Basic parts and functionality of the computer
Whether it is a telephone with a touch screen, a laptop, a tablet or a desktop, all computers consist of certain basic elements. This basic assembly is formed usually of a motherboard, a processor, central memory, hard disc drive, connections, the monitor as well as the keyboard, mouse or some kind of a touch pad. The majority of the listed parts are inside the cabinet, but knowing them is important in order to manage different problem situations.
The computer case
The computer case contains the most important components of the computer: the motherboard, the processor, random access memory modules, the hard drive etc. It may not be possible to exchange the components in a laptop computer, but in a desktop computer you have much more influence on the parts inside the cases.
The motherboard
The motherboard is the part of the computer where such things as the processor, memory modules, expansion cards and external devices are attached. This means that the motherboard controls the functions of different components. The number of connection slots for peripheral devices and the number and type of memory slots are important properties of the motherboard. In addition to the various connections, the motherboard also has a small battery ensuring that settings made on the board are retained even when the computer is switched off.
The processor
The processor can be considered to be the ‘engine’ of the computer because it executes the lion’s share of the information processing; the processor fetches commands and necessary information from the RAM, carries out the tasks specified by the commands, and returns the processed information to the RAM. The speed of a computer depends largely on the speed of the processor. The processor’s speed, in turn, is affected by various factors, such as the so-called clock frequency (usually expressed as gigahertz, GHz), the number of cores and of the so-called cache memory inside the processor.
Random access memory
The RAM (Random Access Memory) is a memory storage that functions during computer use and is especially utilized by the processor. In modern computers, the amount of RAM is around 4 – 16 GB depending on the type and purpose of the computer (please see data measurement units for more information). The RAM consists of one or more memory modules (see image above). When the computer is started, the operating system is loaded into the RAM (an operating system is a program that controls the devices and programs in a computer – please see operating systems for more information). The computer also loads the files being processed – music, assignments, videos etc. – to the RAM. If there is enough RAM, the computer executes requested tasks quickly. This is why it is a good idea to add to the memory by buying more memory modules as the need arises.
Hard drive
The hard drive is the permanent memory of the computer where saved files remain even when the computer is turned off. This is why the hard drive is used for saving files. The capacity of hard drives varies; currently the typical capacity is 500-1000 GB, but hard drives of over 1500 GB, i.e. 1,5 terabits, are also available. However, the capacity of the internal hard drives in laptop computers is often less than that. You can add to the capacity of your computer by attaching an additional hard drive, either internally or externally. More information about storage sizes can be found here.
The hard disk is used for the storage of the computer’s operating system and all important files. It is therefore packed in a fixed protective housing. The disks may become damaged in spite of this protection, so you should absolutely make backup copies of files on the hard drive from time to time (please see backup copies for more information)!
DVD and Blu-ray drives with writing capabilities
Most computers these days come with a Blu-ray drive or a DVD (Digital Versatile Disk) drive with writing capabilities, with which you can burn such things as backup copies of important files to DVDs. CD drives are older and have mostly been replaced with DVD drives. CD drives can only burn data on CDs, which have a substantially smaller storage capacity, while DVD drives can burn data to both CDs and DVDs with more capacity (please see recording media for more information).
The display and display adapter
Most computer displays are so-called LCD displays (Liquid Crystal Display), where the image display is produced by liquid crystals between two transparent sheets. Display sizes range between only a few inches in handheld apparatuses to large 24 inch desktop displays. One of the most important features of the display is its resolution, i.e. how many pixels (picture elements) the image consists of. A normal 22 to 24-inch widescreen display usually has 1920 pixels horizontally and 1200 pixels vertically (1920×1200). These displays can reproduce Full HD (full high definition) image. No matter what the type of display is, the computer must contain a so-called display adapter that allows you to attach the display to the computer and controls the display image. Practically all motherboards come equipped with a display adapter, so you do not need to buy one separately, unless you want to enhance the capabilities of your desktop computer e.g. for gaming, video editing, or 3D imaging purposes.
Keyboard
A standard keyboard has 102 keys. The keys are divided into alphabetical (a-z), numerical (1-0) and special (Function, Ctrl, Alt etc keys). In addition to the usual alphabetical and numerical keys, you should know at least the following special keys that are located among the alphabetical ones. Below are shown some typical keys on a PC keyboard. The keyboard mapping on Mac computers is almost identical to PC keyboards, but the special keys Ctrl and Alt work slightly differently. In addition, the Mac keyboard has Fn and Cmd keys instead of the Windows key.
   | Ctrl: (Control) is used in combination with other keys for different actions. The combination Ctrl+C, for example, copies the chosen data to the memory. Alt: (Alternative) is used like the Ctrl key. Sometimes both these keys are used in combination: Ctrl+Alt+Del, for example, brings up the task manager(in Windows XP). Alt Gr: (Alternative Graphics) produces the ‘third character’ of the keys, e.g. @, $, £ and }. With this key, you can also create the ~ character (important for the internet). Create the ~ character as follows: press ALT-GR and the ~ key at the same time, and finish with the space bar. You can make so-called ascii characters with combinations of the Alt key and numerals, e.g. Alt+0176 makes the character for temperature °. You can choose to either add special characters in this way or through an application. Most text processing programs have their own menu for special characters. |
 | Shift: capitalizes letters and the special characters on the numerical keys, among others. |
 | Caps Lock: locks the capitalization of letters. This function is connected with an A or Caps lock pilot light on the keyboard. It turns on the light when the function is in use. |
 | Tab: the tabulator is mainly used in word processing: each time you press the tab button, the cursor moves to the next tab stop on the same row. The key can also be used for alternating between window displays. |
 | Backspace: removes the characters to the left of the cursor, i.e. what you just wrote. This key can also be used to remove a larger portion of text. |
 | Enter: by pressing this key you can change paragraphs or e.g. accept a function. |
There are more special keys above the alphabetical keys; of these the function keys (please see next image) are used for different functions, depending on situation and the program currently being used. The manual for these functions is usually available in the manual for the program.
To the left and right of the function keys, you will find the following additional keys:
 | Esc (Escape): mostly used to cancel a function, or e.g. to close a menu window. |
 | Home and End: these keys bring the cursor to the top or the bottom of the line. Page Up and Page Down: move the page up or down. Insert: starts the insert function, where the text you are writing replaces the text to the right of the cursor. Delete: deletes the character to the right of the cursor. |
 | Arrow keys: move the cursor in the direction shown by the arrows. |
 | The number pad is activated with the Num Lock key: when it is activated, the pilot light with the symbol 1 or the text Num Lock lights up. Usually the Num Lock function has been set to be turned on when starting up the computer. If the pilot light is not turned on, the keys function in the way indicated by the symbols on the keys (8 up, 4 left, 6 right, 2 down). |
The keyboard also has the rarely used keys Print Screen, Scroll Lock and Pause. The Print Screen key lets you take a picture of the display (Alt+PrintScreen takes a picture of the currently activated window) and send it to your clipboard, Scroll Lock locks the scrolling of the display and the Pause key can be used e.g. for stopping the loading of the system during start-up.
For more information on hotkeys and key combinations, see the additional reading material.
Pointing devices
Traditionally, most programs have been designed to be used with a mouse. The mouse cursor seen on the screen of the computer moves along with the mouse. The cursor can be used to select menu commands and areas, as well as activating different objects by clicking the mouse keys.
Mouse
You can attach a traditional mouse with or without a cord to any computer. Cordless mice use radio waves to relay movement from the mouse to the computer (for this mouse, a small radio receiver is attached to the computer).
Touchpad
Almost all laptop computers have a touchpad which is used to move the cursor. Some models also have a so-called pointing stick. In addition, portable computers have keys with the clicking function of mouses. The touchpad is a pad where you can control the cursor by moving your finger along the pad. Tapping the pad serves the same function as clicking a mouse.
Pointing stick
The pointing stick is a ‘nub’ located in the middle of the keyboard, and controls the cursor. The pointing stick can be ‘clicked’ by tapping the stick or using the separate buttons in the keyboard. In the right-hand image above, you can see a portable computer with both a pointing stick (blue) and a touchpad (the large, dark grey area in front of the keyboard).
Touchscreen
Devices that are smaller than a laptop, such as phones and tablets, usually do not have a separate keyboard or pointer device. In these devices, the entire screen of the device works as an input device. A touchscreen is used like the track pad on a laptop, and when typing is required, a keyboard appears on the screen.
