This standard specifies the track configuration, track format and characteristics of recorded signals. GB/T 15130.2-1995 Information processing data interchange 90 mm modified frequency modulation recording bit density 15916 flux reversals/radian, 80 tracks per side floppy disk Part 2: Track format GB/T15130.2-1995 standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Information processing-Data interchange on 90 mm flexible disk cartridges using modified frequency modulation recordingat 15 916 ftprad, on 80 tracks on each sidePart 2: Track format
GB/T 15130.2—1995
ISO/IEC 9529/2—1989
This standard is equivalent to the international standard IS0/IEC9529/2—1989 "90 mm flexible disk cartridges using modified frequency modulation recordingat 15 916 ftprad, on 80 tracks on each sidePart 2: Track format". 0 Introduction
GB/T15130 specifies the performance of 90 mm floppy disks with a bit density of 15916 flux turns/radian and 80 tracks per side recorded using the modified frequency modulation system (MFM).
GB/T15130.1 specifies the dimensions, physical properties and magnetic properties of floppy disks. This provides the possibility of practical exchange between data processing systems.
GB/T15130.1 and GB/T15130.2 provide the conditions for full data exchange between data processing systems with the numbering system specified in GB/T13703.
1 Subject matter and scope of application
This standard specifies the track configuration, track format and characteristics of recorded signals. 2 Conformity
If a 90 mm floppy disk meets all the requirements of this standard, the floppy disk is consistent with this part of GB/T15130. The prerequisite for consistency with this part of GB/T15130 is consistency with GB/T15130.1. 3 Referenced standards
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. When this standard is published, the versions shown are valid. All standards will be revised, and parties using this standard should explore the possibility of using the latest versions of the following standards. GB1988 Information processing - seven-bit coded character set for information exchange GB2311 Information processing - code expansion technology for seven-bit and eight-bit coded character sets GB11383 Information processing - eight-bit code structure and coding rules for information exchange GB/T13703 Information processing - floppy disk volume and file structure for information exchange GB/T15130.1 Information processing - data exchange - 90mm improved frequency modulation system - the bit density of the record is 15916 flux reversals/arc - State Administration of Technical Supervision - 1995-12-13 Issued 410
1996-06-01 Implemented
4 General requirements
4.1 Recording method
GB/T 15130.2--1995
Flexible disk with 1000 MHz and 80 tracks per side Part 1: Dimensions, physical properties and magnetic properties The recording method is modified frequency modulation (MFM), with the following conditions: Write a flux reversal at the center of each bit cell containing "1": a.
b. A flux reversal is written at each cell boundary between consecutive bit cells containing "0\". Except as specified in 4.12.
4.2 Track position tolerance of recorded floppy disk For GB/T15130.2, the nominal track position specified in 9.2.3.1 of GB/T15130.1 needs to be temporarily corrected to the value at the actual temperature using the thermal expansion coefficient specified in 8.2 of GB/T15130.1. Within the entire range of use environment specified in 6.1.2 of GB/T15130.1, the recorded track centerline should be within ±0.028mm of the corrected nominal track position. 4.3 Recording deviation angle (see Figure 1)
At the moment of writing or reading a flux reversal, the flux reversal has an angle as shown in formula (1): = arcsin(d/Rn) ± 0°18
Where: R,-
The radius through which this flux reversal passes (see 9.2.3.1 of GIB/T15130.1). (1))
Note: Since the track may be written and rewritten at the edge of the tolerance given in 4.2 and 4.3, part of the original information may be left on one side of the newly written data, forming unwanted noise when reading. Therefore, it is necessary to use the write-after-erase method to trim the track edge. Avoidance
Track centerline
Direction of rotation
Access line
4.4 Recording density
4.4.1 The nominal recording density is 15916 flux reversals/radian, and the nominal bit unit length is 62.8urad. 4.4.2 The average bit unit length of the long term should be The average value of the bit cell length measured over the entire sector. It should be within ±2.5% of the nominal bit cell length.
4.4.3 The average bit cell length of the short term (relative to a specific bit cell) should be the average of the lengths of the 8 preceding bit cells. It should be within ±8% of the average bit cell length of the long term.
4.5 Flux reversal spacing (see Figure 2)
GB/T15130.2—1995
The instantaneous distance between flux reversals is affected by the read-write process, the order of recorded bits (pulse crowding effect) and other factors. The position of the reversal is the position of the signal peak during readout (see Appendix A (reference) and Appendix B (reference)). 4.5.1 The spacing between consecutive \1" flux reversals should be 80% to 120% of the average bit cell length of the short term. 4.5.2 The distance between the flux reversal between two "0"s and the flux reversal before or after them is 130% to 165% of the average bit unit length of the short term.
4.5.3 When there is only one "0" bit unit between two "1"s, the distance between the flux reversals of two "1"s should be 185% to 225% of the average bit unit length of the short term.
81% ~ 120%
4.6 Average signal amplitude
130% ~ 165%
130% ~ 165%
185% ~ 223%
The average signal amplitude on any track on each side of a floppy disk for data exchange (see 4.12 of GB/T15130.1) shall be less than 160% of the standard reference amplitude SRA of 1f and greater than 40% of the standard reference amplitude SRA2 of 2f. 4.7 Byte
A byte is a combination of 8-bit positions, identified by B1 to B8. The bit at each position shall be "0" or "1". 4.8 Sector
All tracks are divided into 18 sectors, and the data capacity of each sector is 512 bytes. 4.9 Cylinder
A pair of tracks with the same track number (one track on each side). 4.10 Cylinder serial number
The cylinder serial number is represented by two digits, which is the same as the track serial number of the track on the cylinder. 4.11 Data capacity of a track
The data capacity of a track is 9216 bytes. 4.12 Hexadecimal notation
The following bytes are represented in hexadecimal notation: (00) represents (B8～B1) = 00000000
(01) represents (B8～B1) = 00000001
(02) represents (B8～B1) = 00000010
(4E) represents (B8～B1) = 01001110
(FE) represents (B8～B1) = 11111110
(FB) represents (B8～B1) = 11111011
(A1) represents (B8～B1) = 10100001
In the (A1)* byte, there is no boundary flip between B3 and B4. 4.13 Error Check Character (EDC)
Two EDC bytes are generated by hardware, i.e., by serial shifting the relevant bits (see GB/T 15130. 2-1995 for each part of the track) through a 16-bit shift register (see Appendix C (reference)). Its generating polynomial is: X1 +X12 +X5 + 1
Track Configuration
The formatting of the track should start from the appearance of the index. The index should be at the baseline B (see GB/T15130.1 7.4.2.2) parallel to the access line and appear within 440 us. During formatting, the disk speed should be: the average speed from index to index is 300/min±2%, and the average speed of the entire sector is 300r/min±2.5%. After formatting, each track should have 18 sectors, and the track configuration of each track is shown in Figure 3. Index gap
5.1 Index gap
Identifier
Identifier
First opening segment
Data block
Data block||tt ||Data block
Sector 18
Data block
Under the nominal recording density, this field shall include 146 bytes, the contents of which are not specified (but shall not include (A1 )*byte). Due to overwriting, some of the first bytes in this field may become uncertain. 5.2 Sector Identifier
The configuration of this field is shown in Table 1.
Sector identifier
Identifier tag
12 bytes
3 bytes
5.2.1 Identifier tag||tt| |1 byte
This field consists of 16 bytes:
12 (00) bytes;
3 (A1) bytes;
1 (FE) bytes.
5.2.2 Address Identifier
This field consists of 6 bytes.
5.2.2.1 Track Address
This field consists of 2 bytes:
1 byte
Track Address
1 byte|| tt||(00) or (01)
Address identifier
1 byte
1 byte
2 bytes
Cylinder number (C)
GB/T15130.2—1995
This field uses binary notation to represent the cylinder number, from the outermost cylinder 00 to the innermost cylinder 79 Sequential numbering. b. Surface number (Surface)
This field indicates the surface of the disk. On side 0, the side number is (00) on all tracks. On side 1, the side number is (01) on all tracks.
5.2.2.2 Sector Number (S)
The third byte represents the sector number in binary notation, from 01 for the first sector to 18 for the last sector. . Sectors can be recorded in any order of sector numbers. 5.2.2.3 4th byte
The 4th byte is always a (02) byte. 5.2.2.4 EDC
These two bytes shall be in accordance with the provisions of 4.13, starting from the first (A1)* byte of the identifier tag (see 5.2.1) to the first (A2)* byte of the address identifier. The 4th byte (see clause 5.2.2.3) ends the generation of the sector identifier byte. If the EDC is incorrect, then the sector is defective. GB/T13703 specifies the treatment method for defective sectors. 5.3 Identifier Gap
This field consists of 22 initial recorded (4E) bytes. Due to overwriting, these bytes may become uncertain. 5.4 Data BlockWww.bzxZ.net
The setting of this field is shown in Table 2.
Data block
Data tag
12 bytes
5.4.1 Data tag
3 bytes
This field includes 16 bytes:
12 (00) bytes;
3 (A1)* bytes;
1 (FB) byte.
5.4.2 Data field
1 byte
Data field
512 bytes
2 bytes
This The field consists of 512 bytes. If it consists of fewer than the required number of data bytes, the remaining positions should be filled with (00) bytes. 5.4.3 EDC
These two bytes shall be in accordance with the provisions of 4.13, using the data block word starting from the first (A1)* byte of the data marker and ending with the last byte of the data field. Section generation. If the EDC is incorrect, then the sector is defective. GB/T13703 specifies the treatment method for defective sectors. 5.5 Data Block Gap
This field includes 101 initial recorded (4E) bytes. Due to overwriting, these bytes may become uncertain. The data block gap is recorded after each data block and before the next sector identifier. The data block gap after the last data block is located before the track gap.
5.6 Track Gap
This field should be placed immediately after the last sector's data block gap. Write (4E) bytes until the index is detected, unless writing 414||tt ||GB/T15130.2—1995
The index is detected when the last data block gap is reached, and there should be no track gap at this time. Coding representation of data
6.1 Standard
The content of the data field should be recorded and interpreted according to the relevant national standard for information coding (such as GB1988, GB2311 or GB11383).
6.2 Encoding method
6.2.1 When required by the encoding method, the data field shall be regarded as an ordered sequence of octets. In each byte, the bit positions are identified by B8 to B1. The highest binary digit is recorded at position B8 and the lowest binary digit is recorded at position B1. The order of records should be high byte first. When data is encoded according to an eight-bit binary code, the bit weights of the binary bits are shown in Table 3. Table 3
Bit Positions
When data is encoded according to a seven-bit binary code, and binary bit B8 is "0", the data should be encoded in positions B7 to B1 and use the bits shown in Table 3. The same position rights.
6.2.2 When required by the encoding method, the data field should be regarded as an ordered sequence of binary bit positions, each position being a binary
bit.
A1 General description
GB/T 15130.2—1995
Appendix A
Procedure and equipment for measuring flux reversal spacing (reference)
This The appendix specifies the procedure and equipment for measuring the flux reversal spacing on a 90 mm double-sided floppy disk with a density of 15916 flux reversals/radian recorded in the modified FM system.
The nominal speed of the test is 300r/min.
A2 format
The disk to be tested should be written by a floppy disk drive used for data exchange. A3 Test equipment
A3.1 Floppy disk drive
During the entire rotation period, the average rotation speed of the floppy disk drive should be 300±3r/min. The average angular velocity within 32 us should not deviate from the average angular velocity during the entire rotation by more than 0.5%. A3.2 Head
A3.2.1 Resolution
When using a reference floppy disk (RM9529) with known correction coefficients for the corresponding surface and a specified test recording current, the 79 tracks on each surface The absolute resolution of the magnetic head should be 70% to 75%. The resonant frequency of the magnetic head should not be lower than 500000Hz. The resolution cannot be changed by changing the head load impedance. The resolution shall be measured at the amplifier output as specified in Section A3.3.1. A3.2.2 Deviation angle
The deviation angle of the head should be as shown in formula (A1): = arcsin(d/R) ± 0°6'
Where: d0.35 mm.
A3.2.3 Contact
During the test, the head and disk should be in good contact. A3.3 Reading Circuit
A3.3.1, Reading Amplifier
-(A1)
The reading amplifier should have a smooth response curve of no more than ±1dB in the frequency band from 1000 to 375000Hz. And amplitude saturation does not occur.
A3.3.2 Peak Sense Amplifier
The peak sense is measured using a differential and limiting amplifier, or an equivalent good peak sense circuit. A3.4 Resolution of measuring time intervals
The time interval counter should be able to measure time intervals from 5uμs to a minimum of 5ns. A4 Measurement steps
A4.1 Measurement of flux reversal spacing
GB/T15130.2—1995
By measuring - adjacent to 105 randomly sampled readout signals on a track The time interval between peaks is used to measure the flux reversal interval. The distribution of time intervals plotted logarithmically is shown in Figure A1. These measurements shall be made at the output of the sense amplifier specified in Section A3.3. A4.2 The flux reversal interval
of all tracks is measured over a time interval up to t. As shown below: t2/t. and t//to (×100%) corresponds to 4.5.1. ta/to and t3/to (×100%) correspond to 4.5.2. ts/t and ts/to (×100%) correspond to 4.5.3. t. is the average bit unit length of the short term, and its nominal value is 2us. The situation where the interval exceeds the specified value due to the splicing of data blocks or indexes should be ignored.
Appendix B
Data separator for decoding by MFM recording method
(reference)
B1 The nominal flux reversal interval given by the improved frequency modulation (MFM) recording method is: t represents the pattern code 111 or 000;
3t/2 represents the pattern code 100 or 001;
2t represents the pattern code 101.
The data separator should be able to distinguish the time difference of 2us. To achieve this and ensure a low error rate, the data separator cannot operate in a fixed cycle, but should be able to vary with the length of the bit unit. Dynamic data separation can be achieved through various technical means. The most mature method at present is to construct an analog data separator based on a phase-locked oscillator, which can meet the necessary reliability. Appendix C EDC Execution Process (Reference) C1 Figure C1 is a feedback connection diagram of the shift register that can be used to generate the EDC byte. Before operation, all bits of the shift register are set to "1". The input data is added (XOR) to the stored value of C15 of the register to form feedback. This feedback signal is added (XOR) to the stored value of C1 and Cn in turn. During the shift, the output of the XOR gate is sent to C1, C2, and C3 respectively. When the last data bit is added, the register is shifted once again according to the above regulations.
At this time, the register contains the EDC byte.
If the register is still shifting when the EDC byte is written, the control signal is used to prohibit the XOR operation. In order to detect whether there is an error when reading, the data bits should be added to the shift register in exactly the same way as when writing. After the data is input, the EDC byte is also sent to the shift register as data. After the last shift, as long as the record is correct, the number stored in the shift register will be all "o".
(Write EDC)
Additional notes:
This standard was proposed by the Ministry of Electronics Industry of the People's Republic of China. This standard is under the jurisdiction of the Standardization Institute of the Ministry of Electronics Industry. The 33rd Institute of the Ministry of Electronics Industry and the Standardization Institute of the Ministry of Electronics Industry are responsible for drafting this standard. The main drafters of this standard are Li Jian, Zheng Hongren, Li Guixin, Dong Chengju, and Wang Dalan. 418
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