Magnetic storage: reading and writing with electromagnets

Name:

Date:

Class:

Quick Questions

Shade in the A or B circle for each question.

1. How does a magnetic drive store data on its platter?

A It magnetises tiny areas of the platter

B It burns pits into the platter with a laser

2. Which part of a magnetic drive writes and reads the data?

A The read/write head

B The transistor gate

3. In a magnetic drive, what do the magnetised areas of the platter stand for?

A The names of the files

B The 1s and 0s of binary data

4. How does the drive read data back from the platter?

A It detects the magnetic pattern on the platter

B It measures how much light bounces off the platter

5. What happens to the platter and the head while data is read or written?

A The platter stays still while the head spins

B The platter spins while the head moves across the tracks

Match the Pairs

Draw a line connecting each item on the left to its match on the right.

Left column		Right column
1read/write head		AA tiny area of the platter whose magnetic state stands for a binary 1 or 0
2magnetised area		Bhead.magnetise(area)
3To write data, the head uses an electromagnet to change the magnetic state of a tiny area of the platter		CThe platter spins while the head also moves across the tracks, so the head can reach different tracks of the platter.
4To read data, the head detects the magnetic pattern of the areas as the platter spins beneath it		DThis describes optical storage. A magnetic drive uses an electromagnet in the read/write head to magnetise tiny areas of the platter.
5A magnetic drive stores data by burning pits into the platter with a laser		EThe part that moves across the platter and uses an electromagnet to write data, or detects the magnetic pattern to read it
6The head stays still and only the platter moves, so one head position reaches all the data		Fpattern = head.detect(area)

Definitions

magnetise

Fill in the Blanks

Complete each line of code by filling in the missing parts.

WRITE: head uses an _____________

READ: head _______ the magnetic pattern

platter _____ while the head moves

Binary data: magnetic patterns for 1 and _

head moves across ______ on the platter

Spot the Error

Shade in the letter of the line that contains an error.

Question 1

A SPIN platter

B MOVE head TO track 4

C MAGNETISE area AS 9

Question 2

A STOP platter

B MOVE head TO track 2

C MAGNETISE area AS 0

Question 3

A SPIN platter

B MOVE platter TO track 3

C DETECT pattern IN area

D OUTPUT bit

Question 4

A USE laser IN head

B SPIN platter

C MAGNETISE area AS 1

Question 5

A SPIN platter

B MOVE head TO track 1

C count ← 0

D WHILE count > 8 DO

E MAGNETISE area AS bit

F count ← count + 1

Answer Key

Magnetic storage: reading and writing with electromagnets

Section A: Quick Questions

A — It magnetises tiny areas of the platter

A — The read/write head

B — The 1s and 0s of binary data

A — It detects the magnetic pattern on the platter

B — The platter spins while the head moves across the tracks

Section B: Match the Pairs

read/write head → The part that moves across the platter and uses an electromagnet to write data, or detects the magnetic pattern to read it

magnetised area → A tiny area of the platter whose magnetic state stands for a binary 1 or 0

To write data, the head uses an electromagnet to change the magnetic state of a tiny area of the platter → head.magnetise(area)

To read data, the head detects the magnetic pattern of the areas as the platter spins beneath it → pattern = head.detect(area)

A magnetic drive stores data by burning pits into the platter with a laser → This describes optical storage. A magnetic drive uses an electromagnet in the read/write head to magnetise tiny areas of the platter.

The head stays still and only the platter moves, so one head position reaches all the data → The platter spins while the head also moves across the tracks, so the head can reach different tracks of the platter.

Section C: Definitions

magnetise — A read/write head uses an electromagnet to magnetise tiny areas of the spinning platter to store 1s and 0s, and reads the data back by detecting the magnetic pattern.

Section D: Fill in the Blanks

WRITE: head uses an electromagnet

READ: head detects the magnetic pattern

platter spins while the head moves

Binary data: magnetic patterns for 1 and 0

head moves across tracks on the platter

Section E: Spot the Error

C — Magnetised areas only stand for binary data, so an area is set to 1 or 0. 9 is not a valid bit. It should be MAGNETISE area AS 1.

A — The platter must keep spinning so the areas pass under the read/write head. It should be SPIN platter.

B — The platter spins and the head moves across the tracks. The platter does not move to a track. It should be MOVE head TO track 3.

A — A magnetic drive head uses an electromagnet to magnetise areas. A laser is used in optical storage. It should be USE electromagnet IN head.

D — count starts at 0, so count > 8 is false at once and no areas are magnetised. To write 8 bits the condition should be count < 8.