In FM encoding, each bit of data is divided into two distinct parts: a clock signal and a data signal. The clock signal is always present to indicate the timing, while the data signal only appears when the bit is a 1, and remains absent when the bit is a 0.
This constant clock pulse ensures that the floppy disk controller (FDC) always knows where each bit begins and ends. For every bit of information written to the disk, there’s always one clock signal and, if the data is a 1, a data signal as well.
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