OPERATING SYSTEMS (OS) By the end of this lesson you will be able to explain: 1. What an OS is 2. The relationship between the OS & application programs 3. Alternative operating systems and platforms they run on

Operating Systems core software component  The operating system is the core software component of your computer interface between computer outside world  It performs many functions and is, in very basic terms, an interface between your computer and the outside world  A computer consists of several component parts including your monitor, keyboard, mouse, and other parts interface to these parts "drivers"  The operating system provides an interface to these parts using what is referred to as "drivers"  This is why sometimes when you install a new printer or other piece of hardware, your system will ask you to install more software called a driver

What does a driver do?  A driver is a specially written program which understands the operation of the device it interfaces to, such as:  a printer,  video card,  sound card or  CD ROM drive.  It translates commands from the operating system or user into commands understood by the component computer part it interfaces with.  It also translates responses from the component computer part back to responses that can be understood by the operating system, application program, or user.

Operating Systems  The diagram shows the interfaces between the operating system and the computer component

Other Operating System Functions  The operating system provides for several other functions including:  System tools  System tools (programs) used to monitor computer performance, debug problems, or maintain parts of the system set of libraries or functions  A set of libraries or functions which programs may use to perform specific tasks especially relating to interfacing with computer system components  The operating system makes these interfacing functions along with its other functions operate smoothly and these functions are mostly invisible to the user

Operating System Concerns computer program  An operating system is a computer program  Operating systems are written by human programmers who make mistakes  Therefore there can be errors in the code even though there may be some testing before the product is released  Some companies have better software quality control and testing than others so you may notice varying levels of quality from operating system to operating system

Operating System Concerns  Errors in operating systems cause three main types of problems:  System Crashes and Instabilities These can happen due to a software bug typically in the operating system This varies depending on the type of operating system system crash A system crash is the act of a system freezing and becoming unresponsive which would cause the user to need to reboot  Security Flaws Some software errors leave a door open for the system to be broken into by unauthorized intruders. As these flaws are discovered, unauthorized intruders may try to use these to gain illegal access to your system. Patching these flaws often will help keep your computer system secure. How this is done will be explained later. errors with some peripheral devices  Sometimes errors in the operating system will cause the computer not to work correctly with some peripheral devices such as printers.

Operating System Types  There are many types of operating systems Microsoft Windows  The most common is Microsoft Windows not  There are other worthwhile types of operating systems not made by Microsoft  The greatest problem with these operating systems lies in the fact that not as many application programs are written for them  However if you can get the type of application programs you are looking for, one of the other systems may be a good choice

Operating System Types  Examples of Operating Systems:  Windows  Windows - Windows 7 is the latest release of Microsoft Windows, a series of operating systems produced by Microsoft for use on personal computers  Unix  Unix - It is primary used to be a server rather than a workstation and should not be used by anyone who does not understand the system. It can be difficult to learn. Unix must normally run an a computer made by the same company that produces the software.  Linux  Linux - Linux is similar to Unix in operation but it is free. It also should not be used by anyone who does not understand the system and can be difficult to learn.  Mac O/S  Mac O/S - Most recent versions are based on Unix but it has a good graphical interface so it is both stable and easy to learn. One drawback to this system is that it can only be run on Apple produced hardware.

Questions 1. Name three main responsibilities of the operating system. 2. What is the purpose of a driver? 3. Why wouldn’t an OS have drivers for all peripheral devices pre-loaded? How do you obtain the driver if its not pre-loaded on your OS? 4. What two groups can software be divided into? Describe the relationship between the operating system and an application program running on a computer. 5. What are the three main errors caused by an OS? 6. Research and then provide a one or two sentence description of the 4 different operating systems outlined previously. You should talk about their main features, their history, their purpose and the platforms (hardware) they can operate on.

Answers 1. (1) Perform basic tasks, such as recognizing input from the keyboard, sending output to the display screen, keeping track of files and directories on the disk, and controlling peripheral devices such as disk drives and printers. (2) Ensure that different programs and users running at the same time do not interfere with each other. (3) Provide a software platform on top of which other programs (i.e., application software) can run. 2. A driver is a specially written program which understands the operation of the device it interfaces to. It translates commands from the operating system or user into commands understood by the component computer part it interfaces with. It also translates responses from the component computer part back to responses that can be understood by the operating system, application program, or user. 3. There are to many varieties of peripheral devices available on the market. If an OS came pre loaded with all drivers then this would take up a large amount of space. Peripherals generally come with a disk or drivers can be downloaded. 4. Software can be roughly divided into two groups: application software and system software. Operating systems are a type of system software that allow applications to interface with computer hardware. 5. System Crashes and Instabilities, Security Flaws, not to work correctly with some peripheral devices 6. Windows Unix Linux Mac O/S 6. Windows - Windows 7 is the latest release of Microsoft Windows, a series of operating systems produced by Microsoft for use on personal computers. Unix - It is primary used to be a server rather than a workstation and should not be used by anyone who does not understand the system. It can be difficult to learn. Unix must normally run an a computer made by the same company that produces the software. Linux - Linux is similar to Unix in operation but it is free. It also should not be used by anyone who does not understand the system and can be difficult to learn. Mac O/S - Most recent versions are based on Unix but it has a good graphical interface so it is both stable and easy to learn. One drawback to this system is that it can only be run on Apple produced hardware.