Paper 2

Question 1

Algorithm

Answer 1

Algorithmic thinking is solving problems by defining the steps and the sequence needed.

Question 2

Abstraction

Answer 2

Abstraction is removing unnecessary detail from a problem.

Question 3

Decomposition

Answer 3

Decomposition is breaking a problem into sub- problems that each represent a specific task.

Question 4

High level advantage

Answer 4

• HIGH-LEVEL
• Like written English
• More readable
• Portable-can run on many CPUs
• Slower to execute

Question 5

Translator

Answer 5

It translates a high-level language program into a machine language program that the (CPU) can understand. It also detects errors in the program

Question 6

Compliers

Answer 6

High-level Machine code

-The whole program is validated so there are no system errors.
-The executable file is enhanced by the compiler, so it runs faster.
-User do not have to run the program on the same machine it was created.

Question 7

interpreter
adavantages

Answer 7

advantages
-You discover errors before you complete the program, so you learn from your mistakes.
-Program can be run before it is completed so you get partial results immediately.
-You can work on small parts of the program and link them later into a whole program.

Question 8

Interpreter disadvantages

Answer 8

disadvantages
Interpreted code runs slower than compiled code. the interpreter has to analyse and convert each line of source code into machine code before it can be executed.

-There’s a possibility of syntax errors on unverified scripts.
-Program is not enhanced and may encounter data errors.
-It may be slow because of the interpretation in every execution.

Question 9

truth table purpose

Answer 9

• To show all possible inputs (to the logic circuit)…
  *and the associated/dependent output (for each
  input)

Question 10

Give two ways that the maintainability of this program could be improved

Answer 10

-Use loop / iteration
-Add comments
-sequence

Question 11

advantages of merge sort

Answer 11

Merge individual elements into sorted lists of size 2
 Merge lists of size 2 into sorted lists of size 4
 Merge lists of size 4 into final sorted list.

Question 12

difference between function and producure

Answer 12

Function returns a value
 Procedure does not return a value

Question 13

advantages of sub programs

Answer 13

Easier to maintain
…as code is easier to understand/read
 …as code is shorter
Avoid repetition of code (in the same program)
 …makes program shorter / smaller
 … subprogram called instead of copying/pasting.
 … quicker to develop (new) programs

Question 14

2 defensive design

Answer 14

 Input sanitisation
 …cleaning up input data / removing unwanted data

 Validation
 …checking whether input data should be allowed / is
sensible / follows criteria

Question 15

difference between iterative and final testing

Answer 15

Iterative is during development // repeatedly testing
after/while making changes
* Final is when the development is (almost) complete //
done after iterative testing

Question 16

tools that the IDE provides

Answer 16

Editor
* to enable program code to be entered/edited

Translator / compiler / interpreter
* to convert the high level code into machine code /
* low level code / binary

Error diagnostics / debugging
* to display information about errors (syntax / runtime) / location of errors
* suggest solution.

Question 17

insertion sort difference

Answer 17

Insertion sort: * inserts/moves values into correct position * inserts value once (then in correct position)

Question 18

bubble sort difference

Answer 18

compares/swaps pairs of values
* value is repeatedly moved/swapped (until in correct position)
* repeats if a swap has been made // needs multiple passes