Week 1

Question 1

What is OOP

Answer 1

Object-orientated programming is concerned with constructing computer systems out of units of code called classes which are templates for creating objects.

Question 2

what is the OS resposnsible for?

Answer 2

The operating System is responsible for the control and management of hardware and basic system operations, as well as running application software.

Question 3

What are 7 of the things the OS does?

Answer 3

Management of memory Coordination and control of peripheral devices Scheduling of access to the processor Provision of basic utilities Provision of an interface between applications/programs and hardware Provision of a user interface Booting your computer

Question 4

How does the OS manage memory?

Answer 4

it allocates appropriately sized areas of memory to each program and to ensure that program instructions and date do not interfere with each other.

Question 5

How does the OS Coordinate and control peripheral devices?

Answer 5

The OS cooridnates the Input (from keyboards and Mouse) reading a file from a storage device, output to a display device and maintaining a connection to a network.

Question 6

How does the OS schedule access to the processor?

Answer 6

The OS priotises jobs to run and ensures that the processor is used efficiently. for example if the current program finishes then another program is given access to the processor.

Question 7

How does the OS provide basic utilities?

Answer 7

OS provide disk formatting facilities, file management systems and software installation wizards.

Question 8

How does the OS provide an interface between applications/programs and hardware?

Answer 8

The OS provides a an application programming interface (API) which is a set of high-level instructions ( a protocol) through which an application can talk to the OS to request services such as printing or sasving. so for example instead of a program asking the printer to print the program asks the OS to ask the printer to print. This helps with computers working across different computers.

Question 9

How does the OS provide a user interface?

Answer 9

Most Interfaces are GUI’s with hidden away text baed interfaces. GUI’s are more intuitive and easier to learn and use.

Question 10

How does the OS boot your computer?

Answer 10

there is a boot program stored in the computers ROM and is often called firmware. firmware consists of prorams that provide core functionality to a device that will not disappear when power is lost.

Question 11

What is the difference between a compiler and an interpreter?

Answer 11

a compiler will translate an entire program from source code to machine code, whilst an interpreter will only translate a line of code as and when required.

Question 12

What is bytecode?

Answer 12

It is an example of an intermediate code, which could be thought of as machine code for a virtual machine. Using this intermediate code means that code can be moved unchanged between different computer systems.

Question 13

what is the advantage to using a compilation model that makes use of virtual machines?

Answer 13

it ensures that the intermediate code, no matter on what machine it was compiled it can be translated for execution on many different computers, so long as each computer has the correct virtual machine.

Question 14

Why is Java software relatively portable between different platforms?

Answer 14

Java software is portable because it runs on a VM, and the JVM masks inherent differences between the underlying architectures and operating systems on different computer platforms. As long as you have a suitable JVM for a platform, you should be able to run Java software on that platform.

Question 15

What is/was procedural programming?

Answer 15

is so called because the program code gives a step-by-step procedure (i.e an algorithm) for solving ‘the problem’.

Question 16

What are two important aspects of of an object?

Answer 16

its attributes and its behaviour.

Question 17

define an objects attributes.

Answer 17

An attribute is some external property or characteristic of an object, for example a ‘patient’ object may have attributes such as condition, date admitted and medication.

Question 18

what is an objects behaviour?

Answer 18

each object has a set of messages that it understands, the action an object performs in response to a particular message is an example of behaviour. we also use term behavious to mean the collection of actions an object might carry out in response to all the messages it understands.

Question 19

what is an identifier?

Answer 19

its the name that is given to attributes in code, such as ‘credit limit’ in to ‘creditLimit’.

Question 20

define an object’s state.

Answer 20

This is the combined value of all the object’s attributes. For example the state of a bank account object could be the value of balancer and creditLimit.

Question 21

Why was the concept of Java Editions introduced?

Answer 21

To cater for the different needs of large international buisness systems running on extensive networks with many servers as opposed to software running on mobile phones with very limited hardware resources.

Question 22

What are the main reasons for Java’s popularity as a programming language? (5 reasons)

Answer 22

Familiarity of style to existing programmers. Platform independance (portability) - Java runs on a wide range of hardware platforms. Robustness - Java avoids many error-prone featrues of some other languages Security - by design, Java allows the coding of relatively secure applications. Object_orientation - Java was designed with Object-orientated programming in mind, and so provides all the benefits of this programming approach.

Question 23

in a Java statement what is a message and what is a receiver?

Answer 23

receiver frog1.left() message

Question 24

what is a message-send?

Answer 24

a code that is made up of a variable name, followed by a full stop and then a message.

Question 25

in the following code, indicate the message and the object receiving the message. frog2.brown()

Answer 25

The message brown() i ssent to the object referenced by the variable frog2 - this object is the receiver.

Question 26

describe a class and its instances

Answer 26

A class is like a blueprint or template for the creation of objects and ensures that all its instances have the same attributes, and are able to respond to the same set of messages in an identical manner.

Question 27

‘Instances of a given class have the same attributes.’ Explain this statement.

Answer 27

A class defines what attributes each instance of the class will have.

Question 28

What is a protocol? (regarding the Amphibian Microworld)

Answer 28

The list of messages any instance of the class Frog can understand. The protocol of a Frog object, as we know it so far, is left(), right(), green() and so on.

Question 29

Use the terms ‘class’ and ‘protocol’ to explain why a Frog object does not understand the message up() and down().

Answer 29

The class defines the set of messages (the protocol) an instance of the class understands. Frog objects are instances of class Frog and the protocol for this class does not include the messages up() and down().

Question 30

Describe an Object Diagram

Answer 30

Question 31

Why are the componenets of a domestic electrical system (such as plugs and light bulbs) a suitable ana;pgy for the ideal software industry?

Answer 31

It is a suitable analogy because the domestic electrical system depends on standard parts; you can exchange different makes of each component, such as a plug or a bulb (at least within one country), and the system will still work. As long as each component works as intended, its make is irrelevant.