1.2.4 Introduction to programming

Question 1

Procedural programming paradigm

Answer 1

Procedural programming :
- Can be applied to wide range of problems
- Easy to write and interpret
- Program in Subroutines (functions and procedures)
- Subroutines carries out defined and specified steps to achieve output (uses sequence, selection and iteration)

Question 2

Object orientated programming paradigm

Answer 2

Object orientated : Can develop solution modelled on real world objects.
Advantages:
- Easier to update and maintain due to modular structure and classes can be modified or extended
- Encapsulation limits how attributes can be changed – debugging and security better.
- Improved re-usability of code – classes can be used in other programs and inheritance and polymorphism allow for re-usability
- Better coding for part of team – classes distributed between team members

Disadvantages :
- Where Few components reused - generally inefficient
- Generally Unsuitable for smaller problems

Question 3

Machine code

Answer 3

Binary code that the computer can execute
Each line Consists of Opcode (instruction) and Operand (data)

Question 4

High-Level languages

Answer 4

High Level languages :
- Closer to natural language / English –> easy to debug and build in team so faster development
- One instruction in high level can equate to many machine code instructions (one to many)
- Portable - Independent of processor architecture
- Translated with translator to machine code for different architectures.
- More abstracted - no knowledge of processor needed
- Come in many paradigms so can choose for problem.

Question 5

Low-Level languages

Answer 5

Low Level languages :
- Uses mnemonics
- One instruction equates to one machine code instruction –> can be much larger than high level. 1:1
- Fixed to processor architecture – not portable
- Translated with assembler
- More control over registers- more efficient with CPU resources and direct control of hardware and memory (through addressing modes)
- Useful for embedded processors where speed and efficiency important.
- but more knowledge needed of processor - longer to code

Question 6

Immediate addressing

Answer 6

Immediate addressing: Opcode acts on operand
- Data hard coded into instruction
- Nothing fetched from memory so very fast
- Value fixed at compilation so inflexible

Question 7

Direct addressing

Answer 7

Direct addressing: Operand is the memory location data is stored in
- Code refers directly to memory address of data
- Fast as RAM quickly accessible
- Flexible as value at address that is loaded can vary
- Limited on address range by size of operand

Question 8

Indirect addressing

Answer 8

Indirect Addressing : Operand gives address which holds address of where the data is located.
- Often used with libraries that get loaded into memory at run time, loader will likely place in different location in memory each time
- More flexible
- Increased address range as not limited by operand size.
- however multiple fetches required to access data.

Question 9

Modes of addressing

Answer 9

Opcode - Specifies instruction
Operand - Data instruction is to be performed on
Addressing mode specifies how the operand should be interpreted

Question 10

Indexed addressing

Answer 10

Indexed addressing : Operand is added to contents of Index Register (base address) to get memory location of value needed.
- Good for data that is stored contiguously such as in arrays.

Question 11

Object Orientated Programming (classes and objects)

Answer 11

Classes - Blueprint for object - constructor function instantiates object from class
- Defines attributes and methods implemented

Objects - Instance of a class
- Has attributes and methods tied to instance and not spread out.

Methods - Actions performed by object that link to procedures and functions

Attributes - Value held by object that link to variables

Question 12

OCR Syntax for OOP

Answer 12

Class dog()
Private name
Private colour
Public procedure new (MyName,MyColour)
name = MyName
colour = MyColour
Endprocedure

Question 13

Inheritance

Answer 13

Inheritance : Where a subclass / child inherits attributes and methods of parent class
- Reduces volume of code needed
- Can override methods of parent class and have own methods and attributes

Question 14

Polymorphism

Answer 14

Polymorphism : Where code can handle objects of different classes in the same way
and they can behave differently based on their class.
- Reduces volume of code needed and code can be more flexible

Question 15

Encapsulation

Answer 15

Encapsulation: When attribute is private (can only be accessed from within class)
- Only Public methods can be used to read / amend the attributes value.
- Can further validate inputs
- Objects only interact as intended and prevents unexpected changes to attributes having unforeseen consequences.
- Protects data from accidental changes - objects can only change in intended way - reduces chance of errors and inconsistencies.
- Likely fewer issues as the team combines their code .

Create getter and setter methods.
Setter is method that sets the value of an attribute
Getter is method that returns the value of an attribute

Question 16

Paradigm

Answer 16

A Paradigm is a way of thinking - programming languages come in and support many paradigms.
- Different problems suited to different paradigms that have advantages and limitations.