Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

A Level Comp Sci Paper 1 > 1.4.1 Data Types > Flashcards

1.4.1 Data Types Flashcards

1
Q

What is a character set?

A
  • A defined list of characters recognised by the computer hardware and software, with each character being represented by a single number
  • Character sets are agreed standards for referring to all characters a computer uses
  • Includes upper/lower case symbols and punctuation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

How many unique binary numbers does 7 bits give?

A

128

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is ASCII?

A
  • American Standard Code Information Interchange became the accepted standard.
  • It was then extended from 7 bit to 8 bit - Extended ASCII
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

How many unique binary numbers with 8 bits?

A

256

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

An international, multilingual language character set needs to include:

A
  • Characters from every written language
  • Historical scripts
  • Emojis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is UNICODE?

A
  • Was originally 16 bit but is now 24 bit character set providing over 16 million characters
  • Writing 24 bits is slow, so hexadecimal is used instead
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Why don’t we use UNICODE all the time?

A
  • The ASCII Character set is an 8 bit character set, meaning each unique character in a file is represented by 8 1s or 0s
  • The Unicode Character set is 8, 16 or 32 bit character set depending on version, therefore each character is either 8, 16 or 32 1s or 0s
  • Text file stored using UNICODE can take up more space than ASCII
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Exam Question: What is meant by the character set of a computer?

A
  • Normally equates to the symbols on a keyboard/ digits/ letters
  • That can be represented/ interpreted/ understood by a computer
  • May include control characters
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Exam Question: Explain how codes are used to represent a character set?

A
  • Each symbol has a (binary) code / number
  • Which is unique
  • Number of bits used for 1 character = 1 byte
  • Example code: ASCII / UNICODE
  • Uses 8 bits/ 16 bits per character
  • Use of more bits for extended character set
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Exam Question: The character A in the ASCII character set is represented by the denary value 65. Write the binary representation for the ASCII character “H”. Show your working. (2)

A
  • If A is 65, H is 72
  • 72 in binary is 01001000
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Describe what is meant by the term ASCII ?(2)

A
  • American Standard Code for Information Interchange
  • A character set
  • Maps values to characters
  • Uses 7 bits/8bits per character
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Exam Question: Explain what is meant by the term UNICODE? (3)

A
  • Unicode is a character set
  • Mapping different binary values to characters
  • Each character is represented by 1-4 bytes
  • It supports a very large number of characters
  • It is backward compatible with ASCII
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are the 5 primitive data types?

A
  • Integer
  • Real/floating point
  • Character
  • String
  • Boolean
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is an integer and give an example?

A
  • A whole number
  • 23
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is a real/floating point and give an example?

A
  • A number with an integer and a fractional part
  • 12.65
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is a character and give an example?

A
  • A single alpha-numeric character
  • D
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is a string and give an example?

A
  • A sequence of alpha numeric characters
  • Hello
18
Q

What is Boolean and give an example?

A
  • Either TRUE or FALSE
  • FALSE
19
Q

How do you represent positive 11 in a 4 bit binary system?

A
  • 1011
20
Q

How do you represent 121 into binary?

A
  • 01111001
21
Q

What are the 2 ways to represent negative numbers in binary

A
  • Sign and Magnitude
  • Two’s complement
22
Q

How do you use sign and magnitude to represent a negative number in binary?

A
  • The most sig fig is used to represent the sign
  • 1 means the number is negative and 0 means the number is positive
23
Q

How would you convert -4 into binary using sign and magnitude?

A
  • Write out positive 4 in binary
  • Then change the MSB to 1
  • 10000010
24
Q

Why is Sign and magnitude not used often?

A
  • Largest number that can be represented using 8 bits is 127 due to using MSB as a sign bit much less than 255
  • Also harder to do calculations as some bits mean different things; some numbers and some signs
25
Q

How do you represent a negative number using Two’s complement?

A
  • To write it out as a positive number
  • Then starting from the right hand side, flip each bit and then add 1
26
Q

Convert -86 into binary using Two’s complement

A
  • Work out + 86: 01010110
  • Then flip: 10101001
  • And add 1: 10101010
27
Q

What is

  1. 0+0
  2. 0+1
  3. 1+1
  4. 1+1+1 ?
A
  1. 0
  2. 1
  3. 10
  4. 11
28
Q

How do you do Binary Addition?

A
  • Arrange them above each other
  • Start at Least Significant Bit and add the 1s and 0s
29
Q

How do you do Binary subtraction?

A
  • Same as binary addition but convert the number to be subtracted into a negative number using 2s complement
30
Q

Binary addition: What is 42+18

A

00111100

31
Q

Binary subtraction: What is 68 - 33

A
  • 00100011
32
Q

What are the different symbols used in hexadecimal and what do they mean?

A
  • 0 - 9 = 0 - 9
  • A=10, B = 11, C=12, D=13, E = 14, F = 15
33
Q

How do you convert the denary number 31 into hexadecimal?

A
  • 1F
34
Q

What are the steps of writing a number into floating point notation?

A
  • Convert the exponent into denary.
  • If the exponent is positive, move the decimal point to the right, if negative move decimal point to the left
  • Put column headings under and add the value
35
Q

How do you normalise a number - if positive?

A
  1. Convert exponent to denary
  2. Move decimal point so it is before the first 1
  3. Subtract the number of moves from the exponent
36
Q

How do you add floating point numbers?

A
  1. The exponents of the 2 numbers must be the same
  2. Change the exponent of the 2nd number to the first exponent and adjust mantissa
  3. Add mantissas using usual method
37
Q

Add Mantissa: 01110, Exponent 010 and Mantissa 01000, Exponent 001 together?

A
  • 10010 010
38
Q

How do you subtract floating numbers?

A
  1. Just like addition, exponents must be the same and adjust mantissa
  2. Now convert the mantissa of the second number to a negative one using 2s complement
  3. Add the mantissas
39
Q

Subtract
Mantissa: 01110, Exponent: 010

from

Mantissa: 01000, Exponent 001

A
  • 01010 010
40
Q

What is Bitwise Manipulation and masks?

A
  • Bitwise Manipulation means applying logical operators (AND, OR, NOT, XOR) to binary
  • Mask is simply data being used in the operation
41
Q

How do you carry out Bitwise Manipulation?

A
  • Apply operations to corresponding bits
  • A = 10111001
  • B = 00111010
  • AND = 00111000

A Level Comp Sci Paper 1 (16 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions