Computer Basics

This course will discuss some of the most important basic information you will need to know about computers. There are seven sections:

Types of Computers

There are many different types of computers in today’s marketplace... personal computers to handheld devices. Let’s take a look at some of the different types of computers available today

Personal Computer (or PC)
Small computers designed for an individual user. Their price can range from a few hundred dollars to over a thousand dollars. The personal computer uses "microprocessor technology," which allows everything to be done on one chip in the computer. Personal computers can be used for various tasks and activities, including word processing, spreadsheet development, desktop publishing, database management, and even playing games. Personal computers hit the scene in the seventies. One of the first and most popular personal computers was the Apple II, introduced in 1977 by Apple Computer. Since then, many new models and competing operating systems have appeared on a regular basis. In 1981, IBM entered the scene with its first personal computer, known as the IBC PC, which quickly became the personal computer of choice. Basically, the only company that has survived IBM’s introduction is Apple. Many others have created IBM compatible computers, otherwise known as IBM clones, which cost less and can run the same software.

Mainframe Computers
Computers that can process and store large amounts of information and support many users at the same time. Every major corporation uses mainframes to conduct transactions. Mainframes process and store information entered on terminals. Terminals consist of a keyboard and a monitor and are only used to input and output information. Before the PC, mainframe computers were the only source for computing needs. Today, mainframe computers are still used, but they are not as large (in most cases) as those used before the PC.

Also called laptops, these are portable, battery-operated computers that integrate the display, keyboard, pointing device or trackball, processor, memory and hard drive. They are usually more expensive than a desktop. A special kind of notebook called the Tablet PC allows users to draw and write on a screen for those who prefer handwritten notes over typewritten ones.

Palm Computers
More commonly known as Personal Digital Assistants (PDAs), they are tightly integrated computers that often use a different type of memory for document storage than a PC or laptop. PDAs do not have keyboards but rely on touch screen technology for user input. Additionally, most PDAs are Internet-enabled, which allows a user to access e-mail and the Internet.

Wearable Computers
The latest trend in computing is wearable computers. Essentially, these computers contain common Internet-enabled features as well as software programming, (e.g., e-mail, Internet access, calendar/scheduling, multimedia, database information, etc.) integrated into smart watches, cell phones, visors and even clothing. Examples of a wearable computers are Smart Phones and activity trackers.


Computer Components

There are many different types of components used with computers. Some are listed below:

The computer contains all the major components of a computer system.

An acronym for MOdulator/DEModulator. A modem is a piece of hardware that enables a computer to send and receive data through an ordinary telephone line. There are two main types of modems available in the marketplace today: an Internal Modem and an External Modem. An Internal Modem is a circuit board that plugs into an expansion slot in your computer. This type of modem is usually less expensive than an external modem, but is more difficult to set up. External Modems are small boxes that plug into the back of your computer using a serial port. An external modem may take up room on your desk, but you can use this type of modem with more than one computer. Status lights on the modem tell you about the current transmission. For example, the “RD” light is on when the modem is receiving data. There are three main applications for modems: 1) Connecting to the Internet; 2) Exchanging Information; and 3) Sending and Receiving Faxes.

A television-like screen on which the computer displays information. The size of a monitor is measured diagonally across the screen. Common monitor sizes are 15, 17, 19, 21, and 23 inches. Larger monitors are more expensive and are ideal for desktop publishing and working with graphics or large spreadsheets. There are two types of monitors:

  • LCD Monitor:  LCD is short for “liquid crystal display.” With an LCD monitor, an electric current is passed through liquid causing crystals to align so that light cannot pass through them. In other words, the crystals are like shutters that allow light to pass through or not. With an LCD monitor, you are guaranteed a nice crisp display but they are much more fragile and usually more expensive than CRT monitors.

  • CRT Monitor:  CRT stands for “cathode-ray tubes,” or the type of technology used in a CRT monitor. A CRT monitor works by moving an electron beam back and forth across the back of the screen, which creates an entire screen of images. CRT monitors were the only choice for at-home computer users for many years. Most CRT monitors take up more desk space but cost less than other monitors.

Speakers allow you to hear music and sounds from CDs, the Internet and other programs that require sound.

The main input device for most computers, which is used to type and enter commands. The computer keyboard was modeled after the typewriter keyboard and is designed to input text and characters. Approximately 50 percent of all keyboard keys produce letters, numbers or signs (characters). Other keys can perform actions to facilitate computing needs, such as the windows key, shift key or control key.

There are four categories of keys.

Modifier Keys
The following are considered to be basic modifier keys on the keyboard.

  • Shift Key: This key lets you enter text in uppercase (ABC) and lowercase (abc) letters. Press the Shift Key in combination with another key to type an uppercase letter.

  • Control Key: When you press the Control Key in conjunction with another key, it will perform a special operation. For example, if you press the Control Key in conjunction with the Delete Key, you will be able to delete an entire word.

  • Windows Key: By itself, the Windows Key will open the Start Menu. When pressed in combination with another key, it allows many common functions through the keyboard. For example, if you press the Windows Key and another letter on the keyboard, you may go to the login on your computer (depending upon your computer operating system and program).

  • Alt Key: The Alt Key is used to change the function of another pressed key. For example, simply pressing “F" will type the letter F, but if you hold down either "Alt Key" while pressing "F", the computer will perform an "Alt-F" function, which may be dropping down the file menu on some operating systems.

Lock Keys
There are certain keys on the keyboard that lock part of the keys depending on the selected settings.

  • Scroll Lock: The Scroll Lock was originally designed to modify the behavior of the arrow keys – when the scroll lock was on, the arrow keys would scroll the contents of a text window. Today, only a few modern software programs still allow the scroll lock function to work, such as Microsoft Excel.

  • Numbers Lock:  When depressed, the user can use the numbers on the right of the keyboard as a 10-key pad. Numbers Lock is important to the user when inputting many numbers into a spreadsheet or other database program.

  • Caps Lock:  Just like a typewriter, when this key is depressed, it will capitalize all letters typed.

Navigation Keys
Navigation keys are those keys that allow you to move the cursor around the page.

  • Page Scroll:  These keys are also referred to as the “page up” and “page down” keys, and move the page up and down for easier viewing.

  • Home Key:  The Home Key will place the cursor back to the beginning of the sentence.

  • End Key:  The End Key will place the cursor at the end of the sentence.

  • Arrow Keys:  Buttons on the keyboard that move the cursor in specified directions.

Edit Keys
There are certain edit keys that are on most keyboards.

  • Tab:  This key is used to advance the cursor to the next "tab stop."

  • Insert:  This key is used to overstrike, or in other words, the cursor overwrites while typing. Additionally, it allows the cursor to insert a character at its current position, forcing all characters past it one position further.

  • Backspace:  This key is depressed when a person wants to back up the cursor or delete the information just created.

  • Return/Enter:  This key is depressed when you want to make a hard return or create space.

  • Delete:  When used during normal text editing, depressing this key will discard the character at the cursor’s position, moving all the following characters one position "back" towards the freed place.

Other Keys
There are some other keys on the keyboard that are used, but don’t necessarily fall into a defined category.

  • Print Screen:  Most of today’s keyboards have a print screen key that copies a bitmap image of the current screen to their clipboard (or comparable storage area), and can then be inserted into documents as a screenshot.

  • Escape:  The most common application today of the Escape Key today is to stop whatever the user is doing.

  • Windows Key (PC):  The primary function of this key is to launch the START menu of the computer.

  • Space Bar:  The main purpose of this key is to enter a space in the contents of a document (e.g., space between words in a document).

  • Menu Key (PC):  The primary function of this key is to launch a menu with the keyboard rather than the right mouse button.

  • Number Pad:  The number pad allows a person to type in numbers as they would a 10-key. The number lock must be on to use this feature.

Function Keys
Function Keys are those keys located at the top of your keyboard that read: F1 to F12. Each of these keys is usually programmed by an operating system to allow users to perform certain actions quickly and efficiently. In some instances, F1 is used as a help button, while F12 is used as a way to save a document. Each of these keys has a different function; however, each operating system allows for different actions. Please take a moment to go through the function keys on your keyboard to see what they can do.

About the Mouse and Other Input Devices

There are many different ways you can control what is done on a computer:

A mouse is the most basic tool used to control the information used on a computer. A hand-held device that you move across the desktop to move an arrow (or mouse pointer) across the screen. It is used instead of a keyboard to select and move items (e.g., text or graphics), execute commands, and perform other tasks.

A mouse pad is used to provide a smooth surface for moving a mouse and reduces the amount of dirt that enters the mouse. Hard plastic mouse pads tend to attract less dirt and provide a smoother surface than fabric-covered mouse pads. You can purchase mouse pads with interesting designs or pictures on them at most stores that offer office supplies. Some mouse pads have a built-in wrist support for increased comfort.

A touchpad, or glide point, is a device that is sensitive to pressure and motion. When you move your fingertip across the pad, the pointer on the screen moves in the same direction. This type of pointing device is used often on a laptop.

A touch screen is a touch-sensitive display device. By touching the screen, users can enter a large amount of data. Kiosks and restaurants often use touch screen input devices.

A trackball is an upside down mouse that remains stationary on your desk. You roll the ball with your fingers or palm to move the pointer on the screen. It is a great alternative to a mouse when you have limited desk space. In most cases, you will see the trackball used on a laptop.

A joystick is an input control device that allows you to move people and objects in many computer games. Joysticks are used for arcade-type computer games because they let you move quickly and accurately in any direction.

Users can tap, write and draw to enter data into the computer with a digital pen. The digital pen is a small plastic or metal device called a stylus.

A light pen is a handheld device that detects the presence of light. The pen applies pressure on the monitor to obtain results. Many health care professionals use these types of input devices.


A device that prints a paper copy of documents you create on the computer. Printers are an important part of technology today. In fact, they have come a long way in the past decade. A computer can send data faster than a printer can accept and process the data. A print spooler or print buffer acts as a road block, holding the data and then releasing it at a speed the printer can handle.

  • A print spooler is a program on your computer that stores the information you selected to print. The print spooler stores more information than a print buffer and lets you continue using your computer without having to wait for a document to finish printing. Most operating systems now come with a built-in print spooler.

  • A print buffer is a section of memory within a printer that stores information you selected to print. When the buffer is full, the computer must wait before sending the rest of the data to the printer. The print buffer allows the computer to continue operating even if the printer is still printing.

Different Types of Printers

There are many types of printers available in the marketplace today. We will discuss six of the most common types of printers used for business or personal use.

Dot Matrix
One of the original printers developed for business and personal use. This type of printer strikes pins against an ink ribbon to print closely placed dots in the shape of a character or illustration. They are considered to have lower quality printing and are louder than other printers in the market. They can, however, print multi-page forms (e.g., forms with carbons), which is something most other printers cannot do.

An inkjet printer propels fine droplets of ink toward the surface of the paper. The quality of the printing depends on how many spray nozzles there are and how many ink cartridges it uses. Inkjet printers are a low-cost way to create high quality color documents. They are the most common type of home printer today.

This is a common printer that produces high quality documents on plain paper. Laser printers use a xerographic printing process to create documents; however, unlike a copier, the image is created by a laser directly scanning the information to the paper. A laser printer has a higher resolution, a lower cost per page and faster print speed than either an inkjet or dot matrix printer.

This type produces photo lab quality prints. Some just print photos on a 3 x 5 or 4 x 6 inch cards. Others print legal size, letter size and sometimes even larger. The larger the prints, the higher the cost of the printer. Usually, these printers run up to a few hundred dollars and are ideal for small business and home use.

Thermal Wax
These printers are used mostly for presentation transparencies and color proofing documents prior to printing at an offset printing press. They use sheet-sized, belt driven ribbons to produce documents. The print head contains heating elements that melt colored wax onto paper as it is rolled through the printer. Additionally, you must use very smooth or specially-coated paper for best results.

Dye Sublimation
This type of printer is used most often in the design and publishing industry as well as the scientific research industry where attention to detail is necessary. The dye sublimation printer is similar to the thermal wax printer, except that it uses plastic dye film instead of colored wax.

Printer Speed and Resolution

The speed of a printer determines how quickly it can print the pages you select. Printer speed is measured in pages per minute (ppm) or characters per second (cps). A higher speed results in faster output.

The resolution of a printer determines the quality of the images it can produce. A higher resolution results in a sharper, more detailed image. Printer resolution is measured in dots per inch (dpi).


Inside the Computer

So how does a computer work? Let’s go through a few basic components inside a computer.

The main circuit board of a computer. All electrical components plug into the motherboard.

Central Processing Unit (CPU)
This chip is the computer's brain; it does all the calculations for the computer.

Random Access Memory (RAM), or RAM
Temporarily stores information inside a computer; this information is lost when you turn off the computer.

Hard Drive
The primary storage device that a computer uses to store information. There are internal and external drives available.

Power Supply
Regulates the amount of electricity that a computer needs to use.

Floppy Drive
Stores and retrieves information on floppy disks. Today a floppy drive typically has about 1.4 Megabytes of memory capacity.

A CD-ROM drive reads information stored on compact disks (CDs).

Expansion Cards
They are located on the motherboard and they allow you to add devices to the system unit, such as an internal modem, sound card, video card, or other enhancements. A computer comes with one or more expansion slots that may connect the following:

  • Video: A video card generates the images displayed on the monitor.
  • Sound: A sound card lets your computer play and record sound.
  • Modem: A modem card lets your computer exchange information through telephone lines.
  • Network: A network interface card allows you to connect to computers and share information and equipment.
  • USB: The USB card allows you to connect USB enabled devices, such as cameras, optical drives, etc., to your computer. You can also use the USB port to network to other computers.
  • Firewire: The firewire card allows you to connect firewire enabled devices, such as videos, camera, etc., to your computer.)


Back of the Computer

Let’s say that you are trying to work at your computer and you have an issue. You call your Internet Service Provider (ISP) or other Help Desk and they are trying to help you with your issue. The operator asks you to plug something into your USB Port. Where is that?

We will now take a look at the parts of the computer that are located on the back of the computer base.

  1. Case Fan - This is the cooling fan for the computer case, which helps to keep your computer cool. A hot computer is a dead computer, so it is critical that the fan functions appropriately.

  2. Firewire Port – A high-speed port that connects the computer to electronic devices like video cameras, drives etc.

  3. Keyboard/Mouse Port (PS/2) - This is where you plug in your keyboard and/or mouse.

  4. USB Port – Universal Serial Bus (USB) is a type of port that allows you to connect over a hundred devices using only one port, such as printers, keyboards, scanners, and external drives. In some of the newer PCs, this port can be found on the front of the computer.

  5. Network (Ethernet) Port – This port allows you to connect the computer to a network.

  6. Graphics Card - This is where you will plug in your monitor.

  7. Air Vent - This vent lets air flow into your computer case, helping to keep your computer cool.

  8. Sound Card - This sound card will let you plug in your microphone and speakers.  There are also line-in and line-out jacks, which are used to import or export sounds.

  9. Power Plug - This is where you will plug in your power cord.

  10. Power Supply Fan - This is the cooling fan for the power supply on your computer.


Computer Memory

Memory is one of the most essential parts of a computer, because it is constantly being used. It allows the computer to access and store data and instructions fast and temporarily. While memory is a type of electronic storage, the two terms memory and disk storage are often mistakenly interchanged.

Memory is a form of temporary storage and comes in the form of chips. Since memory allows fast and temporary access to data and instructions, it is also considered to be the primary storage on the computer. Information is stored permanently on disk storage and the hard drive, or secondary storage.

Computer Memory is Unstable

A distinguishing characteristic of memory is its instability. Because memory is temporary storage, it requires power in order to maintain the information. Once the power is turned off, any data or instructions stored in memory are lost. A computer uses several different forms of memory.

Random Access Memory, or RAM, is the main form of memory that a computer uses, and can access any information stored in random locations. RAM is critical and considered to be the most important factor to the performance of your computer. The more RAM your computer has, the smoother it runs and the more programs it can run at one time. Additional RAM can be added to your computer; however, you will want to check how much RAM you already have. Installing additional RAM may be necessary if you continually go beyond normal usage and are using more professional and audiovisual applications that require higher speed and performance.

Read-Only Memory, or ROM, is another type of memory that only reads information and does not write it; therefore, the contents cannot be changed in ROM as they can be in RAM. In addition, ROM keeps its contents when the power is turned off. It does not need a constant supply of electricity, as does RAM. ROM is important because it holds the instructions for starting up your computer.

Internal Cache Memory
Internal Cache memory is the first place a computer looks when it needs data. It is located on the CPU chip and also referred to as the primary cache. If the computer cannot find the data it needs in the internal cache, the computer looks in the external cache.

External Cashe Memory
External cache memory is on the motherboard and consists of Static RAM (SRAM) chips. External cache is slower than internal cache, but is much faster than RAM. External cache is also called L2 or secondary cache. Using cache memory is similar to working with documents in your office. When you need information, you look for information in a specific order.

Each step along the way takes up more of your valuable time. First, you would look through documents on your desk (or your internal cache). Then, if not found, you would look through documents in your desk drawer (or your external cache). Finally, if not found, you would then look through documents in your filing cabinet (or RAM). To give you some perspective, working without cache memory would be similar to looking through the filing cabinet each time you need a document.

Virtual Memory
Virtual Memory serves an important role in your computer; it frees up space in memory by transferring data from RAM that has not been used recently to the hard disk. Virtual memory copies the information onto the hard disk, and when it is needed again, it can be copied back to memory. Essentially, virtual memory swaps the memory back and forth and creates the illusion of more space.

Basic Input/Output System, or BIOS, is part of a computer’s operating system, usually a part of the motherboard. One of the most important functions of the BIOS is to load the operating system. It performs the power-on self-test and is responsible for interfacing hardware devices with the operating system. Information on the BIOS is critical for the computer to function; therefore, it is stored on a ROM chip separate from the hard drive to protect it from anything happening to it.

Flash Memory
Like ROM, Flash Memory is non-volatile, meaning it retains its information even when the power on your computer is off. This is very important, considering one of the common uses of flash memory is for the BIOS of the computer. In addition to the BIOS chip, flash memory also comes in the form of removable cards. Although a hard disk is also non-volatile, some people prefer to use flash memory cards because they are smaller, lighter, and are accessed faster. The following are examples of flash memory: Compact Flash (most often found in digital cameras), Smart Media (most often found in digital cameras), Memory Stick (most often found in digital cameras), PCMCIA Type I and II memory cards (used as solid-state disks in laptops), and memory cards for video game consoles.


Computer Storage

Secondary storage, or auxiliary storage, is that which is currently not being processed, but is filed away until it is ready to be accessed when needed. Additionally, it is nonvolatile, meaning it will not lose information when the computer’s power is turned off.

Secondary storage is usually formatted according to a file system, which provides the user with the ability to access information easily, and tracks usage and capabilities as well. In the computer systems of today, much more information is stored for longer periods of time in secondary storage. In most of today’s computers, hard disks are used as secondary storage. The following list other means of secondary storage.

Magnetic disks
The type of secondary storage most often used involves some sort of magnetic disk, which uses magnetism to store data on a magnetic surface. This type of storage is reliable, gives direct access to data, and has a high storage capacity. Usually, a drive spins the disk underneath a read/write head, where it reads data from a disk and writes data to a disk. The most popular type of magnetic disk is the hard disk. It is usually installed inside the computer, though you can find some that are removable or used as a cartridge. The hard drive is what controls the motion of the hard disk, although these two terms are usually used interchangeably. Protecting your hard drive is a critical part of computer maintenance. If you do not protect it, you will lose a lot of data, which can sometimes lead to loss of money in your business. Let’s take a look at some important ways to do this:

  1. If you receive files on a floppy disk from a colleague or friend, make sure you check for viruses before using the files.

  2. Create and then strictly follow a back-up schedule; most people back up their hard drive once a day or once a week. Hard drive disasters always seem to happen right after you miss a scheduled back-up.

  3. You should regularly use an anti-virus program to check for viruses on your computer. A virus disrupts the normal operation of a computer and can cause a variety of problems.

  4. Check for viruses before using any files you receive through a modem.

  5. You should copy the files stored on your hard drive to floppy disks or an optical storage device; this provides extra copies in case the original files are stolen or damaged due to viruses or computer failure.

  6. Be sure to implement a spyware remover program on your computer. Spyware is a program placed on a computer without the user’s knowledge that secretly collects information about the user, often related to web browsing habits. A spyware remover is a program that detects and deletes spyware.

  7. Be sure to implement filter programs that block or remove certain items from being displayed, such as anti-spam programs, web filters, and pop-up blockers.

Floppy disks
Although the “floppy” disk is not as commonly used today as it has been in the past, it is important to discuss. There are two main sizes of floppy disks: 5-1/4” (rarely, if ever, used now) and 3-1/2” (beginning to quickly leave the market). Both of these floppy disks are made of Mylar, with an oxide coating, which provides the magnetic quality for the disk. The key to these disks is what is inside the cover of the disk, not the outside. It is important to note that some of today’s computers do not even come with a floppy drive available for use.

Jaz and Zip drives
Popular removable hard drives include Jaz and Zip drives. A jaz drive can store up to two GB (2,000 MB) of data, whereas a zip drive can store up to 750 MB of data.

Flash memory (e.g., USB sticks or keys)
Like ROM, Flash Memory is non-volatile, meaning it retains its information even when the power on your computer is off. This is very important, considering one of the common uses of flash memory is for the BIOS of the computer. In addition to the BIOS chip, flash memory also comes in the form of removable cards. Although a hard disk is also non-volatile, some people prefer to use flash memory cards because they are smaller, lighter, and are accessed faster. The following are examples of flash memory: Compact Flash (most often found in digital cameras), Smart Media (most often found in digital cameras), Memory Stick (most often found in digital cameras), PCMCIA Type I and II memory cards (used as solid-state disks in laptops), and memory cards for video game consoles.

CD-ROMsCD-ROMs (Compact Disk-Read Only Memory) are used primarily for audio recording and data storage. They are “read-only” storage devices as the data layer is near the top of the disk.

DVDs (or Digital Video Device or Digital Versatile Device) are optical disks primarily used to record movies.

USB Drives
The USB Drive is a new type of flash memory storage device that is called one of the following names: flash drive, flash pen, thumb drive, key drive, or mini-USB drive. All types of USB Drives are small and plug into a USB port on your computer. You can store up to 1 GB or more with this type of storage device.

External Hard Drives
External Hard Drives come in many shapes and forms, and are becoming more and more popular on the market today. These storage devices simply plug into a USB port and you can download your entire computer onto them. Some individuals use it as a means of back-up storage, while others use it to bring their “work computer” to their “home computer.”


Operating Systems

In today’s environment, all desktop computers have an operating system (OS). The most common OS for personal computers (PC), such as Dell or HP, is developed by Microsoft®, called Windows™ XP or Vista. The most common OS for Macintosh computers is developed by Apple® and the UNIX family of operating systems. Furthermore, many corporations use UNIX® or Linux for their servers, since they are handling multiple groups and computers.

Purpose of Operating Systems

Each operating system is specific to the needs of that particular type of computer system. The Operating System (OS) is the backbone of the computer, managing its software and hardware. It is the first thing loaded onto the computer; without it, the computer is useless. The following are the two main purposes of any OS:

  • Manage the hardware and software of the computer, such as the CPU, memory, disk space, etc.

  • Provide a way for all applications to deal with the hardware of the computer without having to know the details of the hardware.


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