block is the Nth block from the beginning of theLogical volume containing it.4.2 a.c. eraseA process of erasure utilizing alternating magnetic fields of decaying intensity.4.3 algorithmA set of rules for transforming the logical representation of data.4.4 App
43、end fileA new file added from the End of Data (EOD) of a Logical volume.4.5 Append volumeA Logical volume added after the last Logical volume recorded on the cassette.4.6 Average Signal Amplitude (ASA)The average peak-to-peak value of the signal output of a read head measured over a minimum of 1,40
44、mmof track, exclusive of missing pulses.4.7 azimuthThe angular deviation, in degrees of arc, of the recorded flux transitions on a track from the line normal tothe track centreline.4.8 back surfaceThe surface of the tape opposite to the magnetic coating used to record data.4.9 bit cellA distance alo
45、ng the track allocated for the recording of a Channel bit.4.10 blockA unit of data which is sent to the tape controller when a single write command is executed.4.11 Block Management Table (BMT)A table included in each Track Set to manage blocks contained in that Track Set.4.12 byteAn ordered set of
46、bits acted upon as a unit.4.13 cassetteA case containing magnetic tape stored on twin reels.4.14 compressed dataA representation of host-transmitted data after transformation by a data compression algorithm.4.15 Control TrackA track used for recording the servo control signals.4.16 flux transition p
47、ositionThat point along a track on the magnetic tape that exhibits the maximum free-space flux density normal tothe tape surface.4.17 flux transition spacingThe distance along a track between successive flux transitions.4.18 Logical track set IDThe track set ID assigned to each track set containing
48、data received from the host.- 3 -4.19 Logical volumeA data entity received by the generating system from the host.4.20 magnetic tapeA tape which will accept and retain the magnetic signals intended for input, output, and storage purposes.4.21 Master Standard Reference Tape (MSRT)A tape selected as t
49、he standard for Signal Amplitude, Reference Field, Resolution and Signal to NoiseRatio (S/N).NOTEThe Master Standard Reference Tape has been established at SONY Corporation.4.22 physical recording densityThe number of recorded flux transitions per unit length of track, specified as flux transitions permillimetre (ftpmm).4.23 Reference Field (RF)The Typical Field of the MSRT. There are two Reference Fields:RF1 is that for a helically recorded trackRF2 is that for a longitudinally recorded track.4.24 Secondary Standard Reference Tape (SSRT)A tape the performance of which is known and stat
