Representation of Data in a Computer system

Question 1

What is a bit, nibble, byte, kilobyte, megabyte, gigabyte and terabyte?

Answer 1

a bit is a single digit in binary (0, 1), 4 bits, 8 bits, 1024 bytes, 1024 kilobytes, 1024 megabytes, 1024 gigabytes
You can say 1000 instead of 1024

Question 2

Why does data need to be converted to binary to be processed by a computer?

Answer 2

So the computer can understand what is being inputted in its own language as binary represent two states in a circuit (on/off)

Question 3

How do you convert denary into binary?

Answer 3

8 bit binary goes 128, 64, 32, 16, 8, 4, 2, 1 add them up to get denary

Question 4

How do you add binary?

Answer 4

1 + 1 = 10 write zero carry 1
1 + 1 + 1 write 1 carry 1
0 + 1 = 1
0 + 0 = 0
Or convert to denary

Question 5

What is an overflow error?

Answer 5

When a computer has only a certain number of bits to store a value and the result of addition needs and extra bit

Question 6

How do you convert denary into hexadecimal?

Answer 6

you divide by 16 and get the remainder for the second digit
then you divide again by 16 and get the remainder for the first digit
197 = C5

Question 7

How do you convery binary into hexadecimal?

Answer 7

split 8-bit binary into two four bits and represent the four bits in hexadecimal

Question 8

Why is hexadecimal used to represent binary numbers?

Answer 8

It is much easier to write, remember and communicate with

Question 9

How are binary codes used to represent characters?

Answer 9

relates a binary number with a character in a character set

Question 10

What is a character set?

Answer 10

The list of codes and matching characters

Question 11

What is the relation between the number of bits per character in a character set and the number of characters which can be represented?

Answer 11

The more bits per character the more numbers in a character set

Question 12

What is the ASCII character set?

Answer 12

It uses 7 bits so can provide 128 characters

Only uses the English alphabet

Question 13

What is the Unicode character set?

Answer 13

It uses 16 bits so can provide over 60,000 possibilities or 32 bit
It is universally applicable with many characters

Question 14

How are images represented?

Answer 14

as a series of pixels represented by binary

Question 15

What is the need for metadata to be included in a file?

Answer 15

metadeta shows the height, width, colour depth

Question 16

What is the effect of colour depth and resolution on the size of the image?

Answer 16

The colour depth is the number of bits per pixel

The resolution is the number of pixels

Question 17

How can sound be sampled and stored in a digital form?

Answer 17

Convert analogue waveform into a numerical representaion, the device is called Analogue-to-Digital converter (ADC)
It measures the amplitude of the waves at regular intervals (sampling) and stores the values as a series of binary numebers

Question 18

How does sample intervals and others considerations affect file size and quality of playback?

Answer 18

The smaller the sample interval the higher the sample rate (samples per unit of time)
This means that the file size is bigger but the quality is better as there is a better match between the original and sampled sound
Also sample resolution is the number of bits stored per sample

Question 19

How are instructions coded in bit patterns?

Answer 19

There is an op-code and number bit (operator) and the operand
0110 1101 (011 is the op-code, 0 is the number bit, 1101 is the operand)

Question 20

How does the computer distinguish between instructions and data?

Answer 20

The op-code codes for instructions, operand for data

Question 21

What is the op-code, number bit and operand?

Answer 21

The op-code stores the instruction
The number bit says whether it is a value or an address
The operand is data or an address