CA1066406A - Magnetic record member for use with rotating head magnetic recording apparatus - Google Patents

Abstract

MAGNETIC RECORD MEMBER FOR USE WITH ROTATING
HEAD MAGNETIC RECORDING APPARATUS
Abstract An elongated magnetic tape has a pair of longitudinally extending servo track areas, one of which is closer to the longitudinal center of the tape than the other. The lateral space intermediate the servo areas receives data signals, while the space between said one servo area and one edge contains identification and address signals. The tape is par-ticularly adapted for use with rotating head recorders having two gaps on the rotor, with an intergap distance slightly greater than the lateral extent of the servo areas. A recording or write gap precedes an immediately trailing reading or recovery gap. When the rotor gaps pass the one edge in the one servo area, the write gap senses the servo track; while the read gap senses the identification signals. The arrangement is such that prior to the time the write gap reaches the data recording area, the read gap has sensed the identifi-cation signals. In a similar manner, when the gaps are leaving the data signal area, the write gap is sensing the other servo area; while the read gap is still sensing data. The longitudinal extent of the servo areas indicates, respectively, beginning of tape (BOT) and end of tape (EOT). A leader portion includes a magnetic coating for facilitating calibrating magne-tic recording apparatus to each particular article.

Description

~066406 1 Background of the Invention

2 The present invention relates to an improved

3 magnetic medium particularly adapted for use with ro-

4 tating head magnetic recorders, also referxed to as "transverse" magnetic recorders.
6 Rotating head recorders have been used for 7 the last several years for recording video or televi-8 sion signals. Such signals are analog in character g which permits repeated signal usage to compensate for defective recording, while not materially detracting 11 from the quality of the television picture presented 12 on a television set or CRT screen.
13 Such video recorders employ carrier recording 14 techniques with the carrier at the upper portion of the frequency band of the signals being recorded. Such 16 video recorders have been employed for digital data 17 recording by modulating digital data signals on the 18 normal video carrier. In contradistinction, most other 19 digital data recorders employ baseband recording rather than heterodyne the information-bearing signals on 21 a carrier.
22 Another aspect of digital data signal recording 23 is that any error conditions cannot be obviated in 24 the same manner as video recording signals can submerge or enable errors to be ignored. In data recording, all 26 signals read back from a record medium must be correct.
27 Further, tape motions employed with digital signal 28 recorders and that of video recorders are quite different.

10664~06 1 Requirements of a digital signal record medium usually 2 require that the magnetic recorder should be able to 3 step the medium to any selected position along its 4 longitudinal length and then precisely indicate to controlling apparatus that the medium is at the desired 6 location. In one form of digital signal data recorders 7 employing rotating heads, during the recording, the 8 magnetic medium is completely stopped; i.e., the appa--9 ratus operates on a step-by~step or incremental mode.
That is, one record stripe is recorded while the tape 11 is stopped. The tape moves to the next stripe with 12 additional data being recorded, etc. Accordingly, 13 any article to be employed with digital data recorders 14 should be capable of being operated efficiently in a step-by-step or incremental mode, as well as in a 16 continuous motion or slewing mode.
17 The history of digital data recording on 18 magnetic tape media indicates that as the technology 19 advances there is a great desire on the part of users that there be backward compatibility. The term "back-21 ward compatibility" means that all newly designed digital 22 data recorders have a capability of reading all previous 23 digital data formats. For example, in the 1/2" tape 24 area, digital data recorders employing 1,600 cpi phase-encoded recording also usually ha~e the capability of 26 reading the prior 800, 556, and 200 cpi NRZI recording.
27 Accordingly, any improved article for use with rotating 28 head digital data recorders should facilitate this so-29 called backward compatibility.

BO973039 ~3~

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~066406 1 Summary of the Invention 2 It is an object of the present invention 3 to provide an improved article for a digital data bearing 4 signal, particularly a magnetic article for recording such signals.
In accordance with the invention, an elongated 7 magnetically coated member has a pair of spaced-apart, 8 longitudinally extending, servo areas adapted to receive 9 digital data signals laterally extending therebetween.
One of the servo areas is spaced from one longitudinal 11 edge of the tape for receiving identification or address 12 signals relatable to the data signals recorded between 13 the servo areas. Further, the servo areas extend lon-14 gitudinally to an extent demarking beginning of tape toward the leader end of the article and end of tape, 16 which denotes the spool end of the article.
17 Further, at the BOT end of the article, a 18 space between the servo areas is reserved for density 19 and format indicating signals for facilitating backward compatibility of recorders employing the improved arti-21 cle. One of the first data stripes adjacent the BOT
22 end of the article includes the serial number of the 23 article. Such serial number is also printed at the free 24 end of the leader extending from the ~OT area. A magne-tically coated portion is reserved for recorder cali-26 bration; that is, whenever the article is loaded onto 27 a rotating head magnetic recording apparatus, that 28 apparatus will record signals in the test area and BO973039 ~4~

1 read such recorded signals back for calibrating the 2 recording apparatus to the readback signals.
3 In a preferred constructed embodiment of 4 the invention, the data stripe angle with respect to the longitudinal edge is about 17-1/2. The distance 6 between two gaps of a magnetic head on a rotor adapted 7 to be employed with the present article has an intergap 8 distance slightly greater than the 17-1/2 angled width 9 of the servo areas. It is preferred that such recorder will employ the leading gap as a recording gap, but 11 switch such gap between readback and recording circuits 12 such that the recording gap can sense the servo track 13 area signals simultaneous to the read gap, reading 14 the identification signals adjacent the one longitudinal edge of the article. This action facilitates switching 16 and stepping of the article. As the write gap leaves 17 the tape immediately adjacent one of the servo signal 18 areas, the read gap is still reading the data area;
19 then, the tape can be simultaneously advanced to the next stripe. A preferred arrangement is such that 21 the periodicity of the rotor and the transit time be-22 tween two adjacent data signal receiving stripes pq~-23 mits the write gap and the read gap to simultaneously 24 read such one servo track area and said identification signals during that portion of the latency period rc-26 quired to step the article.
27 In accordance with another aspcct of the 28 invention, the gaps are switched in accordance with BO973039 ~5~

1()66~06 1 tachometer settings of the magnetic recorder for switching the write gap between recording and readback operations.
3 The foregoing and other objects, features, 4 and advantages of the invention will become apparent from the following more particular description of the 6 preferred embodiment, as illustrated in the accompanying 7 drawing.
8 The Drawing 9 FIGURE 1 is a diagrammatic showing of an improved article constructed in accordance with the 11 present invention.
12 FIGURE 2 is a diagrammatic showing of a pair 13 of data signal receiving stripes, together with the 14 servo signal areas and identification areas. Relation-ship of the geometry to intergap distance of a rotor 16 is illustrated.
17 FIGURE 3 is a greatly enlarged diagrammatic 18 showing of the relationship of the servo track area, 19 identification area, and a signal envelope derived from the improved article by a rotating magnetic trans-21 ducer.
22 FIGURE 4 is a diagrammatic showing of a ro-23 tating head recording apparatus adapted to utilize 24 the present inventive article.
Detailed Description 26 Referring to the drawing, likc numcral.s indi-27 cate like parts and structural features in the various 28 views and diagrams. The improved article of thc prcscnt lOG6406 1 invention is advantageously mounted on a single flange 2 spool 10. A cylindrical sleeve (not shown) fits on 3 the spool to complete a dust-proof enclosure for the 4 record article. The improved article includes elon-gated member 11 having a magnetic coating on one face 6 thereof. The free end of member 11 is tapered at 12 7 for facilitating automatic threading. In the free-8 end portion, as at 13, a plurality of imprinted arti-9 cle serial numbers reside on the coated side of the article. The imprinted serial numbers are viewable 11 through a covering transparent cylindrical sleeve (not 12 shown). Such printing enables visual inspection and 13 identification of various improved articles for faci-14 litating handling and transfer. Such serial numbers facilitate logging performance statistics about each 16 of the articles, as well as facilitating identification.
17 Immediately adjacent free end 12 is a leader 18 area 14 which may or may not have magnetic coating 19 thereon. Leader 14 facilitates automatic threading operations. Immediately adjacent area 14 is a magne-21 tically coated test area 15 for enabling recording 22 and readback of signals by each digital signal recorder 23 employing the improved article. A test pattern of 24 signals recorded in area 15 is sensed by the digital signal recorder. The amplitude, phase shift, and other 26 characteristics of the readback signal are analyzed 27 by recorder circuits which then automatically adjust 28 the readback circuits for optimum readback of data BO973039 ~7~

1(~66406 ; signals recorded on the improved article. The details of such automatic readback circuits are not a part of 3 the present invention.
4 The data recording area 16 of the improved article is completely defined and located by a pair , 6 of servo track areas 17 and 18. Each servo track area 7 in a constructed embodiment of the improved article 8 included areas for two parallel longitudinally extend-9 ing servo tracks. The servo tracks contain signals identifying data stripe locations indicated by dashed 11 lines 20 in FIGURE 1 and by long narrow rectangles 12 21 and 22 in FIGURE 2.
13 Each of the servo tracks in areas 17 and 14 19 may be constructed in accordance with U. S. Patent 3,691,543, no limitation thereto intended. In the 16 alternative, a single servo track may be employed in 17 each of the areas 17 and 19.
18 The servo track areas 17 and 19 have precise 19 longitudinal extents and locations. These areas demark all recording areas on the tape. The servo area ends , 21 adjacent free end 12 define beginning of tape, labeled 22 "BOT", which signifies the area in which a rotating 23 head can start recording data signals. In a similar 24 manner, the spool ends of servo track areas 17 and 19 precisely denote end of the tape, labeled "EOT", 26 which correspondingly defines the other longitudinal 27 limit in which a recorder may record data signals.
28 In addition to data signal rcceiving area 29 16, which is left blank when the improved articlc is . . ~

1 first manufactured, an identification and addressing 2 track is located at 25 with a longitudinal extent sub-3 stantially longitudinally coextensive with servo area 4 19. Identification and addressing area 25 will be described in detail later. In an early constructed 6 embodiment of the present improved article, the iden-7 tification area ended at 26 longitudinally toward spool 8 10 from free end 12. The first data record area number g was 0 identifying a so-called "stripe 0". In this first constructed embodiment, stripe 0 had recorded 11 therein the serial number of the improved article, 12 which serial number corresponded with the prir.ted serial 13 numbers at 13.
14 In practice, a digital signal recorder would receive the improved article and read stripe 0 to identify 16 the particular article. In a preferred form of using 17 the improved article, apparatus employing the article 18 would identify which articles had never been used, 19 i.e., "scratch" articles, and other articles which had previously received recording. For such "scratch"
21 articles, stripe 0 is initially read, the article moved 22 to stripe 1, with the serial number then recorded in 23 stripe 1. Subsequent loading of such article into 24 a digital signal recorder apparatus causes the apparatus to move to stripe 1 for reading the scrial numbcr.
26 In this manner, possible erasure or othcr d~.truction 27 of the serial numbers in stripe 0 is minimizcd. One 28 procedure for effecting such protective reading is to ~0973039 _9_ 1 always have the digital recorder step to stripe 1.
2 If the stripe is erased, then stripe 0 is read. If 3 the stripe 1 is in error, then additional stripes 2-9 4 may be employed for receiving such serial number. Addi-tionally, other data may be recorded in stripes 1-9, 6 such as usage indicators, error status, and other in-7 formation usually found in header labels of one-half 8 inch magnetic tape record media.
9 The longitudinal space extending from point 26 to BOT and disposed intermediate servo areas 17 11 and 19 is reserved for density and code indicating 12 information. Such an area may accommodate up to 100 13 stripes, for example. When the first type of recording 14 is employed, then all of such stripes in areas 26 to BOT are left blank. For a first modification, such 16 as increased density, variation of stripe width, spacing, 17 etc., a first particular code is inserted in the density 18 area between space 26 and BOT, identifying the newer 19 recording format. By such identification, backward compatibility of the recorded improved article is iden-21 tifiable.
22 In accordance with all of the above, the 23 improved article, when shipped from a manufacturing 24 plant, includes servo stripe areas 17 and 19 with their associated servo stripes, identification and addressing 26 area 25, and the printed serial numbers at 13. ~r(~a 2~
27 can have addresses 00000 to 13342 (decimal). rhc addrc;s 28 signals consist of two eight-bit binary codcd bytes 1 which may be subjected to error correction codes or be 2 redundantly recorded, as one pleases. All recording is 3 inset from longitudinal edges 30 and 33 to provide a 4 guard area of no recording.
Referring now more particularly to FIGURE 2, 6 the relationship of the improved article to a particu-7 lar digital signal recorder with which the improved 8 article can be advantageously employed is described.
9 The timing relationship of the rotating head scanning of the tape with respect to the servo track areas and 11 the identification and address stripe show the advan-12 tageous usage. As mentioned above, in a first constructed 13 embodiment of the improved article, the angle of the 14 data stripes, such as stripes 21 and 22, with respect to the longitudinal edges of the tape, is about 17-1/2.
16 The data receiving areas 21 and 22 extend at such an 17 angle between the precisely aligned servo areas 17 18 and 19. The lateral extent of the servo areas 17 and 19 19, as measured along the scan path 27 of a rotating head, is slightly less than the intergap distance between 21 a write (W) and a read (R) gap of the single two-gap 22 head on the rotor, as will be later described. This 23 intergap distance, as at 28, being slightly greater 24 than such transverse dimension of the servo areas, is advantageously employed when recording and stepping 26 the improved article by a digital signal rccorder.
27 Assume that when gap W is scanning the tape at thc 28 lower edge 30, it is connected to a readback circuit.

1 Gap W scans the address portion 25. The readback sig-2 nals being identified as data signals are ignored.
3 As gap W scans servo area 19, the readback signals 4 are identified as servo signals and sent to a servo- -mechanism used in connection with transporting article 6 11 past the rotating heads having gaps W and R. As 7 gap W scans area 19, at 17-1/2, trailing gap R follows 8 by distance 28 to simultaneously scan address area 9 25. The servo signals from gap W drive the servo-mechanism simultaneous with other readback circuits, 11 analyzing the signals from area 25 to identify the 12 location of the improved article with respect to gap 13 W. After gap R has completed a scan of the appropriate 14 portion of address area 25 signals, electronic circuits determine whether or not the article is appropriately 16 positioned. If it is, then recording currents are 17 turned on for recording data signals in stripe area 21, 18 precisely aligned along the 17-1/2 scan path with 19 the appropriate portion of servo tracks in area 19, as well as the later-described address portion of area 21 25 associated with data signal receiving area 21. As 22 gaps W and R continue to scan across tape 11, the sig-23 nals are recorded through gap W into data signal receiving 24 area 21. For checking the correctness of the recording in area 21, the recorded signals are simultaneously 26 sensed by gap R as it scans area 21. Such read-after-27 write recording verification can follow the same pro-28 cedures used in connection with prior digital data 29 signal recorders, such as employed for 1/2" tapes.

1 As gap W leaves area 21, as at 31, all 2 recording currents are removed from the gap. Gap R
3 continues to sense the recorded signals. Gap w senses 4 the area 17 servo signals to supply servo track signals to said servomechanism for use in connection with posi-6 tioning the article, as is well known. Since the inter-7 gap distance 28 is slightly longer than the 17-1/2 8 transverse dimension of area 17, gap W leaves area 9 17, as at 32, about substantially coincidentally with gap R leaving area 21, as at 31. At this time, gap R
11 is substantially transversely inward of upper edge 12 33 of tape 11. The servomechanism is now actuated 13 to step the article 11 to the next stripe, such as 14 stripe 22. The constants of acceleration and the rotor velocity can be matched such that the stepping to stripe 16 or signal receiving area 22 is the same time it takes 17 for gap W to move from area 17 to just immediately 18 prior to area 19 which is aligned with stripe 22. This 19 transit time corresponds to the transverse dimension from area 17 to edge 33, plus the distance from edge 21 30 to lower edge 34 of area 19. This statement assumes 22 a helical wrap of 360 of article 11 around a later-23 described mandrel, such that edges 30 and 33 abut.
24 In this manner, for a single head type rotor, a minimum time is lost because of the rotor movement and tape 26 movement for maximizing data signal throughput.
27 Referring next to FIGURE 3, thc dctailed 28 relationship of the address area 25 with respect to 10~6406 the data rece1v1ng area 16 1s further expla1ned. The address area 25 1s recorded on the 1mproved art1cle 1n accordance w1th the Harr U.S.
Patent No. 3,366,897. Area 25 1ncludes one address s1gnal rece1v1ng area 40 correspond1ng to each data s1gnal str1pe or rece1v1ng area, such as areas 21 and 22 of FIGURE 2. Areas 40 are prec1sely al1gned along the 17-1/2 scan path, w1th correspond1ng servo 1nformat10n s1gnals 1n the servo areas 17 and l9. For example, assume that str1pe J 1s to be accessed, It has an address area JID ln area 25, wh1ch 1dent1f1es the long1tud1nal address of str1pe J. Read and wr1te gaps R and ~ scan the hatched area 42 of address port10n JID. The gap cen-ter 11ne 43 1dent1f1es the scan path of both gaps. Str1pe J, after record1ng by a su1table pos1t10n1ng based upon the servo tracks 1n area 19, correspond1ng to servo pos1t10n1ng 1nd1cat1ng s1gnals as ~t 44 and 45, 1s prec1sely al1gned w1th JID center portton. In a slm11ar manner, servo track area 17 has an add1t10nal pa1r of servo pos1t10n1ng s1gnals correspond1ng to str1pe J.
The s1gnal envelope appear1ng from gap R 1n read1ng JID and str1pe J 1s shown 1n the lower part o~ FIGURE 3. S1gnal envelope port10n A corresponds to gap R read1n~ port10n A of JID+l; 1.e., only a portton of the gap R senses JIUIl. The space between A and the s1gnal JID' 1s the 1nteraddress gap, as at 50. The JID' s1gnal represents a full scan of the 1 address area JID, enabling signal detection in accor-2 dance with known techniques. Following the JID' sig-3 nal, gap 51 appears, followed by signal B from gap 4 R sensing the B portion of address area JID-l. Then, the servo tracks are sensed (envelope now shown); fol-6 lowing that, the data stripe J is sensed, as indicated 7 by the signal J' followed by sensing the servo tracks 8 from area 17, the signal envelope which is not shown.
9 It should be noted that the addressing and the data signals are read by gap R, while both servo 11 tracks are read by gap W. Additionally, gap W records 12 signals in the data stripe area, as well as selectively 13 recording signals on the address portion, as will be 14 later described. The preferred write gap to read gap ratio is about 2:1; i.e., the write gap scans a wider 16 track than the read gap as commonly practiced in one-17 half inch tape recorders.
18 Referring next to FIGURE 4, using the improved 19 article in a rotating head digital signal recording apparatus is further described. The improved article 21 11 has a helical wrap around an air bearing mandrel 22 consisting of two halves 60 and 61, the mandrel being 23 stationary. Precisely coaxially aligned with the cylin-24 drical mandrel 60, 61 is a single axially thin rotor 62 which carries gaps W and R, as above referred to.
26 The intergap distance is the short distance between 27 the gaps. A rotary transformer (not shown) of usual 28 design is included in rotor 62 to provide electrical 1 connections over lines 63 and 64, respectively, between 2 gaps W and R and electronic circuits diagrammatically 3 shown in FIGURE 4.
4 Rotor 62 is driven at a constant angular velocity by motor 70. Motor 70 also includes a precisely 6 constructed tachometer disk 71. Disk 71 has fiducial 7 mark 72 precisely aligned with the angular position 8 of gaps R and W such that sensor 73, supplying a sig-9 nal indicative of sensing fiducial mark 72, provides a precise relationship of the angular location of gaps 11 W and R for use in connection with the medium format 12 shown in FIGURES 1 and 2. .Sensor 73 supplies its fidu-13 cial signal to reset angular position counter 74 to 14 a reference state, such as all 0's. In addition, sensor 75 senses the positional marks evenly distributed around 16 the circumference of disk 71. Sensor 75 supplies cor-17 responding angular position-indicating signals to counter 18 74 to tally same for indicating the present angular 19 position of gaps R and W. For example, if the counter is set to all l's by the reset, then the tally signals 21 from sensor 75 decrement the counter toward zero as 22 motor 70 rotates rotor 62 and tachometer disk 71. In 23 the alternative, when counter 74 is set to all 0's, 24 the tally signals from sensor 75 may increment the counter. Other reference states may be used in the 26 counter in accordance with machine design principles.
27 The present count in counter 74, i.e., the 28 indication of the angular position of gaps R and W, 1 passes head-switching positions represented by signals on 2 the lines 80, 81, and 82. These positions correspond 3 to the read and write gap positions, as shown in FIGURE
4 2.
Since the apparatus is employed for recording 6 digital data signals, a computer (not shown) is usually 7 connected to the apparatus, no limitation thereto in-8 tended. The computer supplies the usual control sig-9 nals for digital signal recorders and, in addition, supplies digital signals to be recorded. Recording 11 circuits 84 receive the computer-supplied signals and 12 convert them to a form suitable for recording on article 13 11. Such a form may be NRZI digital signals, as taught 14 by Phelps in U. S. Patent 2,774,646. Such NRZI recording, as taught by Phelps, is preferably encoded for reducing 16 the charge effects in the rotary transformer. To this 17 end, the record code taught by Patel in commonly assigned 18 United States Patent Number 3,906,485, issued September 16, 1975, 19 may be advantageously employed for recording signals in the data signal receiving area 16, as well 21 as certain signals to be recorded in the address area 22 25. Such recording includes a preamble clock synchro-23 nizing set of signals, such as those employed in phase-24 encoded recording.
Signals to be recorded are supplied by recording 26 circuits 84 through AND or coincidence circuit 85 for 27 being supplied over line 63 to gap W. AND 85 passes 28 such signals only when the gap W is scanning that portion 1 of article 11 corresponding to the digital data signal 2 receiving stripes in area 16. Counter 74 is constructed 3 to decode the counts for defining data signal receiving 4 area 16 by supplying a relatively low amplitude signal over line 80; i.e., the signal on 80 represents a series 6 of tachometer counts from disk 71 corresponding to 7 the scan portion represented by stripes 21, 22, etc.
8 The signal on line 80 is supplied through inverting 9 amplifier 86 to AND 85 for enabling the recording of signals by gap W. At all other times, coincidence 11 circuit 85 is disabled, thereby protecting the integrity 12 of the signals recorded a~ a manufacturing plant in 13 servo areas 17 and 19 in accordance with the Harr patent, 14 supra.
Gap W scans the servo areas 17 and 19, which 16 have a predetermined relationship with the above-17 mentioned data receiving area, such that a second pre-18 determined set of counts from disk 71, as manifested 19 in counter 74, can be used to open AND circuit 87 to pass signals from line 63 to servo circuits 90. In 21 this regard, whenever address area 25 is not to be 22 updated, the signal on line 80 is passed through OR
23 circuit 91 to enable AND 87 whenever AND 85 is disabled.
24 Hence, in this manner, the signals on line 63 are passed to servo circuits 90 whenever the gap W is scanning 26 a portion of the tape outside the data signal rcceiving 27 area. Servo circuits 90 are constructcd to ignorc 28 the data signal type of readback signals.

1 In addition, gap R supplies signals over 2 line 64 to a set of readback circuits 95. Readback 3 circuits 95 supply such readback signals to the compu-4 ter whenever gap R is scanning signals in the data signal receiving area 16. This is indicated by the output of inverter 86. At other times, gap R is scan-7 ning area 25, which is indicated by the signal on line 8 81. In a similar manner, the signal on line 82 indi-9 cates gap R is scanning a nondata area of the tape.
Similarly, the signal on line 82 disables readback 11 circuits 95 whenever gap R is not scanning a signal 12 receiving area on tape 11.
13 As additional controls and variations of 14 modification of the signals are recorded on improved article 11, electronic circuits associated with a given 16 digital signal recorder must necessarily become more 17 complicated. In the preferred form of the invention, 18 address area 25 has a set of addresses beginning at 19 zero adjacent BOT extending through a predetermined number of stripes at EOT, for example, 13,342, with 21 the stripes being spaced center-to-center of about 22 ten mils with a width of six mils, leaving an inter-23 address space of four mils. The data signal receiving 24 stripes 21 and 22 can be made contiguous provided the recording signal apparatus has sufficiently accurate 26 servo circuits and guiding apparatus (not shown) for 27 precisely aligning each of the stripes as diagrammati-28 cally illustrated in FIGURES 1 and 2.

~066406 S1nce record1ng 1n data slgnal area 16 1s 1n1t1ated only after the art1cle has been accurately pos1t10ned and such pos1t10n1ng ver1f1ed, all data str1pes 00000 to 13,342 are prec1sely Dl1gned w1th the correspond1ny port10ns of the servo track areas l~, l9 and address s1gnals at 25. Pos1tlon1ng control lO0 coord1nates med1um ll trans-port w1th rotor 62 pos1t10n 1n a known manner. Supply or payout reel lOl dr1ven by motor 102 and capstan-reel or takeup reel 103 v1a motor 104 are also coord1nated 1n operatton ln accordance w1th Phlll1ps U.S.
Patent No. 3,781,490. Tachometer lOS suppl1es pos1t10n data s1gnals to control lO0. Translat10n of capstan-reel 103 rotatlon to actual 11near tape mot10n 1s calculated by the computer 1n accordance wlth tape wrap rad1us on capstan-reel 103. Thread1ng med1um ll from reel 101 to reel 103 1s 1n accordance wlth establlshed automat1c thread1ng techn1ques.
It 1s ant1c1pated that the 111ustrated record med1um may be used by several d1fferent tape un1ts as dlagrammatlcally shown ln FIGURE 4. Such tape unlts usually wlll have dlfferent tape-guld1ng characterlstlcs y1eldlng sllghtly dlfferent record strlpe angles --such angle dlfferences are termed "skew". Such skew can result ln readback errors, unlntended record1ng overwrltlng resultlng ln obllteratlon of prevlous records. In sp1te of thls skew problem, lt 1s co~merclally 1mperat1ve that record strlpes be changeable w1thout un1ntent10nally obl1teratlng any recorded s1g-1 nals. For achieving such a re-recording capability 2 without error, record stripes 20 are grouped into 3 record blocks such as 110 and 111, each such record 4 block being separated by an area 112 containing no recorded signals. To re-record, one entire block 110 or 111 is recorded at a time. Following such a prac-7 tice accommodates tape-guiding tolerances of various 8 tape units.
9 Each record block may contain any number of record stripes 20; it is preferred that a fixed number 11 of record stripes be selected, such as 50, 100, etc.
12 Such a selection simplifies programming in computers 13 using the illustrated record medium for data signal 14 stoxage.
For maximizing data signal storage on each 16 medium, area 112 (termed interblock gap or IBG) has a 17 minimal length, for example, a length sufficient to 18 accommodate one or two record stripes. Identification 19 portion 25 can contain special indicia (all l's, etc.) signifying an IBG, the computer recognizes IBG's by 21 specified addresses, or the IBG can extend into portion 22 25.
23 It is preferred, for maximum flexibility~ that 24 each block and IBG be identified by decimal address such as set forth below for a 65-stripe block:

1 Block Number Block Addresses IBG Addresses 8 i.

11 N66N - (66-N+64) 66N + 65 12 Each address consists of two bytes (address 13 modulus of 216-1) recorded in the ID portion 25 in accor-14 dance with the Patel et al U.S. Patent No. 3,906,485 ~'!
and Harr U. S. Patent 3,666,897. The recorded signals 16 appear in seriatim at the 17-1/2 angle.
17 While the invention has been particularly 18 shown and described with reference to a preferred em-19 bodiment thereof, it will be understood by those skilled in the art that various changes in form and detail 21 may be made therein without departing from the spirit 22 and scope of the invention.

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Claims (4)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A new article having a flexible longitu-dinally elongate substrate having a magnetic coating substantially over its longitudinal length and a pair of longitudinal edges, one of which is a reference edge, a leader end and a spool end, the improvement including in combination:
first and second laterally spaced-apart longi-tudinally extending servo tracks each consisting of a longitudinal extending series of record area desig-nating signals, corresponding signals defining trans-verse ends of a recording area adapted to receive data signals serially arranged along a given line extending through said corresponding signals, respectively;
said given line subtending an acute angle with respect to said reference edge and opening toward said leader end;
said first servo track being laterally spaced from said reference edge a distance less than one-fourth the lateral extent of said article;
address indicia recorded along each of said given lines and disposed laterally intermediate said reference edge and said first servo track; and said second servo track being laterally adja-cent a second one of said longitudinal edges.

2. The new article set forth in Claim 1 wherein both said servo tracks extend longitudinally closer to said leader end than said address indicia.

3. The new article set forth in Claim 2 further including a set of article-identifying signals recorded in a one of said given areas longitudinally closest to said leader end; and visible indicia signifying said article identifying signals and disposed longitudinally imme-diately adjacent said leader end and being longitudi-nally spaced from said servo tracks.

4. The article set forth in Claim 2 wherein spacing along each said given line of said recorded address indicia and said first servo track is greater than spacing of said second servo track and said given area.