1.2.3/4 - Units & Data Storage

Question 1

How do you calculate data capacity?

Answer 1

Text file:
- Bits per character x Number of characters
Image file:
- Colour Depth x Image Height (pixels) x Image Width (pixels)
Sound file:
- Sample rate x Duration (s) x Bit Depth

Question 2

What are the units of data storage?

Answer 2

• Bits
• Nibble (4 bits)
• Byte (8 bits)
• Kilobyte (1000 bytes)
• Megabyte (1000KB)
• Gigabyte (1000MB)
• Terabyte (1000GB)
• Petabyte (1000TB)

Question 3

Why must data be stored in binary format?

Answer 3

• Computers use on/off signals
• Binary has two states : 0 and 1
• These states can represent the on/off signals

Question 4

List the Hexadecimal characters 10-15

Answer 4

10 - A
11 - B
12 - C
13 - C
14 - E
15 - F

Question 5

How do you convert Denary to Binary?

Answer 5

Use a binary number line

eg. 89 to Binary
128 64 32 16 8 4 2 1
0 1 0 1 1 0 0 1

Question 6

How do you convert Denary to Hexadecimal?

Answer 6

• Convert denary number to binary
• Group into 2 nibbles (groups of 4)
• Add up the nibbles then convert into the hex characters

eg. 230 to Hexadecimal
1 1 1 0 | 0 1 1 0
8 4 2 1 | 8 4 2 1
E 6

Question 7

How do you convert Hexadecimal to Denary?

Answer 7

• Turn each character into a nibble
• Binary -> Denary convert

eg. A6 to Denary
A = 10 | 6 = 6
1 0 1 0 | 0 1 1 0
128 + 32 + 4 + 2 = 166

Question 8

How do you add two Binary Integers together?

Answer 8

1 + 0 = 1
1 + 1 = 0 carry 1
1 + 1 + 1 = 1 carry 1

eg.
n | 0 0 1 1 1 0 1 1
n | 0 1 1 1 1 1 0 0
a | 1 0 1 1 0 1 1 1
c | 1 1 1 1

Question 9

How do you do a Binary Shift?

Answer 9

• Move the numbers to the left or right
• Denary number doubles when shifted left, halved when shifted right

eg. Left shift
0 0 1 1 0 1 0
0 1 1 0 1 0 0

Question 10

What are the Most/Least Significant Bits?

Answer 10

MSB : 128, represents biggest value
LSB : 1, represents the smallest value

Question 11

What is an Overflow Error?

Answer 11

• A binary 1 goes beyond the capacity of the storage line
• Max denary number - 255
• Have to add extra column to store numbers >255