1. 2/8 The Floppy Drive Roll call Video: floppy drive Step-by-step lecture

2. Watch the Video Two parts.

3. 1: A floppy disk goes in The disk presses against a system of levers. One lever opens the shutter to expose the cookie. lever shutter

4. 1A: What’s a cookie? The cookie is a piece of Mylar (plastic) with a magnetic coating on both sides.

5. 2. The heads are positioned. Other levers and gears move the read/write heads into position, almost touching the cookie. Read/write heads

6. 2A: The read/write heads. Electromagnets that can read or write data to the diskette.

7. 3. Controlling movement: spin The shaft is run by the drive’s controller board. The shaft engages the disk’s hub via the notch to spin it. shaft notch in hub

8. 4. Controlling moves: read/write heads The controller board runs a stepper motor, which rotates to slide the heads back and forth. Stepper motor

9. 5. Reading from a diskette The diskette has magnetically coded data stored on it. Data is binary (1 or 0, on or off, north or south)

10. 5A. Reading from a diskette The read/write heads are electromagnets. To read, the magnetic signal on the disk influences the core of the head. core coil

11. 5B. Reading from a diskette The magnetic force creates a slight electric charge that travels up one of the two wires.

12. 5C. Reading from a diskette The head moves to the next band. If the polarities match, the resulting bit is a 0. If it is opposite, it is a 1. 0 1

13. 5D. Reading from a diskette The next bit always starts with opposite polarity. 01 1st bit2nd bit 3rd bit 0

14. 6. Writing to a diskette: can it be done? A diode and light sensor combo checks. If the light can pass, the disk cannot be written to. If it is blocked, the disk can be written to.

15. 6A. Writing to a diskette Reverse the order to write to a diskette (wire - coil - core - disk ).

16. 6B. Writing to a diskette Reverse the order to write to a diskette (wire - coil - core - disk ). Draw 1001 for a diskette 0101 1st bit2nd bit3rd bit4th bit