ANSI ISO 7487-2-1985 Information processing - Data interchange on 130 mm (5.25 in) flexible disk cartridges using modified frequency modulation recording at 7 958 ftprad I 9 tpmm (.pdf
《ANSI ISO 7487-2-1985 Information processing - Data interchange on 130 mm (5.25 in) flexible disk cartridges using modified frequency modulation recording at 7 958 ftprad I 9 tpmm (.pdf》由会员分享,可在线阅读,更多相关《ANSI ISO 7487-2-1985 Information processing - Data interchange on 130 mm (5.25 in) flexible disk cartridges using modified frequency modulation recording at 7 958 ftprad I 9 tpmm (.pdf(16页珍藏版)》请在麦多课文档分享上搜索。
1、International Standard $ 7487/2 0 a 4 4! b) a flux transition shall be written at each cell boundary between consecutive bit cells containing ZEROs, 1 IS0 7487/2-1985 (El Exceptions to this are defined in 4.1.12. 4.1.2 Track location tolerance of the recorded flexible disk cartridge The centrelines
2、of the recorded tracks shall be within f 0,085 mm (0.003 3 in) of the nominal positions, over the range of operating environment specified in IS0 7487/l. This tolerance corresponds to twice the standard deviation. 4.1.3 Recording offset angle At the instant of writing or reading a magnetic transitio
3、n, the transition may have an angle of 0 f 18 with the radius. This tolerance corresponds to twice the standard deviation. 4.1.4 Density of recording 4.1.4.1 The nominal density of recording shall be 7 958 ftprad. The nominal bit cell length for track 00, side 0 is 251 urad, and for all the other tr
4、acks it is 125,5 urad. 4.1.4.2 The long-term average bit cell length shall be the average bit cell length measured over a sector. It shall be within I!I 3,5 % of the nominal bit cell length. 4.1.4.3 The short-term average bit cell length, referred to a particular bit cell, shall be the average of th
5、e lengths of the preceding eight bit cells. It shall be within f 8 % of the long- term average bit cell length. 4.1.5 Flux transition spacing The instantaneous spacing between flux transitions may be in- fluenced by the reading and writing process, the bit sequence recorded (pulse crowding effects),
6、 and other factors. The lo- cations of the transitions are defined as the locations of the peaks in the signal when reading. Tests should be carried out using a peak-sensing amplifier. 4.1.5.1 Flux transition spacing for track 00, side 0 (see figure I) 4.1.5.1.1 The spacing between two clock flux tr
7、ansitions sur- rounding a data flux transition or between two data flux tran- L 9oxto 140% J sitions surrounding a clock flux transition shall be between 90 % and 140 % of the nominal bit cell length. 4.1.5.1.2 The spacing between two clock flux transitions not surrounding a data flux transition or
8、between two data flux transitions surrounding a missing clock flux transition shall be between 60 % and 110 % of the nominal bit cell length. 4.1.5.1.3 The spacing between a data flux transition and the preceding clock flux transition (when not missing) or between a clock flux transition and the pre
9、ceding data flux transition (when not missing) shall be between 45 % and 70 % of the nominal bit cell length. 4.1.5.2 Flux transition spacing for all tracks other than track 00, side 0 (see figure 2). 4.1.5.2.1 The spacing between the flux transitions in a se quence of ONEs shall be between 80 % and
10、 120 % of the short-term average bit cell length. 4.1.5.2.2 The spacing between the flux transition for a ONE and that between two ZEROs preceding or following it shall be between 130 % and 165 % of the short-term average bit cell length. 4.1.5.2.3 The spacing between the two ONE flux transitions su
11、rrounding a ZERO bit cell shall lie between 185 % and 225 % of the short-term average bit cell length. 4.1.6 Average signal amplitude For each side the average signal amplitude on any non- defective track (see IS0 7487/l) of the interchanged flexible disk cartridge shall be less than 160 % of SRAlfa
12、nd more than 40 % of SRAzf. 4.1.7 Byte A byte is a group of eight bit-positions, identified Bl to 88, with 88 the most significant and recorded first. The bit in each position is a ZERO or a ONE. C C 90 % to 140% 60% to 110% Figure 1 IS0 7487/2-1985 (El I 80% to 120% 130% to 165% 130% to 165 O/o 185
13、% to 225% - Figure 2 4.1.8 Sector All tracks are divided into 16 sectors. 4.1.9 Cylinder A pair of tracks, one on each side, having the same track number. 4.1.10 Cylinder number The cylinder number shall be a two-digit number identical with the track number of the tracks of the cylinder. 4.1.11 Data
14、 capacity of a track The data capacity of track 00, side 0 shall be 2 048 bytes. The data capacity of all tracks other than track 00, side 0 shall be 4 096 bytes. 4.1.12 Hexadecimal notation Hexadecimal notation shall be used hereafter to denote the following bytes : (00) for (88 to Bl) = 00000000 (
15、01) for (B8 to Bl) = 00000001 (FF) for (88 to Bl) = 11111111 (FE)” for (88 to Bl) = 11111110 where the clock transitions of B6, B5 and 84 are missing (FBI” for (88 to Bl) = 11111011 where the clock transitions of B6, 85 and 84 are missing (F8)” for (B8 to Bl) = 11111000 where the clock transitions o
16、f B6, 85 and B4 are missing (4E) for (B8 to Bl) = 01001110 (FE) for (88 to Bl) = 11111110 (FBI for (B8 to Bl) = 11111011 (F8) for (88 to Bl) = 11111000 (Al)” for (88 to Bl) = 10100001 where the boundary transition between B3 and 84 is miss- ing. 4.1.13 Error detection characters (EDC) The two EDC-by
17、tes are hardware generated by shifting serially the relevant bits, specified later for each part of the track, through a 16-bit shift register described by Xl6 + x12 + x5 + 1 (See also annex A.) 4.2 Track layout after the first formatting for track 00, side 0 After first formatting, there shall be 1
18、6 usable sectors on the track. The layout of the track shall be as shown in figure 3. During formatting the rotational speed of the disk, averaged index to index, shall be 300 f 6 r/min. 4.2.1 Index gap At nominal density, this field shall comprise 16 (FFI-bytes. Writing the index gap is started whe
19、n the index hole is detected. Any of the first 8 bytes may be ill-defined due to subsequent overwriting. 3 IS0 7487/2-1985 (E) INDEX SECTOR GAP IDENTIFIER IDENTIFIER GAP FIRST DATA BLOCK DATA BLOCK GAP LAST DATA BLOCK DATA BLOCK GAP TRACK GAP bp lst Sector -4 - - - 16th Sector - - - 4 Figure 3 4.2.2
20、 Sector identifier This field shall be as given in table 1. Table 1 Sector identifier Identifier mark Address identifier Track address S EDC C Side 6 bytes 1 byte 1 byte 1 byte 1 byte 1 byte 2 bytes (00) (FE)” (00) (00) (00) 4.2.2.1 Identifier mark This field shall comprise 7 bytes : 6 (OOI-bytes 1
21、(FE)*-byte 4.2.2.2 Address identifier This field shall comprise 6 bytes. 4.2.2.2.1 Track address This field shall comprise two bytes : a) Cylinder address (Cl This field shall specify in binary notation the cylinder ad- dress. It shall be (00) for all sectors. b) Side number (Side) This field shall
22、specify the side of the disk. It shall be (00) for all sectors. 4.2.2.2.2 Sector number (S) The 3rd byte shall specify in binary notation the sector number from 01 for the 1st sector to 16 for the last sector. The 16 sectors shall be recorded in the natural order : 1, 2, 3, . . . . 15, 16 4.2.2.2.3
23、4th byte of the sector address The 4th byte shall always be a (OOLbyte. 4 4.2.2.2.4 EDC These two bytes shall be generated as defined in 4.1.13 using the bytes of the sector identifier starting with the (FE)*-byte (see 4.2.2.1) of the identifier mark and ending with the 4th byte (see 4.2.2.2.3) of t
24、he sector address. 4.2.3 Identifier gap This field shall comprise 11 initially recorded (FFI-bytes. 4.2.4 Data block This field shall be as given in table 2. Table 2 4.2.4.1 Data mark This field shall comprise 6 (OOLbytes 1 (FBI*-byte 4.2.4.2 Data field This field shall comprise 128 bytes. No requir
- 1.请仔细阅读文档,确保文档完整性,对于不预览、不比对内容而直接下载带来的问题本站不予受理。
- 2.下载的文档,不会出现我们的网址水印。
- 3、该文档所得收入(下载+内容+预览)归上传者、原创作者;如果您是本文档原作者,请点此认领!既往收益都归您。
下载文档到电脑,查找使用更方便
10000 积分 0人已下载
下载 | 加入VIP,交流精品资源 |
- 配套讲稿:
如PPT文件的首页显示word图标,表示该PPT已包含配套word讲稿。双击word图标可打开word文档。
- 特殊限制:
部分文档作品中含有的国旗、国徽等图片,仅作为作品整体效果示例展示,禁止商用。设计者仅对作品中独创性部分享有著作权。
- 关 键 词:
- ANSIISO748721985INFORMATIONPROCESSINGDATAINTERCHANGEON130MM525INFLEXIBLEDISKCARTRIDGESUSINGMODIFIEDFREQUENCYMODULATIONRECORDINGAT7958FTPRADI9TPMMPDF
链接地址:http://www.mydoc123.com/p-437093.html