Floppy Drive 3 1/2 inches.

Floppy Drive 3 1/2 inches.

1 - When a floppy disk 3 1/2 inches is inserted into the drive, it pushes the drive lever system. A
lever opens the flap (shutter) of the disc to expose the cookie - the layer of Mylar covering the both disk
sides with magnetic material that allows the recording of data.

2 - The other levers and gears move the two heads read / write up to almost touch the disk surface
(Cookie) on both sides. The heads, which are tiny electromagnets, the magnetic pulses used to change the orientation
of the metal particles contained in the disc surface.

3 - The circuit board unit receives signals from the controller card, containing the data and the instructions for these
data is written to disk. The circuit board converts the instructions into signals that control the movement of the disc and
heads read / write.

4 - If the signs contain instructions for the data to be written to disk, the circuit board finds in the first
place if there is no light visible through the small window that can be closed, located in a corner of
housing floppy. If the window is open and the light beam emitted by the diode can be detected by the photodiode
located on the opposite side of the disc, the unit will recognize that the disc is protected and refuse to write the data.

5 - The engine located below the disk rotates a shaft which engages a tooth in the center hole of the disc to make it spin.

6 - A stepper motor - which can rotate a certain number of times in either direction, according to signals
received from circuit board - moves a second axis having a spiral groove. Inside this groove, there is an arm that
binds to the head read / write. As the shaft rotates, the arm moves forward and backward, placing the
heads read / write on the disc.

7 - When the heads are properly positioned electrical impulses create a magnetic field in one of the heads
write data to the top or bottom surface of the disk. When the heads are reading data, they react to
magnetic fields generated by the hard metal particles.

Note - Despite the differences in size and casing, the floppy 5 1/4 inches is just a bigger version, more
less complicated and slow disk 3 1/2 inches. It has no door to be opened, but has a cutout side
to determine if it is protected against data recording. The heads read / write drive work the same
so that the smaller unit.

Source: Evolution of Computers