Module 2 Software – Activities Activity 1

1. Many end-users are not really sure what an operating system is and why they even need one.

Give a concise (short, to-the-point) definition of what an operating is and give four typical functions of an operating system.

1. An operating system is system software which controls all the activities that take place in a computer.

Functions of an operating system

• 
  provides an interface
  
• 
  manages processes and tasks
  
• 
  manages memory
  
• 
  manages input and output
  
• 
  manages the disk/s etc.
  

2. OS X

3. Cost – Linux is free, unless you buy a packaged version, which will still be much cheaper than purchasing Wndows 8.

4. What operating system would you associate with versions such as Jelly Bean, KitKat and Ice Cream Sandwich?

4. Android

5. With which operating systems would you associate the following images/logos?

1. 
   (b)
   

6. What operating system would you typically find on devices such as the iPhone, iPod Touch or iPad?

6. iOS

7. What type of systems typically have Windows RT installed on them?

8. One of the essential functions of an operating system is process management.

What is process management?

8. Process management is the task of making sure that each process gets enough CPU time and access to memory, storage and other hardware so that it can work without interfering with, or being interfered with, by other processes.

9. The Task Manager in Windows shows a lot of useful data in terms of resources and processes that are currently running. The screenshot shows that there are 1103 threads active.

Briefly explain what a thread is and give an example.

9. A thread is a part of a larger program that runs independently but simultaneously with other parts of the same program.

Example: Threads allow a word processor to automatically check your spelling and grammar while you type.

10. Multitasking is when a computer runs or appears to run multiple programs at the same time.

Briefly explain how this is achieved in a system with a single core CPU.

10. The operating system splits the CPU time between the active programs and gives each program a few fractions of a second of access time to the CPU. Because this switching between programs happens so quickly, it appears to us that the computer is performing more than one task at the same time.

11. Can multitasking and multiprocessing take place in a computer system with a single CPU? Briefly motivate your answer.

11. Multitasking can take place with a single (or multiple) processor, and can be used to allocate CPU time to each of the active programs, so that it appears that the computer is performing more than one task at the same time.

Multiprocessing, however, only takes place when the operating system divides the programs or threads or processes between more than one physical CPU. (This includes CPUs with more than one core because each core is a CPU even if it is not on a separate chip).

1. A friend says she received an error message on her computer that warned her about ‘low virtual memory’.

Briefly explain what this message means by referring to the function of virtual memory.

1. When RAM becomes full, data is moved from RAM to space on the hard drive, known as virtual memory. The message is appearing as the free space on the hard drive for the virtual memory is running low.

2. Will increasing the size of virtual memory or adding more RAM be a better solution to the problem expressed in the previous question? Briefly motivate your answer.

2. Generally, the more RAM a computer has, the better it will perform (‘the faster it will run’). Accessing data from RAM is far quicker than accessing data from disk (virtual memory). In addition, the operating system has to swop data between the RAM and storage continually if memory is (RAM) is full – causing thrashing which further slows down the computer, so adding RAM is the better option.

3. Your friend took your advice and added another 4 GB of RAM to her system, but the computer only sees the ‘original’ 4GB of RAM she had installed.

Explain to her what the most likely cause of the problems is, assuming the RAM is not faulty and has been correctly installed.

3. She may have not have a 64-bit version of the operating system installed, which is needed if you want to access more than 4 GB of RAM.

Activity 3

1. Why is it less important for a program to be compatible with a processor than to be compatible with an operating system?

1. Operating systems have standardised access to hardware, so the program can hand over some tasks to the operating system as long as the software is compatible with the operating system. All the programs need to do is call the appropriate API or ‘routine’ of the operating system to perform the task.

2. When programs or apps are developed, you will often see separate versions – one for say Android and another one for iOS, etc. Why does the same program or app need to have different versions like this?

2. Each operating system is written with different features and has different ways of interfacing with it, so a different ‘version’ has to be written for each operating system platform.

3. Very few programmers will ever need to use low-level programming languages.

Explain what a low-level programming language is and give two situations in which a programmer might use such a language.

3. Low-level programs work directly with the CPU. Programs written in this way tend to be small, highly efficient and very fast. This type of programming is mainly used for producing high speed, efficient code needed when writing system (OS) software or when writing ‘embedded’ code that will control a dedicated device and that will produce a program that is small and fast.

4. Give two examples of a high-level programming language.

4. C++, C#, Delphi, Java, Python etc.

5. Compilers and interpreters differ only in the way they work, but they perform the same task. What is this task?

5. They convert a high-level programming language code into machine code that the CPU will understand.

6. How does a compiler differ from an interpreter in terms of how it works?

6. A compiler takes an entire program and translates it into machine language. A compiler examines the entire program and generates a list of any problems (‘errors’) that it encounters which might prevent it from successfully generating a set of machine code instructions. If the compilation is successful, the compiler will then create an executable file, also known as a standalone program.

An interpreter runs one line of a program at a time. This means that only the current line is converted into machine language as it is executed. Possible errors are not detected before the program is run and if the line contains an error, the program will crash.

7. Give two examples of interpreted languages.

7. Python, Java, Scratch etc.

Activity 4

1. Virtualisation is a common term in computers. This ranges from virtual memory to virtual reality. How are all these systems ‘implemented’.

1. They are created as virtual ‘objects’ using software.

2. List two main advantages of virtualisation

2. You will save money and time. You will increase the level of efficiency.

3. Give two examples of virtualisation software.

3. VirtualBox, Parallels, VM Player, etc.

4. Explain the difference between a host and a guest operating system in the context of virtualisation.

4. The host operating system is the original operating system installed on the computer. The guest operating systems are those than run as virtual operating systems on the computer.

5. How does the concept of a virtual machine get around the issue highlighted in Activity 3, Number 2?