U2T1 - Data Representation

Question 1

What is our number system? (2 names)

Answer 1

Denary number system (base 10)

Question 2

What number system do computers use?

What is it also known as?

Answer 2

Binary

The base 2 number system

Question 3

From right to left, how do the columns to show binary go?

Answer 3

1, 2, 4, 8, 16, 32, 64, 128.

Question 4

What is the highest number you can make in binary with 8 digits?

Answer 4

255

Question 5

Convert denary to binary…
42
146

Answer 5

00101010

10010010

Question 6

Convert binary to denary…
01101011
11100110

Answer 6

107

230

Question 7

What are 2 ways to show negative numbers in binary?

Answer 7

Ones complement + twos complement

Question 8

Describe ones complement…

Answer 8

Convert 1’s to 0’s and 0’s to 1’s.

Question 9

Find ones complement of…

01100011 (99)

Answer 9

10011100 (-99)

Question 10

Describe twos complement…

Answer 10

Convert to binary, invert 1’s and 0’s, add one.

Question 11

Using twos complement:

Convert -5 to binary.

Answer 11

0101
1010
1011 (-5)

Question 12

Convert 1111 to decimal using twos complement.

Answer 12

1111
0000
0001
= -1

Question 13

How might you find the highest number a set of bits could create?

Answer 13

2n - 1

Question 14

What is the bit position on the right hand side called?

What about the left?

Answer 14

Least significant bit (LSB)

Most significant bit (MSB)

Question 15

How might a bit be represented in a computer’s main memory?

Answer 15

Transistor switched on/off, capacitor charged/discharged etc.

Question 16

How is data transmitted over telephone/radio?
What about magnetic disks (floppy/hard)?
Audio CDs, CD-ROMs & DVDs?

Answer 16

High + low pitched tones for 1s & 0s.
Magnetic field on coated surface (North-South/South-North)
Optically, surface does/doesn’t reflect light.

Question 17

What is a bit?

Answer 17

A binary digit. (0 or 1)

Question 18

How many bits in a byte?

Answer 18

8

Question 19

How many bytes in a KB?

Answer 19

1024

Question 20

How many KB in a MB?
MB in a GB?
GB in a TB?

Answer 20

1024

Question 21

How many bytes in a megabyte?

Answer 21

1,048,576

Question 22

Typical size + price for:
Hard Drive
DVD
Flash Drive
External Hard Drive

Answer 22

1 - 5 TB, £40 - £150.
4.7GB, £10.
8 - 32 GB, £8 - £11.
1 TB, £50.

Question 23

What is a character?

Answer 23

A letter/digit/special character represent with bits and bytes.

Question 24

What does a character set contain? Examples?

Answer 24

Letters, digits, punctuation marks, ‘control characters’ which are non-printing & used for special purposes. E.g. ASCII & Unicode.

Question 25

What is ASCII?

Answer 25

American Standard Code for Information Interchange. 7 bit code representing 128 characters. Bits represents symbols + characters in ASCII. 8th bit is a parity digit for error checking. 96 displayable characters, 32 control codes, 8 bits would give a range of 255.

Question 26

What is Unicode?

Answer 26

A worldwide character standard which allows for interchange, processing & display of written texts of majority of languages of the modern world. 16 bit, 65536 characters.

Question 27

Why is data stored in binary?

Answer 27

It's either on or off

Question 28

What is a nibble?

Answer 28

4 bits, half a byte.

Question 29

What is a crumb?

Answer 29

2 bits