1、ANSI INCITS 243-1996 (R2001)(formerly ANSI X3.243-1996 (R2001)for Information Technology Recorded Magnetic Tape Cartridgefor Information Interchange Serial, 0.250 inch (6.35 mm), 26-Track,16 000 bpi (630 bpmm), StreamingMode, Group Code RecordingAmerican National Standardfor Information Technology R
2、ecorded Magnetic Tape Cartridge for Information Interchange Serial, 0.250 inch (6.35 mm), 26-Track, 16 000 bpi (630 bpmm), Streaming Mode, Group Code RecordingApproved June 5, 1996American National Standards Institute, Inc.ANSIX3.243-1996SecretariatInformation Technology Industry CouncilAmericanNati
3、onalStandardApproval of 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 agre
4、ement has been reached 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 Americ
5、an National Standards 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 In
6、stitute does not develop 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 f
7、or interpretations should 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 pe
8、riodically to reaffirm, revise, or withdrawthis standard. Purchasers of American National Standards may receive currentinformation on all standards by calling or writing the American National StandardsInstitute.CAUTION: The developers of this standard have requested that holders of patents that may
9、be required for theimplementation of the standard disclose such patents to the publisher. However, neither the developers nor the publisherhave undertaken a patent search in order to identify which, if any, patents may apply to this standard. As of the date ofpublication of this standard and followi
10、ng calls for the identification of patents that may be required for the implementationof the standard, no such claims have been made. No further patent search is conducted by the developer or publisher inrespect to any standard it processes. No representation is made or implied that licenses are not
11、 required to avoidinfringement in the use of this standard.Published byAmerican National Standards Institute11 West 42nd Street, New York, New York 10036Copyright 1996 by Information Technology Industry Council (ITI)All rights reserved.No part of this publication may be reproduced in anyform, in an
12、electronic retrieval system or otherwise,without prior written permission of ITI, 1250 Eye Street NW,Washington, DC 20005.Printed in the United States of AmericaiForeword.iii1 Scope and purpose 12 Normative references .23 Definitions24 Track geometry 45 Recording 76 Use of tracks97 Byte and code req
13、uirements .118 Transforming of coded characters.119 Track format.1210 Error correction 29Tables1 Track positions.62 Encoding table .123 Inquiry data format .154 Header list165 Block descriptor list 176 Page descriptor list.177 Encoding of block type control bits218 Example of codewords31Figures1 Tra
14、ck locations.52 Rate of change test pattern 83 Test pattern for instantaneous flux84 Requirements for use of tracks .105 General track layout .126 General frame layout 137 Layout of block 0 in ID frame 148 Layout of first 8 bytes of block 0 in ID frame149 Layout of identifier block 21610 Layout of i
15、dentifier block 51711 Layout of a block 1812 Layout of control field .1913 Layout of control byte 3 20ContentsPageii14 Layout of control field, bytes 02 2015 Examples of possible format layout variations due to block rewrite operations2316 Layout of data field, physical variable data blocks .2317 Va
16、riable host block, 4096 data bytes.2418 Variable host block, 2051 data bytes.2419 Variable host block, 1673 data bytes.2520 Postamble/preamble overlap during append operations.2521 Data compression, fixed blocks.2722 Data compression, variable blocks2823 Layout of byte 14, mode select/sense .2824 EC
17、C frame format.3025 Bit numbering convention .30AnnexesA Cancel mark option.32B Reading identifier block information 35PageiiiThis standard presents the minimum requirements for the organization andlocation of magnetically encoded data on a 0.250 inch (6.35 mm) widemagnetic tape cartridge to allow p
18、arties that comply with these require-ments to interchange information reliably. The standard applies to 26-track, 16 000 bpi (630 bpmm), serial, group coded information using tapedrives that operate in the streaming mode.The advantage of using the format described in this standard is that it pro-vi
19、des for more than double the data capacity, and, due to the inclusion of apowerful error correction capability, a substantially increased data reliabili-ty, when compared to the cartridge described in American NationalStandard for Information Systems Serial Recorded Magnetic Tape Cartridgefor Inform
20、ation Interchange 15 and 18 Track, 0.250-inch (6.35-mm), 10 000bpi (364 bpmm) Streaming Mode, Group Code Recording, ANSI X3.204-1992.The impetus to develop this standard was the requirement for highercapacity tape drives to provide backup for the increasingly greater capaci-ties of the fixed media d
21、isk drives being used with information processingsystems.This standard was developed by Technical Committee X3B5 on DigitalMagnetic Tape. This group consists of experienced and qualified special-ists on the recording of digital information on magnetic tape. In the devel-opment of this standard, care
22、ful consideration was given to current prac-tices, existing equipment and supplies, achieving the broadest possibleacceptance, and providing a basis for future improvement in the use of themedium.This standard contains two annexes. Annex A is normative and is consid-ered a part of this standard. Ann
23、ex B is informative and is not consideredpart of 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.This standard was p
24、rocessed 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 had the following mem
25、bers: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 Kellenbenz (Alt.)Foreword
26、(This foreword is not part of American National Standard X3.243-1996.)ivATb) 10 000 ftpi (394 ftpmm);c) 6667 ftpi (262 ftpmm).5.3 Average transition-cell length variations5.3.1 Average transition-cell lengthThe average transition-cell length is the sum of the distances between the flux transitions i
27、n n tran-sition cells divided by (n 1). The tests referred to below may be made in any continuously record-ed pattern, provided the first and the last transition cell in the pattern each contain a flux transition.5.3.2 Long-term average transition-cell lengthThe long-term average transition-cell len
28、gth is the average bit-cell length taken over a minimumof 2 000 000 transition cells. The long-term average transition-cell length shall be within 3% ofthe nominal bit-cell length.5.3.3 Short-term average transition-cell lengthThe short-term average transition-cell length is the average transition c
29、ell-length taken over a mini-mum of 24 transition cells and a maximum of 32 transition cells. The short-term average transition-cell length shall be within 6% of the long-term average transition-cell length.5.3.4 Rate of change of transition-cell lengthThe rate of change of the transition-cell lengt
30、h shall not exceed 0.25%. The rate of change isgiven by the following relationship:Rate of change = 0.25%100 |t1/4 t2/4|t3/57where t1, t2, and t3are the times between flux transitions as shown in figure 2.Periods 1 through 5 are contiguous and represent the repetitive encoding pattern 1010102withina
31、 data block, and frequency variations are less than 20 kHz.5.3.5 Instantaneous flux transition spacingThe instantaneous spacing between flux transitions is influenced by the reading and writing pro-cess, the pattern recorded (pulse-crowding effect) and other factors. Instantaneous spacingsbetween fl
32、ux transitions shall satisfy the following conditions:In a sequence of flux transitions defined by the encoded pattern 111001112, the center fluxtransition of each group of 1s is called a reference flux transition. The maximum displacementof flux transitions on either side of the reference flux tran
33、sitions shall not exceed 28% of thetransition cell length d1 averaged over the five transition cells between the reference flux tran-sitions indicated in the bit pattern in figure 3.5.4 Signal amplitudeThe signal amplitude shall be measured at a point in the read channel where the signal is propor-t
34、ional to the voltage generated by the read head.5.4.1 Average signal amplitude at nominal maximum densityAt the nominal maximum physical recording density 20 000 ftpi (787 ftpmm), the average peak-to-peak signal amplitude of the interchange tape shall deviate by no more than + 50% or 35% from the st
35、andard reference amplitude. This averaging shall be made over thecentral 100 flux transitions of any 120 or more flux transitions recorded at nominal maximum den-sity in a block and over at least 200 blocks. Traceability to the standard reference amplitude isprovided by the calibration factors suppl
36、ied with each secondary standard reference tape.ANSI X3.243-199681 1 1 0 0 1 1 1Td d d d Where:d1 = T/5d1(1 0.28) d d 1(1 + 0.28)X denotes a reference flux transition.Figure 3 Test pattern for instantaneous fluxFigure 2 Rate of change test pattern1 0 1 0 1 0 1 0 1 0 1t1t2t3ANSI X3.243-19965.4.2 Maxi
37、mum signal amplitudeWithin the valid information area there shall not be any flux transitions where the peak-to-peaksignal amplitude is more than three times the standard reference amplitude at 20 000 ftpi (787 ftpmm).5.5 Recorded azimuthOn any track the angle that a flux transition across the track
38、 makes with a line perpendicular tothe reference edge of the tape shall not exceed 7 minutes of arc (2.04 mrad).5.6 ErasureThe magnetic tape shall be ac-erased prior to recording such that after the erasure any remainingsignal amplitudes below twice the frequency corresponding to the maximum physica
39、l recordingdensity shall be less than 3% of the standard reference amplitude at 20 000 ftpi (787 ftpmm).When terminating a write operation on track 0, a minimum distance of 45 in (1143 mm) shall beerased after the end of the recorded area. The whole distance between the end of the recorded areaand t
40、he first EOT hole shall be erased if this distance is less than 45 in (1143 mm).6 Use of tracks6.1 Data tracksEach track shall be a data track and shall be written sequentially, one track at a time, in ascend-ing numerical order.6.2 Track numberingAll even-numbered tracks shall be recorded in the fo
41、rward direction (the direction from the BOTmarker to the EOT marker). All odd-numbered tracks shall be recorded in the reverse direction(the direction from the EOT marker to the BOT marker). If the quick file access (QFA) option isimplemented, track 25 shall be recorded in the forward direction.6.3
42、Forward reference bursts (see figure 4)On tracks 0, 2, 4, 6, 8, and 10, a forward reference burst shall be recorded at the beginning ofeach of these tracks. The reference burst on track 0 shall be recorded using a physical recordingdensity of 10 000 ftpi (394 ftpmm), while the other reference bursts
43、 shall be recorded using aphysical recording density of 20 000 ftpi (787 ftpmm). When recorded in the forward direction(QFA implemented) track 25 shall also be recorded with a reference burst as shown in figure 4.These forward reference bursts shall be written between the BOT marker and the beginnin
44、g of therecorded data area of the track. The reference burst shall start a minimum of 0 in (0 mm) and amaximum of 15 in (381 mm) from the BOT marker, and shall extend past the LP marker for a min-imum of 3 in (76 mm) and a maximum of 4 in (101 mm). There shall be no erased area betweenthe end of the
45、 forward reference burst and the beginning of the preamble for the first data blockon each of these tracks. Except for the forward reference bursts, there shall be no recorded sig-nals between the BOT and the LP marker on the lower half of the tape.6.4 Reverse reference bursts (see figure 4)On track
46、s 1, 3, 5, 7, 9, and 11, a reverse reference burst shall be recorded at the beginning ofeach of these tracks. The reverse reference burst on track 1 shall be recorded using a physicalrecording density of 10 000 ftpi (394 ftpmm), while the other reference bursts shall be recorded usinga physical reco
47、rding density of 20 000 ftpi (787 ftpmm).These reverse reference bursts shall be writ-ten between the EOT marker and the beginning of the recorded data area on each of thesetracks. These reference bursts shall start a minimum of 0 in (0 mm) and a maximum of 15 in (381mm) from the EOT marker, and sha
48、ll extend past the EW marker for a minimum of 3 in (76 mm)and a maximum of 4 in (101 mm). There shall be no erased area between the end of the reversereference bursts and the beginning of the preamble for the first data block on each track. The9ANSI X3.243-199610Minimum MaximumDimension in mm in mm
49、DescriptionD1 0 0 15 381 BOT or EOT to start of reference burstD2 3 101 4 101LP or EW to start of valid data (or frame) area plus LP/EW toend of reference burst on tracks with reference burstD3 36 914 EW to end of data on even tracksD4 27 686LP to end of data on all odd tracks except tracks 1, 2, 5, 13,15, and 19D5 0.1 2.5 4 101 End of data to LP on tracks 1, 3, 5, 13, 15, and 19Figure 4 Requirements for use of tracksANSI X3.243-1996reverse reference bursts for tracks 1, 3, and 5 will cross over the EW hole and
