Clock rate (kHz or k) has nothing to do with the data rate or transfer rate (kBit/s or kbps). In other words, the cell timing is 4µs(period) MFM or 8µs(period) FM. In other words, the cell timing is 2µs(period) MFM or 4µs(period) FM. The clock rate (frequency) on 8" (and 5.25" 1.2 MB high density) floppies is always 500 kHz.
Top 8 inch and 5.25" 1.2 MB (high density) drives always spin with 360 revolutions per minute (rpm, r/m) or 60 revolutions per second (rps, r/s) or 166,67 milliseconds per revolution (ms/r). For this reason you can replace an 8" drive with an 1.2MB 5.25" HD drive. Clock rate and revolutions per minute are the same. In this table you can also see very well why 8 inch and 1.2 MB (high density) drives are very comparable. There is a bit of floppy maths in lines A to I. commands do not support 8-inch formats because 77 tracks and 128 or 1.024 bytes/sector are NOT supported, only 512 bytes/sector! Floppy disk formats supported by MS-DOSĪnd here is a pdf version of the DOS floppy disk formats. In KB-Q75131 three 8 inch formats are mentioned, but these formats were never used in IBM PC, XT, AT or compatible computers and were not supported by IBM PC compatible computers. MS-DOS already existed (long) before the first IBM PC (with PC-DOS) came onto the market! MS-DOS 2.0 ran, for example, on the NEC APC, which has two 8 inch drives. Note: If a format is supported by MS-DOS, this does not automatically mean that it is also supported by IBM PC-DOS. The official "Standard Floppy Disk Formats Supported by MS-DOS" are listed in the Microsoft Knowledge Base (KB) Article Q75131.
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