FDD (Floppy Disk Drive) Control
The FDD consists of two sections: the FDD controller and the FDD module. The FDD
controller circuit controls the contents to be received and stores the data in the FDD
module. The FDD module drives the motors, sensors, and magnetic head. The
interface signals between the FDD and the FDC are shown in Table below:
Table.2.3 FDC(#5) and FDD Module Links (Interface Signals)
DRIVE SELECT Ø
This signal is set to LOW when the FDD unit is
opening (except for the DC Motor).
When this signal is set to LOW, data can be written
by the WRITE DATA signal. When this signal is set
to HIGH, the READ and STEP operations are
Data is written at the falling edge of this signal while
the WRITE GATE signal is LOW.
This signal indicates the polarity data read by the
This signal is used to select the head:
LOW: Head 1
HIGH: Head 0
This signal becomes LOW, starting the DC motor,
when a disk is set in the drive. Setting this signal to
HIGH or removing the disk stops the DC Motor.
This signal sets the head in the direction designated
by the DIRECTION signal.
This signal designates the movement of the
LOW: Inward to the disk's center
HIGH: Outward from the disk's center.
When this signal is LOW, either there is no disk in
the drive or the disk in the drive is write-protected.
This signal indicates the beginning of a track by
outputting one pulse in each rotation of the disk.
When this signal is LOW, the head is located at track
00 (the outside track).
Otherwise, the signal is HIGH.
When this signal is LOW, there is no disk in the drive.