EN 28630-2-1992 pdf download.Information processing — Data interchange on 130 mm (5.25 in) flexible disk cartridges using modified frequency modulation recording at 13 262 ftprad, on 80 tracks each side Part 2: Track format A for 77 tracks.
This part of ESO 28630 specifies the quality of recorded signals, the track layout, and a track format to be used on 130 mm (5.25 in), 3 262 ftprad flexible disk cartridges intended for data interchange between data processing systems.
NOTE Numeric values in the SI and/or imperial measurement system in this part of ISO 8630 may have been rounded off and therefore are consistent with, but not exactly equal to, each other. Either system may be used. but the two should be neither intermixed nor re-converted. The original design was made using imperial units and further developments were made using SI units.
2 Conformance
A flexible disk cartridge shall be in conformance with ISO 863() when it meets all the requirements of parts 1 and 2 of ISO 8630 and when it implements one of the three sector sizes specified in 4.11. Data interchange is possible only when the interchange parties implement the same sector size.
NOTE ISO 7665 specifies a field in the volume label in which the implemented sector size is identified.
3 References
ISO 646. Information processing — ISO 7-bit coded character set for information interchange.
ISO 2022. Information processing — ISO 7-bit and 8-bit coded character sets — Code extension techniques.
ISO 4873. biforn at ion processing — ISO 8-bit code for information interchange — Structure and rules for implementation.
ISO 6429, Information processing — ISO 7-bit and 8-bit character sets — Additional control fit nctions for character-imaging devices.
Iso 7065-2, Information processing — Data interchange on 200 mm (8 in) flexible disk cartridges using modified frequency modulation recording at 13262 fiprad, 1,9 tpmm (48 Ipi), on both sides — Part 2: Track format.
ISO 7665, Information processing — File structure and labelling of flexible disk ca riridges for information interchange.
4 General requirements
4.1 Mode of recording
4.1.1 Track 00, side 0
The mode of recording shall he two-frequency where the start of every bit cell is a clock flux transition. A ONE is represented by a data flux transition between two clock flux transitions.
Exceptions to this are defined in 4.12.
4.1.2 All tracks excluding track 00, side 0 The mode of recording shall be Modified Frequency Modulation (M FM) for which the conditions are
a) a flux transition shall be written at the centre of each bit cell containing a ONE;
b) a flux transition shall be written at each cell boundary between consecutive bit cells containing ZEROs.
Exceptions to this are defined in 4.12.
4.2 Track location tolerance of the recorded flexible disk cartridge
The centrelines of the recorded tracks shall he within ± 0,042 5 mm (± 0.001 67 in) of the nominal positions, over the range of operating environment specified in Iso 8630-1.
4.3 Recording offset angle
At the instant of writing or reading a magnetic transition, the transition shall have an angle of 00 ± 18’ with the radius.
NOTE As tracks may be written and overwritten at extremes of the tolerances given in 4.2 and 4.3, a band of old information may be left at one edge of the newly written data and would constitute unwanted noise when reading. it is therefore necessary to trim the edges of the tracks by erasure after writing.
4.4 Density of recording
4.4.1 The nominal density of recording shall be 13 262 ftprad. The resulting nominal bit cell length for track 00, side 0 is 151 irad, and for all the other tracks it is 75,5 j.irad.
4.4.2 The long-term average bit cell length shall be the average bit cell length measured over a sector. It shall be within ± 2,0 % of the nominal bit cell length.
4.4.3 The short-term average bit cell length, referred to a particular bit cell, shall be the average of the lengths of the preceding eight bit cells. It shall be within ± 8 % of the long-term average bit cell length.
4.5 Flux transition spacing
The instantaneous spacing between flux transitions may he influenced by the reading and writing process, the bit sequence recorded (pulse crowding effects) and other factors.
The locations 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 read amplifier (see Annex B and Annex C).
4.5.1 Flux transition spacing for track 00, .side 0 (see Figure 1)
4.5.1.1 The spacing between two clock flux transitions surrounding a data flux transition or between two data flux transitions surrounding a clock flux transition shall be between 90 % and 140% of the nominal bit cell length.EN 28630-2-1992 pdf download.

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