1、ECMA EUROPEAN COMPUTER MAN U FACTURERS ASSOCIATION GUIDELINES ON ADDITIONAL PARAMETERS RECOMMENDED FOR PROCUREMENT SPECIFICATIONS FOR 12,7 mm MAGNETIC TAPES ECMA TRI36 December 1986 Free copies of this document are available from ECMA, European Computer Manufacturers Association 114 Rue du Rhne - 12
2、04 Geneva (Switzerland) ECMA EUROPEAN CO RIPUTER MAN U FACTURE RS ASSOCIATION GUIDELINES ON ADDITIONAL PARANIETERS RECOMMENDED FOR PROCUREMENT SPECIFICATIONS FOR 12,7 mm MAGNETIC TAPES ECI1MA TR/36 December 1986 TABLE OF CONTENTS 1. SCOPE AND INTRODUCTION 2. REFERENCES 3. DEFINITIONS 3.1 Error 3.2 E
3、xtra Pulse 3.3 Missing Pulse 3.4 Permanent Error 3.5 Transient Error 3.6 Physical Recording Density 3.7 Data Density 4.1 Definition 4.2 Recommendation 4.3 Procedure 4. FLEXURAL RIGIDITY (STIFFNESS) 5. COATING ADHESION 5.1 Definition 5.2 Procedure 6. INHIBITOR TAPE 6.1 Definition, 6.2 Abrasivity 6.2.
4、1 Definition 6.2.2 Recommendation 6.2.3 Procedure 6.3 Stick/Slip 6.3.1 Definition 6.3.2 Recommendation 6.3.3 Procedure 6.4 Contamination 6.4.1 Definition 6.4.2 Recommendation 6.4.3 Procedure 7. DURABILITY 7.1 Short Length 7.1.1 Definition 7.1.2 Recommendation 7.1.3 Procedure 7.2 Long Length 7.2.1 De
5、finition 7.2.2 Recommendation 7.2.3 Procedure Paqe 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3 3 4 4 4 4 5 5 5 5 5 5 5 5 6 6 6 6 6 6 6 6 6 8. TAPE PERFORMANCE 8.1 Definition 8.2 Recommendation 8.2.1 At 126 ftpmm Physical Recording Density 8.2.2 At 356 ftpmm Physical Recording Density 8.3 Procedures 8.3.1 Us
6、ing Tape Certifier 8.3.2 Using Volume Error Statistics -1- 1. 2. SCOPE AND INTRODUCTION This Technical Report gives guidance on magnetic tape parameters that are considered important to ensure continued good perfor- mance of tape systems. When preparing purchasing specifications, these parameters sh
7、ould be considered in addition to parameters included in the Interchange Standard ECMA-62 as they constitute an important part in the description of the product. Whereas this report does not develop a model for a purchasing specifica- tion, it does provide a technical presentation of several param-
8、eters which should be included. In performing the procedures outlined in this Technical Report, the Care and Handling Requirements of ECMA Technical Report TR/11 and the test conditions of Section II of ECMA-62 should be strictly observed to give validity to any results obtained and to give a sound
9、basis for any correlation of results between purchaser and supplier. When considering correlation, test con- ditions should always be accurately reported as even small vari- ations may critically affect the results obtained, e.g. Abrasiv- ity is highly dependent on Relative Humidity. REFERENCES ECMA
10、- 6 2 ECMA TR/11 NASA RP-1075 : Data Interchange on 12,7 mm 9-Track : Guidelines for the Handling and Storage : Magnetic Tape Recording for the Magnetic Tapes. of Magnetic Tapes. Eighties A. Boese van Groenou and M.I.L. Uijerschout : A quick test on wear of head materials by recording tapes (wear sc
11、ar) in EI11 Transactions on Magnetics, &Vol. Mag-19 No 5, Sept. 1983 A. Begelinger and A.W.J. De Gee : Wear measurements using Knoop diamond indentations, in wear, 43 (1977) p. 259-261 Elsevier Sequoia SA, Lausanne 3. DEFINITIONS 3.1 3.2 3.3 Error An error is due to the presence of an extra pulse or
12、 to the occurrence of a missing pulse. Extra Pulse An extra pulse is a pulse detected on a totally DC erased tape with a base-to-peak amplitude higher than an agreed level (See ECMA-62 Paragraph 5.16.2). Miscinq Pulse A missing pulse is a pulse detected on a tape written with flux transitions of con
13、stant frequency and amplitude with a base-to-peak amplitude lower than an agreed level (See ECMA-62 Paragraph 5.16.1). -2- 3.4 3.5 3.6 3.7 4. 4.1 4.2 4.3 Permanent Error An error, whether due to a missing pulse or to an extra pulse, which recurs after an agreed number of attempts is made to read the
14、 same area of tape. Transient Error An error, whether due to a missing pulse or to an extra pulse, which does not recur after an agreed number of attempts is made to read the same area of tape. Physical Recordins Density The number of flux transitions per unit length of track Data Density The number
15、 of data characters stored per unit length of the tape (cpmm). (ftpmm) FLEXURAL RIGIDITY (STIFFNESS) Definition The ability of the tape to resist bending. Recommendation The flexural rigidity (EI) of the tape shall be between 0,63 N.mm2 and 0,32 N.mm2. Procedure Clamp a 180 mm sample of tape in a un
16、iversal testing machine, allowing a 100 mm separation between the machine jaws. Set the jaw separation speed at 5 mm per minute. Plot force against distance. Calculate the flexural rigidity using the slope of the curve between 2,2 N and 6,7 N. The calculation is : E = 6F/wT 6L/L I = wT3 /12 6FT2 126
17、L/L Flexural rigidity = Where : 6F = change in force in N T = measured thickness in mm W = measured width in mm 6L/L = change in sample length between the jaws divided by original length between the jaws. 5. COATING ADHESION 5.1 Definition The force required to peel any part of the coating from the
18、tape base material shall not be less than 1,s N. - 3 ,- 5.2 Procedure i) Take a sample of the tape approximately 300 mm long and scribe a line through the recording coating across the wrath of the tape 125 mm frox one end. sample to a smooth metal plate, with the recording sur- face facing the plate
19、. iii) Fold the sample over 180, attach the metal plate and the free end of the sample to the jaws of a universal testing machine and set the speed of the jaw separation to 254 mm per min. separates from the base material. If this is less than 1,s N, the test has failed. If the sample peels away fro
20、m the double-sided pressure sensitive tape before the force exceeds 1,s N, an alternative type of double-sided pres- sure sensitive tape shall be used. iv) for the back coating. ii) Using a double-sided pressure-sensitive tape, attach the iv) Note the force at which any part of the coating first v)
21、If the back surface of the tape is coated, repeat i) to CI tape 6. INHIBITOR TAPE 6.1 Definition A tape that reducers affects the performance of the tape drive or other tapes, is called an inhibitor tape. Certain tape characteristics can contribute to degraded tape drive performance in respect of da
22、ta performance or in extreme cases, tape drive malfunction (e.g. column vacuum collapse). These characteristics include poor edge conditions such as edge lip (rippled edge), tape creases, excessive tape wear products, interlayer slippage, the tendency of the oxide coat- ing to transfer to the back o
23、f the reels next layer, as well as the tendency for the tape constituents to separate and cause deposits that could give tape stiction or prevent normal -4- performance of other tapes. Tapes which have any of the above characteristics may not give satisfactory performance and may result in excessive
24、 errors. These tapes are known as inhibitor tapes. The following tests although not exhaustive are designed to test tapes for inhibitor characteristics : 6.2 Abrasivity 6.2.1 Definition The tendency of the tape to wear the tape drive. There are several methods of measuring comparative abrasiv- ity i
25、nvolving the following : i) Brass shim (NASA/1075) ii) Radio-active trace (NASA/1075) iii) Thin films (NASA/1075) iv) Knoop diamond indentation VI Wear Scar Whereas the above methods can be reasonably quick and pos- sibly low cost, they only give an indication of potentially abrasive magnetic tapes.
26、 Measurements may also be be made using the tape drive and its recording head. The values given in 6.2.2 apply for non-ceramic heads. The procedure in 6.2.3 may be used for any recording heads. Following the first 1000 full length passes of 732 m of tape, the recording head wear shall not exceed 2,1
27、7 um, with a pass being defined as either BOT to EOT or EOT to BOT. This recording head wear shall not exceed 0,64 um for any subsequent 1000, passes and over a total of 30000 passes the recording head wear shall not exceed 19,69 um. Using talysurf equipment or equivalent, perform a profile trace of
28、 a new recording head across both the read and write heads at their respective gaps. Mount the recording head assembly onto the tape drive and perform routine main- tenance and cleaning to ensure correct tape tensions and to minimise the influence of contaminants. Cycle the tape un- der test for 200
29、 full length passes, using stop-start times of 5 ms while cleaning at the end of each 50 full length passes. At the end of 200 passes, perform a second profile trace to obtain an early indication of the abrasivity but noting that the head wear is usually greatest during the first few passes. Using t
30、he same recording head, perform the same procedure for a further 800 passes using four ad- ditional tapes of the same tape formulation to obtain a profile trace at 1000 passes. If the average wear is in ex- cess of the requirement at 1000 passes the test should be continued to a total of 30000 passe
31、s. For this continued test, profile traces need only be taken at each 1000 pass point or until it is established that the tape formulation under test has excessive abrasivity. 6.2.2 Recommendation 6.2.3 Procedure -5- 6.3 Stick/Slip 6.3.1 Definition This property of the tape is assessed by observing
32、the ve- locity profile of the tape after the initiation of a GO signal. Variations in the velocity profile may lead to data errors due to stick or slip conditions between the tape and the recording head, capstan or any other contacting sur- f ace. 6.3.2 Recommendation At the end of the first pass in
33、 the test described below, the velocity profile of the reverse start at the end of tape shall be free of inflection points (i.e. no erratic motion and/or glitches) between 10 % and 90 % of nominal velocity during reverse acceleration. In determining in- flection points, comparison should be made to
34、the velocity profile of the forward start. The time taken to reach 90 % of nominal velocity from initiation of a GO signal shall not be greater than 125 % a reverse start performed in the region of BOT. The above recommendation shall hold for the Testing Envi- ronment of ECMA-62 and when the tape is
35、 stress conditioned as follows : i) Write the tape continuously at 356 ftpmm to the EOT marker. ii) Stress-condition the tape at 48OC and 80 % Relative Humidity for 48 hours in a suitable environmental chamber. iii) Acclimatise in the Testing Environment for 24 hours. 6.3.3 Procedure Clean the tape
36、drive in accordance with its maintenance manual. Write the tape continuously at 356 ftpmm for 10 me- tres and measure the time taken to reach 90 % of the nomi- nal velocity from the initiation of a GO signal for a re- verse start. Write the tape continuously at 356 ftpmm to the EOT marker and leave
37、the tape loaded and stationary for 5 minutes, then again measure the time taken to reach 90 % of nominal velocity from initiation of a GO signal for re- verse start. 6.4 Contamination 6.4.1 Definition A tape which causes variation in signal amplitudes due to tape material which separates the tape fr
38、om the head. 6.4.2 Recommendation The average signal amplitude from the second pass shall be at least 90 % of that measured at corresponding points dur- ing the first pass. 6.4.3 Procedure Clean the tape transport in accordance with its maintenance manual. No further cleaning should be performed dur
39、ing this -6- test. On the first pass, measure the read-while-write am- plitude at 126 ftpmm on two tracks adjacent to the centre track (e.g. tracks 4 and 6) at the beginning of the tape and at the end of the tape. Unload the tape and stress-condition the tape for 24 hours at 52 OC and 15 % Relative
40、Humidity before acclimatising for 24 hours at the test environment. Repeat measurements for read-while-write amplitudes at the beginning of the tape and the end of tape on the same two tracks. 7. DURABILITY 7.1 Short-Lenqth 7.1.1 Definition The ability of the tape to withstand the wearing action en-
41、 countered during repeated reading of a short file of data. 7.1.2 Recommendation Under the conditions of the following test procedure, the tape should average at least 40000 read passes before a permanent error is encountered. Write a length of tape from BOT with 10 records of 2000 characters each,
42、phase-encoded recording. No write errors are allowed during the write pass. Then read the 10 records (read forward/rewind) repeatedly until a permanent read er- ror occurs. The test is to be performed with sufficient stop time (e.g. 20,O milliseconds) to ensure that the tape comes to a complete stop
43、 for each record. 7.1.3 Procedure 7.2 Lonq-Lenqth 7.2.1 Definition The ability of the tape to resist the wearing action en- countered while cycling full length on a tape drive. At least 90 % of the tapes tested should meet the following criterion : Tapes tested for use at 126 ftpmm should not averag
44、e more than three write errors per pass, or exceed ten write er- rors on any single pass for a minimum of 200 forward passes on tape drives that operate at 126 ftpmm. Write a 732 m length of tape in start/stop mode with 2000- character records using phase-encoded recording on each pass. Record the n
45、umber of write errors and repeat until 200 passes have been completed. In order to determine the effect of wear particles generated during the test do not clean the tape drive between passes. 7.2.2 Recommendation 7.2.3 Procedure -7- 8. TAPE PERFORMANCE 8.1 Definition Tape performance is a quality cr
46、iterion of the tape over its life-time. It is derived from the error behaviour of the tape. ECMA-62, clause 5.16 defines the parameters missing and extra pulses while identifying reasons why acceptable numbers are not specified. These reasons should be carefully noted when checking tape quality. Dat
47、a corruption due to missing and extra pulses will cause loss of time when writing data, due to write-error recovery procedures and will also cause a related loss of time when reading data. Generally a moderate number of such errors is acceptable to the user and later in this paragraph guidelines to
48、acceptable numbers are quoted. There are conditions, how- ever, e.g. when the tape may be repeatedly accessed in the same area, when any errors would, or could, result in unac- ceptable loss in performance. Where a large number of errors are noted, this is often indicative of poor surface quality an
49、d there is a strong likelihood of early deterioration in use. Errors fall into two categories, known as transient or perma- nent errors. There is commercially available equipment for measuring permanent and transient errors known as tape certi- fiers and evaluators although variation in numbers of the above errors reported may vary from one device to another. It is important therefore that in discussing numbers of errors a careful correlation exercise takes place and that such equip- ment is fully maintained to ensure its on-going quality of op- eration. It is worth noting that many tape sy
copyright@ 2008-2019 麦多课文库（www.mydoc123.com）网站版权所有
备案/许可证编号：苏ICP备17064731号-1