Category Archives: Computing Higher

2. Software Development, Computing Higher

Types of Translator

The function of the translator is to change the source (program) code into object (machine) code.  There are two main types

  • Interpreter – This checks each line as it as typed for syntax errors. When the program is executed it is translated line by line and the resultant object code is stored in RAM while executed. The Interpreter needs to be present in memory while the program executes.
  • Compiler – This only checks for syntax error when the program is executed. The compiler changes the whole program to object code that is then stored on backing store where it can be executed without the compiler being loaded into RAM.
Computing Higher

Functions

A function is a sub program that returns a single piece of information. This makes it useful for mathematical operations as well as validation of inputs.

There two types of function

  • Predefined functions are built into the language. i.e.  Sin,Cos,Tan…
  • User Defined functions are created by the programer to aid in execution of a program.
Computing Higher

By Reference (ByRef) and By Value (ByVal)

This relates to the passing of parameters. A parameter is a variable that is passed into a sub program. It can be passed one of two ways.

  • ByVal – the sub program is given a copy of the data. This means that it can not pass any changes to it to the main program.
  • ByRef – the sub program is given the memory reference for the variable. This means that it can change the variable and that any changes will be passed back to the main program.

Rule of thumb ByVal=In, ByRef=Out

2. Software Development, Computing Higher

Local and Global Variables.

The main difference between these two types of variable is the scope in which they operate, this is called their domain.

  • Local variables – are only used within their own procedure. Changing them has no effect on the rest of the program.
  • Global variables – can be seen and changed from any part of the program. This means that they are quite resource intensive. If you finish working with the variable it will continue to take up space until the program exits.

Rule of thumb, Global variables are bad, okay!

More details.

2. Software Development, Computing Higher

Personel involved in the Software Development Process

The main people involved in the software development process are

  • Customer – This is who wants the software, they agree on the program specification the Analyst
  • Analyst – Their job is to find out what the customer wants, they do this by using questionnaires and interviews. The analyst produces the program specification which is the basis between the customer and the company developing the software.
  • Programmer – Their job is to take the spec. and turn it into a set of designs that can then be used to implement the final software solution. They can use a variety of languages and development environments.
  • Project manager – They are in overall change of the project. They are responsible for the budget and making sure the software is developed on time.
2. Software Development, Computing Higher, Homework

Homework – Language Type

Q1 Describe two features of a declarative language. (2)
Q2 Define an event in an event driven programming language. (1)
Q3 Describe a benefit of using a scripting language. (1)
Q4 Give a reason why there was a need for scripting languages to develop.(1)
Q5 A program can be compiled or interpreted to translate it from a high level language to machine code. Describe the difference between the two. (2)
Q6 Give an example of an object-oriented language and describe briefly how an object oriented language may work. (1)
Total Marks 10

Q1 Describe two features of a declarative language.2Q2 Define an event in an event driven programming language.1Q3 Describe a benefit of using a scripting language.1Q4 Give a reason why there was a need for scripting languages to develop.1Q5 A program can be compiled or interpreted to translate it from a high level languageto machine code. Describe the difference between the two.2Q6 Give an example of an object-oriented language and describe briefly how an objectorientedlanguage may work.1Total Marks 10

Computing Higher, Not in the exam

MS Office Pro Plus

So you are our trial section for this, as such you might lose access to the software at any time. Do not install this software on a machine that you already have MS Office on, there may be conflicts.

As part of our licence agreement with Microsoft, pupils can use MS Office 2013 Pro Plus for free on their own machines. To get access to this please follow the instructions below.

  1. Open Internet Explorer (Other browsers may work but I have only tested it on IE)
  2. Make sure you are not logged into any MS services, such as Glow or Hotmail.
  3. Go to http://portal.microsoft.com/
  4. Enter your school username followed by @nled.org.uk for the username i.e. 12315MadeupName@nled.org.uk
  5. Enter your school network password.
  6. Download and install the software.

Let me know how you get on.

2. Software Development, Computing Higher, Homework

Homework for Yesterday.

A few of you have lost the homework sheet. Here is an electronic version for you.

Evaluation

  1. What does “fit for purpose” mean and how can you evaluate it?  (2)
  2. What does “user interface” mean and how can you evaluate it?  (2)
  3. What does “readable” mean and how can you evaluate it?  (2)
  4. What does “robust” mean and how can you evaluate it? (2)
  5. What does “reliable” mean and how can you evaluate it? (2)
  6. What does “portable” mean and how can you evaluate it? (2)
  7. What does “efficient” mean and how can you evaluate it?  (2)
  8. What does “maintainable” mean and how can you evaluate it?  (2)

Design

Write an algorithm that gets a string from a user then displays it backward  (5)