Unit 1 : Computers

Anatomy of a computer

What makes a computer a computer? Or, what is a computer? A computer is an electronic device, operating under the control of instructions stored in its own memory, that can accept input (data), process the data according to specified rules (process), produce results (output), and store the results for future use (Shelly, Freund and Vermaat, 2010). Therefore one could say a computer is a programmable machine, whose three principal characteristics are: It responds to a specific set of instructions in a well-defined manner and it can execute a pre-recorded list of instructions (known as programs) and gives feedback (output).
Nowadays there are 3 main categories of computers which fit the bill of personal computers. These are:

1. The desktop computer. This is the one generally referred to as the PC,
2. Laptop,
3. Mobile devices. In this category you will find smartphones, tablets, Personal Digital assistants (PDAs).

Whatever the make or category all general-purpose computers require the following hardware components:

1. Memory: enables a computer to store, at least temporarily, data and programs,
2. Mass storage device: allows a computer to permanently retain large amounts of data. Common mass storage devices include solid state drives (SSDs) or disk drives and tape drives,
3. Input device: usually a keyboard and mouse, the input device is the conduit through which data and instructions enter a computer. In the case of touch screens or smartphones the keyboard may be a software component.
4. Output device: a display screen, printer, projector, or other device that lets you see what the computer has accomplished,
   Central processing unit (CPU): the heart of the computer, this is the component that actually executes instructions.

We shall now look at each of these components individually:

The Monitor

The monitor looks like a television screen and is where you see what is happening on your computer. By using shadows and graphics with over a million different colors, much of what you see will appear 3-dimensional. Think of this as the ‘face’ of the computer.

The CPU (Central Processing Unit)

The CPU houses the machinery that allows your computer to work. Think of this as the ‘brains’ of the computer. This component looks very different in desktops and laptops, but it works the same.

The keyboard

The keyboard is one of two ways to interact with your computer. The keys should mostly mimic a traditional typewriter.

The mouse

This is the other way to interact with your computer. Most mice have two buttons, a right and a left button, and a scrolling wheel in the middle.
To turn a computer on, simply press the power button once (no need to hold the button, just press and release). The location of the power button differs with each brand but it is usually marked with the symbol for power.

Once you turn the computer on, the computer will go through a series of automated tasks before it is ready for you to interact with it; this process is called “start-up.” This process will last between one and two minutes. If the computer is not working correctly, you may see an error message during start-up. If the computer is performing as it should, however, you will probably see one of the following screens:

You will then see a “Log On” window, and it means that the computer is password protected. If you do not see this window upon starting the computer, you can assume that your computer is not password-protected and may be used by anyone. To log on, you simply enter your username and password. If you are using the library’s computers, this could be your library student number.

To shut down the computer click on the start button and choose the option you want. The options include:

1. Shutdown: This button/choice totally shuts down the computer. It closes all open tasks or programs and switches off the computer.
2. Log off: Similar to shut down in that it closes all programs, but does not shutdown the computer. Instead it locks the computer so that someone else can log in.
3. Switch user: This option allows someone else to log in whilst your account is still logged in. This can help you if you want to temporarily give access to someone whilst you are still working on the computer.
4. Hibernate: This option saves your work and shuts down your computer. When you restart the computer you can resume where you left off.
5. Sleep: This option is similar to Hibernate but the computer does not shut down. The computer is in a power saving mode./li>
6. Lock: This is for locking the computer to prevent use by unauthorised users.
7. Restart: The computer shuts down and immediately starts again.

Now let’s move to the desktop.