This standard specifies the quality of recorded signals, track configuration and track format for 130 mm floppy disks with a bit density of 13262 flux turns/radian for data exchange between data processing systems. GB/T 15131.2-1995 130 mm floppy disks with a bit density of 13262 flux turns/radian and 80 tracks per side for information processing data exchange using the improved frequency modulation system Part 2: Track format A (for 77 tracks) GB/T15131.2-1995 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Information processing--Data interchange on 130 mm flexible disk cartridges using modifiedfrequency modulation recording at 13262 ftprad, on80 tracks on each side-Part 2: Track format A for 77 tracksGB/T 15131.2—1995
ISO 8630/2—1987
This standard is equivalent to the international standard ISO8630/2—1987 "130 mm (5.25 in) floppy disks with a bit density of 13262 flux turns/radian and 80 tracks per side recorded by the modified frequency modulation system for information processing data exchange Part 2: Track format A (for 77 tracks)".
0 Introduction
GB/T15131 specifies the performance of 130 mm floppy disks with a bit density of 13262 flux turns/radian and 80 tracks per side recorded by the modified frequency modulation system (MFM).
GB/T15131.1 specifies the dimensions, physical properties and magnetic properties of floppy disks. This provides the possibility of practical exchange between data processing systems.
GB/T15131.3 specifies another track format for data exchange. The numbering system specified in GB/T15131.1 and GB/T15131.2 and GB/T15134 provides conditions for all data exchanges between data processing systems.
1 Subject matter and scope of application
This standard specifies the quality of recorded signals, track configuration and track format for 130 mm floppy disks with a bit density of 13262 flux reversals/arc for data exchange between data processing systems. 2 Conformance
When a floppy disk meets all the requirements of the first and second parts of GB/T15131 and uses one of the three sector capacities specified in Article 4.11, the floppy disk is consistent with GB/T15131. Data exchange is only possible when the same sector capacity is used. 3 Reference standards
GB 1988 Information processing
GB 2311
Information processing
Seven-bit coded character set for information interchange
Code extension technology for seven-bit and eight-bit coded character sets State Technical Supervision Bureau 1995-04-05 Approved 436
1995-12-01 Implementation
GB/T15131.2-1995
GB11383 Information processing Eight-bit code structure and encoding rules for information interchange GB/T 15131.11
130mm floppy disks with a bit density of 13262 flux turns/radian and 80 tracks per side for information processing data exchange Part 1: Dimensions, physical properties and magnetic properties GB/T15131.3130mm floppy disks with a bit density of 13262 flux turns/radian and 80 tracks per side for information processing data exchange Part 3: Track format B (for 80 tracks) GB/T15134 File structure and numbering of floppy disks for information exchange in information processing systems 4 General requirements
4.1 Recording method
4.1.10 side 00 track
The recording method is a dual frequency system, in which the beginning of each bit unit is a clock flux turn. A data flux turn between two clock flux turns represents "1".
Exceptions to the provisions in 4.12.
4.1.2 All tracks except track 00 on side 0 are recorded in modified frequency modulation (MFM). The conditions are: a. Write a flux reversal at the center of each bit cell containing "1"; b. Write a flux reversal at each cell boundary between consecutive bit cells containing "0". Exceptions are made to the provisions in 4.12. 4.2 Track position tolerance of recorded floppy disks Under the full range of environmental conditions specified in GB/T15131.1, the center line of the recorded track should be within ±0.0425mm of the nominal position.
4.3 Recording deviation angle
At the moment of writing or reading a flux reversal, the flux reversal may have an angle of 0°±18° with the radial direction. Note: Since the tracks may be written or rewritten at the tolerance limits given in 4.2 and 4.3, part of the original information may remain on one side of the newly written data, causing unwanted noise when reading. Therefore, it is necessary to use the write-after-erase method to trim the track edges. 4.4 Recording Density
4.4.1 The nominal recording density is 13262 flux reversals/radian. The nominal bit cell length of the 00 track on the 0 side is 151urad, and the nominal bit cell length of all other tracks is 75.5urad. 4.4.2 The average bit cell length of the long term shall be the average of the bit cell lengths measured over the entire sector. It shall be within ±2.0% of the nominal bit cell length.
4.4.3 The average bit cell length of the short term (relative to a particular bit cell) shall be the average of the lengths of the preceding 8 bit cells. It shall be within ±8% of the average bit cell length of the long term. 4.5 Flux Reversal Spacing
The instantaneous spacing between flux reversals is affected by the read and write processes, the order of the recorded bits (pulse crowding effect), and other factors. The position of the reversal is defined as the position of the signal peak during readout. The test is performed using a peak sense amplifier [see Appendix B (reference) and Appendix C reference gate.
4.5.10-plane 00 track flux reversal spacing (see Figure 1) 437
90%~140%
GB/T 15131.2-1995
90% ~140%
4.5.1.1 The spacing between two clock flux reversals containing a data flux reversal or the spacing between two data flux reversals containing a clock flux reversal shall be 90%~140% of the nominal bit unit length. 4.5.1.2 The spacing between two clock flux reversals without data flux reversals or the spacing between two data flux reversals when there is a leakage clock flux reversal shall be 60%~110% of the nominal bit unit length. 4.5.1.3 The spacing between a data flux flip and the preceding clock flux flip (when there is no shortage) or the spacing between a clock flux flip and the preceding data flux flip (when there is no shortage) shall be 45% to 70% of the nominal bit unit length. 4.5.2 The flux flip spacing of all tracks except the 00 track on the 0 side (see Figure 2) 0
80% ~120%
130% -165%
130%~165%
185%~2259%
4.5.2.1 The spacing between consecutive "1" flux flips shall be 80% to 120% of the average bit unit length of the short term. 4.5.2.2 The distance between the flux reversal between two "0\" and the flux reversal before it or after it should be 130% to 165% of the average bit unit length of the short term.
4.5.2.3 When there is only one "0" bit unit between two "1", the distance between the flux reversals of two "1" should be 185% to 225% of the average bit unit length of the short term.
4.6 Average signal amplitude
The average signal amplitude on any defect-free track (see GB/T15131.1) on each side of a floppy disk for data exchange The signal amplitude should be less than 160% of the standard reference amplitude SRAr of 1f and greater than 40% of the standard reference amplitude SRA2 of 2f. 4.7 Bytes
A byte is a combination of 8-bit positions, identified by B1 to B8, where B8 is the most significant bit and is recorded first. The bit at each position should be "0" or "1". 4.8 Sectors
Track 00 on side 0 and side 1 is divided into 26 sectors. All other tracks of the floppy disk have the same number of sectors, which can be 8, 15 or 26.
4.9 Cylinders
GB/T 15131.2-—1995
A pair of tracks with the same track number (there is one track on each side of the disk). 4.10 Cylinder number
The cylinder number is represented by two digits and is the same as the track number of the track on the cylinder. Data capacity of one track
The data capacity of track 00 on side 0 is 3328 bytes. The data capacity of track 00 on side 1 is 6656 bytes. The data capacity of all other tracks is shown in Table 1. Table 1
Number of sectors
4.12 Hexadecimal notation
The following bytes are represented by hexadecimal notation: (00) represents (B8～B1) = 00000000
(01) represents (B8～B1) = 00000001
(02) represents (B8～B1) = 00000010
(03) represents (B8～B1) = 00000011
(FF) represents (B8～B1) = 11111111
(FC)* represents (B8～B1) = 11111100
Among them, B6 and B4 have no clock flip.
(FE)\ represents (B8～B1)=11111110
, among which B6, B5 and B4 have no clock flip. (FB)* represents (B8～B1)=11111011
, among which B6, B5 and B4 have no clock flip. (F8) represents (B8～B1)=11111000
, among which B6, B5 and B4 have no clock flip. (4E) represents (B8～B1)=01001110
(FC) represents (B8～B1)=11111100
(FE) represents (B8～B1)=11111110
(FB) represents (B8B1)=11111011
(F8) represents (B8～B1)=11111000
(A1)* represents (B8～B1)=10100001
There is no boundary flip between B3 and B4. (C2)* represents (B8～B1)=11000010
There is no boundary flip between B4 and B5. 4.13 Error Check Character (EDC)
Number of data bytes in a sector
Capacity of a track
6656 bytes
7680 bytes
8192 bytes
Two EDC bytes are generated by hardware, that is, by serial shifting the relevant bits (see the following definition of each part of the track) through a 16-bit shift register [see Appendix A (Reference)]. Its generating polynomial is: X16 + X12 + X5 + 1
GB/T15131.2-1995
5 Track configuration of track 0 on side 0 after first formatting Track 0 on side 0 after first formatting should have 26 usable sectors. The track configuration is shown in Figure 3. Index gap
5.1 Index gap
Sector identifier
Identifier gap!
1st sector
This field nominally includes 73 bytes. 1st
Data block
There are no other requirements except that the content cannot contain (FE)* bytes. Data block| |tt||Data Block
Data Block
Finally Sector
Increase IntervalbZxz.net
Writing the index gap begins when the index window is detected. Any of the first 20 bytes may be undefined due to subsequent rewriting.
5.2 Sector Identifier
This field is shown in Table 2.
Identifier Tag
6 Bytes
5.2.1 Identifier Tag
1 Byte
This field consists of 7 bytes:
6 (00) bytes||tt ||1 (FE)* byte.
5.2.2 Address Identifier
This field consists of 6 bytes.
5.2.2.1 Track Address
This field consists of 2 bytes:
a. Cylinder Address (C)
Track Address
1 byte
1 byte
Address Identifier
1 byte
This field represents the cylinder address in binary notation, which is (00) in all sectors. b. Surface Number (Surface)
This word The sector represents the surface of the disk. It is (00) in all sectors. 5.2.2.2 Sector number (S)
1 byte
2 bytes
The third byte represents the sector number in binary notation, which starts from 01 for the first sector and ends at 26 for the last sector. 140
The 26 sectors are recorded in natural number order as follows: 1, 2, 3, ..., 25, 26
5.2.2.3 The fourth byte of the address identifier The fourth byte is always a (00) byte. 5.2.2.4 EDC
GB/T 15131.2--1995
These two bytes shall be generated according to the provisions of Section 4.13 using the sector identifier bytes starting from the (FE) byte of the identifier mark (see Section 5.2.1) and ending at the fourth byte of the address identifier (see Section 5.2.2.3). 5.3 Identifier Slot
This field consists of 11 initially recorded (FF) bytes. 5.4 Data Block
This field is shown in Table 3.
Data Tag
6 bytes
5.4.1 Data Tag
This field consists of 7 bytes:
6 (00) bytes;
1 (FB)* byte.
5.4.2 Data Field
Data Field
1 byte
128 bytes
2 bytes
This field consists of 128 bytes. The content of this field (see clause 7.4.2.4.2) has no requirements other than the correct EDC. 5.4.3 EDC
These two bytes shall be generated as specified in 4.13 using the data block bytes starting from the seventh byte of the data marker (see 5.4.1) and ending with the last byte of the data field (see 5.4.2). 5.5 Data Block Gap
This field consists of 27 initially recorded (FF) bytes. It is recorded after each data block and before the next sector identifier. The data block gap after the last data block is before the track gap. 5.6 Track Gap
This field shall follow the data block gap of the 26th sector. At nominal recording density, it shall consist of 247 (FF) bytes writing the track gap until an index hole is detected, unless an index hole is detected when writing the last data block gap, in which case there shall be no track gap.
6 Track configuration of all tracks except track 00 on side 0 after first formatting After each formatting, the number of sectors is determined by the sector length byte of the address identifier (see 6.2.2.3). The track configuration of each track is shown in Figure 4. Note: Track 00 on side 1 is always recorded as 26 sectors (see 4.8). 441
Index Gap
6.1 Index Gap
Sector Identifier
GB/T15131.2—1995
Identifier Gap
1st Sector
This field nominally contains 146 bytes. First
Data Block
Data Block
There are no other requirements for the content of this field except that it cannot contain the "(A1)" byte. Last
Data Block
Data Block
Last Sector
Track Gap
The index gap is written when the index window is detected. Due to subsequent rewriting, any of the first 40 bytes may be uncertain. 6.2 Sector Identifier
This field is shown in Table 4 .
Identifier Tag
12 bytes
3 bytes
6.2.1 Identifier Tag
1 byte
This field consists of 16 bytes:
12 (00) bytes,
3 (A1)* bytes;
1 (FE) byte.
6.2.2 Address Identifier
This field consists of 6 bytes.
6.2.2.1 Track address
This field consists of 2 bytes:
Track address
1 byte
1 byte
(00) or (01)
Address identifier
1 byte
1 byte
2 bytes
Cylinder address (C)
This field represents the cylinder address in binary notation, which is numbered sequentially from the outermost 00 cylinder to the innermost 74 cylinder. b, Surface number (Surface)
This field indicates the surface of the disk. On surface 0, the surface number is (00) on all tracks. On surface 1, the surface number is (01) on all tracks.
6.2.2.2 Sector Number (S)
The third byte represents the sector number in binary notation, from 01 for the first sector to the last sector (8, 15 or 26). These sectors are recorded in natural number order as follows: 442
1, 2, 3, until the last sector.
6.2.2.3 Sector Length (SL)
GB/T 15131.2-..1995
This field should be one of three values ​​(see Table 5), which determines the number of bytes in the data field and the number of sectors in the track. This value is the same for all sectors on the track, thus determining the number of sectors in the track. Only 26 sectors of 256 data bytes are allowed on track 00 on side 1, therefore, only (01) bytes are allowed in this field of the track.
Hexadecimal (SL) value
6.2.2.4 EDC
Number of bytes in the data field
Number of sectors in the track
These two bytes shall be generated as specified in 4.13 using the sector identifier bytes starting from the first byte of the identifier marker (A1)* byte (see 6.2.1) and ending with the sector length byte of the address identifier (see 6.2.2.3). 6.3 Identifier gap
This sector consists of 22 initially recorded (4E) bytes. 6.4 Data block
This field is shown in Table 6.
Data Tag
12 bytes
6.4.1 Data Tag
This field contains:
12 (00) bytes;
3 (A1)* bytes;
1 (FB) byte.
6.4.2 Data Field
3 bytes
1 byte
Data Field
2 bytes
The number of bytes included in this field is determined by the Sector Length byte in the Address Identifier (see 6.2.2.3). There are no other requirements for the content of this byte (see 7.4.2.4.2) except for the correct EDC. 6.4.3EDC
These two bytes shall be generated according to the provisions of 4.13 using the data block bytes starting from the first (A1)* byte of the data marker (see 6.4.1) and ending with the last byte of the data field (see 6.4.2). 6.5 Data Block Gap
This field includes a number of initially recorded (4E) bytes. The number depends on the number of bytes in the data field (see 6.4.2), as shown in Table 7.
Number of Data Field Bytes
GB/T 15131.2-1995
Number of Data Block Gap Bytes
This field 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.
6.6 Track Gap
This field is immediately after the data block gap of the last sector. It shall include a number of initially recorded (4E) bytes. At nominal density, the number depends on the number of bytes in the data field (see 6.4.2), as shown in Table 8. Table 8
Number of bytes in the data field
Number of bytes in the data block gap
Write the track gap until the index window is detected, unless the index window is retrieved when the last data block gap is written, in which case there should be no track gap.
7 Track configuration of recorded floppy disks for data interchange 7.1 Character representation
Characters should be represented by the seven-bit coded character set (see GB 1988), the extension of the seven-bit coded character set (see GB 2311) or the eight-bit coded character set (see GB 11383) when necessary. Each seven-bit coded character should be recorded in the B7 to B1 position of a byte. The B8 position should record "0". The relationship is shown in Table 9.
Position of the seven-bit combination
Byte bit position
Position of the B8 to B1 position of a byte.
Each 8-bit coded character should be recorded in
The relationship is shown in Table 10.
Bits of 8-bit combination
Byte bit position
7.2 Good cylinders and bad cylinders
A good cylinder is two tracks formatted according to 7.4. …A bad cylinder is two tracks formatted according to 7.5. 444
7.3 Requirements for cylinders
GB/T 15131.2--1995
Cylinder 00 should be a good cylinder. There are at least 74 good cylinders between cylinder 01 and cylinder 76. 7.4 Track configuration of good cylinders
Plate 00 track refers to Chapter 5. The remaining tracks refer to Chapter 6. 7.4.1 Index gap
For explanation, see 5.1 and 6.1.
7.4.2 Sector Identifier
7.4.2.1 Identifier
For explanation, see Sections 5.2.1 and 6.2.1.
7.4.2.2 Address Identifier
This field shall consist of 6 bytes.
7.4.2.2.1 Track Address
This field shall consist of 2 bytes.
a. Cylinder Address (C)
This field shall represent the cylinder address in binary notation, which is numbered sequentially from the outermost cylinder 00 to the innermost cylinder 74. Note: Each cylinder has a unique cylinder serial number (see Section 4.10). Two of these cylinders can be used only when one or two defective cylinders are present. Each good cylinder occupies a unique cylinder address; defective cylinders do not occupy cylinder addresses. The cylinder addresses for good cylinders are given consecutively in the increasing order of the cylinder serial numbers.
Surface number (Surface)
For description, see clauses 5.2.2.1 and 6.2.2.1.
7.4.2.2.2 Sector number (S)
For description, see clauses 5.2.2.2 and 6.2.2.2.
7.4.2.2.3 Fourth byte of address identifier
For description, see clauses 5.2.2.3 and 6.2.2.3.
7.4.2.2.4 EDC
For description, see clauses 5.2.2.4 and 6.2.2.4.
7.4.2.3 Identifier gap
For description, see clauses 5.3 and 6.3. Due to subsequent rewriting, these bytes may become indeterminate. 7.4.2.4 Data block
7.4.2.4.1 Data tag
For side 0 and track 00, this field includes: 6 (00) bytes;
1 byte.
The seventh byte should be:
(FB)" indicates that the data is valid and the entire data field can be read; (B8) indicates that the first byte of the data field can be read and interpreted according to GB/T15134. For all other tracks, this field includes: 12 (00) bytes;
3 (A1)* bytes;
1 byte.
The sixteenth byte should be:
(FB) indicates that the data is valid and the entire data field can be read; (B8) indicates that the first byte of the data field can be read and interpreted according to GB/T15134. 445
7.4.2.4.2 Data field
GB/T 15131.2--1995
The number of bytes included in this field is determined by Sections 5.4.2 and 6.4.2. If the number of bytes included is less than the specified number of bytes, the remaining portion is padded with (00) bytes. The data field of cylinder 00 is used by the operating system and labels. 7.4.2.4.3 EDC
See Sections 5.4.3 and 6.4.3 for explanation.
When the sector contains a defective area, if the last byte of the data mark is (F8)* or (F8) and the first character of the data field is an uppercase F, then the EDC may or may not be correct. If the first character is an uppercase D, then the EDC should be correct.
Only uppercase D is allowed on cylinder 00. 7.4.2.5 Data Block Gap
This field 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.
It includes 27 initially recorded (FF) bytes (see 5.5) or several initially recorded (4E) bytes (see 6.5). These bytes may become uncertain due to subsequent rewriting. 7.4.2.6 Track Gap
For explanation, see 5.6 and 6.6.
7.5 Track Configuration of Bad Cylinder
7.5.1 Field Contents
The fields of the two tracks of the bad cylinder shall have the following contents. 7.5.1.1 Index Gap
This field includes 146 (4E) bytes. 7.5.1.2 Sector Identifier
This field includes 1 identifier tag and 1 address identifier. 7.5.1.2.1 Identifier Tag
This field consists of 16 bytes.
12 (00) bytes;
3 (A1)* bytes;
1 (FE) byte.
7.5.1.2.2 Address Identifier
This field consists of 6 bytes:
4 (FF) bytes;
2 EDC bytes.
The two EDC bytes shall be generated as specified in clause 4.13 using the sector identifier bytes starting from the first (A1)* byte of the Identifier Tag (see clause 7.5.1.2.1) and ending with the above 4 (FF) bytes. 7.5.1.3 Remaining Fields
The contents of the remaining fields are unspecified and may be undefined. 7.5.2 Requirements for tracks
Each track of a bad cylinder shall have at least one sector identifier with the content specified in 7.5.1.2. If this condition is not met, the disk shall be rejected.
GB/T 15131.2--1995
Appendix A
EDC execution process
(reference)
Figure A1 is a feedback connection block 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". Add the input data to the stored value of C1s of the register (XOR) to form feedback. This feedback signal is then XORed with the stored values ​​of C and C in turn. During shifting, the output of the XOR gate is sent to C, Cs, and C12 respectively. When the last data bit is added, the register is shifted once more according to the above provisions.
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 exclusive OR operation. In order to detect errors 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 storage number of the shift register will be all "o\.
Input and Output
(tjEDC)
Appendix B
Procedure and Equipment for Measuring Flux Reversal Spacing (Reference)
B1 General Description
This appendix specifies the procedure and equipment for measuring the flux reversal spacing on a double-sided floppy disk with a density of 13262 flux reversals/radian recorded in a 130mm modified frequency modulation system.
B2 Format
The disk to be tested should be written by a disk drive for data exchange. Test on tracks 00 and 76 on both sides. Repeat the test pattern 00100000 (20) and 11101111 (EF) on track 00 on side 0. Repeat the test pattern 11011011 (DB) and 11011100 (DC) on all other test tracks. B3 Test Equipment
B3.1 Disk Drive
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