The WD177X-00 is Floppy Disc Controller (FDC) IC family with 3 members with little differences. It can use single density (FM), or double density MFM modulation. The chips have an internal digital data separator and write precompensator circuits, eliminating the need for external passive components.
The WD1773 is fully software compatible with the earlier FD1793 FDC.
The WD1770/72 cannot detect the FDD Ready signal, but can control the motor of the FDD (motor spinup sequence).
The WD1772 has different FDD head stepping rates (2ms, 3ms, 6ms, 12ms) than the others (6ms, 12ms, 20ms, 30ms).
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