All the computer components are linked together and pass information through the motherboard and CPU. It is a constant cycle of


Electronic components are joined together with hundreds of little microscopic pathways which carry electrical currents. Generally all motherboards include sound, video, and networking functionality.
Click here to see more information on the motherboard
By now you will have realised that a computer is basically a CPU, memory, and a lot of input and output devices. There is always a lot of data moving between these components.
The CPU is central in this relationship. All the data comes from input devices to the CPU. The CPU then directs it to memory, other parts of the
CPU, or to output devices. Every instruction and all data is controlled by the CPU.
Input Processing
Primary Memory
(RAM)
Keyboard
Mouse
Scanner
Central Processing Unit
(CPU)
Control Unit
Arithmetic
Logic Unit (ALU)
Computer
Program
Data
Secondary Storage
M e m o r y
Disk Drive
Registers
The CPU is central to the relationship between the components, and central to the flow of data/information between them.
Printer
Monitor u t
O u t p
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Unit 2783: Demonstrate knowledge of the components of personal computer systems
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Unit 2783: Demonstrate knowledge of the components of personal computer systems
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What is the relationship between the CPU, memory, input & output devices?
Describe the flow of information between them in the paragraph below by filling in the blanks using the words supplied. copy hard drive Output data CPU motherboard printer keyboard Input bus system processes RAM
When you type a letter using the computer the _________ acts as an
_________ device. The CPU _________ this raw _________ storing it temporarily in the_________. When you have finished you tell the computer to save the document in the _________. When you want a hard
_________ the _________ sends the instructions to the _________which acts as the _________device. The electronic messages travel to and from the CPU across the _________ to the other parts of the computer by the
_________.
Operating systems overview
Whenever you purchase a computer it usually has an operating system installed on its hard disk. This crucial piece of software (without which you can’t run a computer) includes many programs that control or maintain the operations of the computer and its devices. It enables communication between you the user, the application software and the computer’s hardware. The operating system is often referred to as the ‘ platform’ .
You may have heard people say, ‘what platform does your computer run on?” which simply means what operating system is your computer using.
Operating systems tasks
There are many different types of operating systems software and generally they all perform similar functions, such as:
 starting a computer
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Unit 2783: Demonstrate knowledge of the components of personal computer systems
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 providing a user interface
 managing programs
 managing memory
 coordinating tasks
 configuring devices
 establishing Internet connection
 monitoring performance
 providing file management utilities but some systems also allow a user to control a network and administer security.
Operating system location
In most computer set-ups, the operating system software is installed and operates on the hard disk/drive. For many mobile devices and handheld computers the operating system may reside on a chip.
Not all computer systems use the same operating system, for example, a mainframe computer does not use the same operating system as a personal computer. Not all desktop computers use the same operating system and some computers can even run multiple operating systems.
See next page for operating system functions.
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Unit 2783: Demonstrate knowledge of the components of personal computer systems
As already mentioned most operating systems provide similar functions; let’s look at their main functions:
Shelly, G.B., Vermaat, M.E. (2008) Discovering Computers, Fundamentals 5 th Ed . Course Technology CENGAGE Learning, Boston, USA. (p. 250 – 251)
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When you start a computer, you will often see a variety of messages being displayed on the screen. These messages do depend on the type of operating system, but are simply system hardware checks.
Here is a new term for you, the kernel which plays a very important part in an operating system. What does the kernel do?
 It’s the core of the operation system.

It manages memory and devices.
 It maintains the computer’s clock.

It starts programs, and
 assigns computer resources: devices, programs, data and information.
It is through the user interface that computer users interact with the computer and vice versa. The user interface is between you the user and the operating system.
There are two types of user interfaces:
 command-line (more difficult to use, requires exact spelling, grammar and punctuation along with specific commands and instructions but it usually prompts for this and has built-in help)
Command-line interface
Command entered by user
Command prompt
 graphical user interface (GUI – most common and you interact with icons, menus and visual images)
Graphical user interface (GUI) – see below
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Unit 2783: Demonstrate knowledge of the components of personal computer systems
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The order in which programs are managed is determined by the operating system.
The order in which tasks are processed is determined by the operating system. Such tasks could be:

receiving data from an input device

processing instructions

sending information to an output device

transferring items from storage to memory and vice versa
With a multi-user operating system, users can have priority over other users. The operating system schedules the tasks to be completed, based on the priority of the user; it’s not always based on a first-come, first-served basis.
Example of managing tasks: How does the operating system handle more than one document being sent to a printer at the same time?
We all know a printer can only print one document at a time. When other documents are sent to the printer, they are placed in a buffer until the printer becomes idle. A buffer is a portion of memory/storage or physical device in which items are placed while waiting to be transferred from an input device or to an output device.
Each device (mouse, keyboard, monitor, printer, scanner etc) that is attached/connected to a computer has its own small program called a driver. This driver tells the operating system how to communicate with the specific device.
Drivers for mouse, keyboard, and monitor generally come preloaded on a computer.
If you want to add a new printer you need to install the printer software (driver) to enable the computer to talk to the printer and thereby print your documents.
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Unit 2783: Demonstrate knowledge of the components of personal computer systems
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Most operating systems provide a means to establish and maintain Internet connections.
Operating systems also provide users with the ability to:
 manage their files (searching, renaming, copying, deleting etc)
 secure a computer from unauthorised access
Write T for True or F for false. Which of the following are operating systems functions?
Managing your files – renaming, copying, deleting, saving.
Creating graphics such as logos and advertisements.
Managing input/output by displaying information on the monitor, sending files to the printer, and responding to the mouse and keyboard.
Reading and writing data to floppy disks.
Creating a financial spreadsheet of accounts.
Fetching, decoding, executing instructions and storing the results.
Formatting a floppy disk
Performing various business analyses and forecasts on financial data.
Keeping track of where your files.
Types of operating systems
There are a number of different operating systems available. Some of them are listed below. They come in three categories:
 stand-alone (complete operating system that runs on a desktop computer, notebook computer or mobile device)
 network (resides on a network server and designed to support a network - not covered in this course)
 embedded (resides in most smart phones and small devices and stored on
ROM)
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