Section 1

Question 1

Standard algorithms

Answer 1

• Input validation
• Running total in loop
• Traversing a 1D array

Question 2

Predefined Functions

Answer 2

• Round:
  Rounds numbers to certain no. of sig figs
  eg SET size TO ROUND (measurement, 2)
• Length:
  Returns the number of characters present in a value held in a variable
  eg SET numberOfCharacters TO LENGTH (firstname)
• Random:
  Returns random value in given parameters
  eg SET bonusBall TO RANDOM(1, 59)

Question 3

Storing real numbers

Answer 3

Stored using mantissa and exponent
mantissa x base ^ exponent

Question 4

Types of errors

Answer 4

• Syntax [eg misspelling]
• Logic [eg code out of order]
• Execution/run time [eg dividing by 0]

Question 5

Factors affecting readability

Answer 5

• Whitespace
• Meaningful variable names
• Internal commentary

Question 6

Logical operators

Answer 6

• AND
• OR
• NOT

Question 7

Storing vector graphics

Answer 7

Stored as a series of objects with a list of attributes
objects: square, ellipse
attributes: x- and y- coordinates, fill colour, length

Question 8

Storing bitmapped graphics

Answer 8

Stored as a grid of pixels, each with it’s own unique binary code

Question 9

Types of loops

Answer 9

conditional: keeps repeating until a condition is met.
eg while loops

unconditional/fixed: repeats a set number of times.
eg for loops

Question 10

Number of bits for an ASCII string

Answer 10

Each character is 1 byte (8 bits)

Question 11

Compiler

Answer 11

• translates source code into ‘object code’
• compiler is only held in RAM for the time that it takes to translate source code into object code
• translates lines one after the other but does not execute a line immediately after translation
• once created, object code can run independently of development environment and translator software
• if the object code file contains errors, the program will crash or cause unexpected output. Programmers must revisit source code, identify and correct errors and recompile
• used on finished, working programs

Question 12

Interpreter

Answer 12

• each line of source code is directly translated to machine code one at a time
• each line of code is executed as soon as it is translated
• interpreter software is present in main memory during each execution of program and execution of every line
• execution will stop immediately if the interpreter translates a line of source code that results in an error, and user will be notified
• used on unfinished programs

Question 13

Concatenation

Answer 13

The operation of joining character strings end-to-end

Question 14

Iteration

Answer 14

Returning to previous stages of the development process

Question 15

Methods to save energy

Answer 15

• settings on monitors
• power down settings (eg standby)
• leaving computers on standby

Question 16

Buses

Answer 16

Address bus:
- uni-directional, from the processor to RAM
- holds the address in RAM that the processor is accessing

Data bus:
- Bi-directional, between the processor and the memory

Question 17

Central Processing Unit

Answer 17

Handles the instructions used to ensure that hardware and software respond as expected. Tasks:
- fetch, decode and execute instructions from RAM
- perform arithmetic calculations
- perform logical operations
- control read, write, clock, interrupt and reset lines

Question 18

Arithmetic Logic Unit (ALU)

Answer 18

All calculations and logical decisions are handled by the ALU, eg storing real numbers. Tasks:
- performs all calculations
- performs comparisons on numeric values
- makes decisions based on logic (AND, OR, NOT)

Question 19

Registers

Answer 19

temporary storage locations within the processor. stores addresses, data or instructions

Question 20

RAM (Random Access Memory)

Answer 20

The processor can write to, or read from, RAM at high speed. RAM holds all the programs currently in use. Data can only be stored temporarily, all data in RAM is lost when the power is switched off

Question 21

ROM (Read Only Memory)

Answer 21

Data in ROM cannot be changed, this is fixed when the chip is manufactured. Data is stored permanently in ROM – it is not lost when the power is switched off

Question 22

ASCII

Answer 22

Stands for American Standard Code for Information Interchange
Each character (letter, number, symbol or control character) is represented by a binary value
Each character requires 1 byte (8 bits) of storage

Question 23

Malware

Answer 23

Short for malicious software. Types include:
* Viruses
* Trojans
* Worms
* Hacking
* Spyware
* Keylogger

Question 24

Firewalls

Answer 24

A program that helps stop hackers, viruses and worms from entering a computer over the internet. filters incoming and outgoing traffic. Only trusted users will be permitted access.

Question 25

Encryption

Answer 25

Data is scrambled so that it can only be understood by those with a key. Prevents hackers from being able to understand your data.

Question 26

Memory Addresses

Answer 26

The processor has to be able to pinpoint any storage location
needed so each storage location has its
own unique address

Question 27

Storing real numbers

Answer 27

mantissa x base^e

Question 28

Explain why it may be necessary to return to the design stage

Answer 28

• logic errors were found at a later
  stage
• new functionality is requested
• the program is not fit for purpose

Question 29

Why are predefined functions used

Answer 29

• no need to write code
• error free (no need to test)
• re-useable