EOC Summary

1. What devices do you use to get data into the computer? An input device enables you to enter data (text, images, and sounds) and instructions (user responses and commands) into the computer. You use keyboards to enter typed data and commands, whereas you use the mouse to enter user responses and commands. Keyboards are distinguished by the layout of the keys as well as the special keys found on the keyboard. The most common keyboard is the QWERTY keyboard. However, over the years, there has been some debate over what is the best layout for keyboards. The Dvorak keyboard is a leader in alternative keyboards. The Dvorak keyboard puts the most commonly used letters in the English language on “home keys,” which are the keys in the middle row of the keyboard. Notebook keyboards are more compact and have fewer keys than standard keyboards. Still, a lot of the notebook keys have alternate functions so that you can get the same capabilities from the limited number of keys as you do from the special keys on standard keyboards. PDAs use the stylus instead of a keyboard. Most computers come with a standard rollerball mouse, but you can also find optical mice, trackball mice, and wireless mice. In a trackball mouse, the rollerball sits on top or on the side of the mouse so that you can move the ball with your fingers. An optical mouse uses an internal sensor or laser to control the mouse’s movement. Wireless mice use batteries and send data to the computer via radio or light waves. Notebooks incorporate the mouse into the keyboard area. Notebook mice include trackball mice, trackpoints, and touchpads. Microphones are the devices used to input sounds, whereas scanners and digital cameras input nondigital text and images.

2. What devices do you use to get data out of the computer? Output devices enable you to send processed data out of your computer. This can take the form of text, pictures, sounds, and video. Monitors display soft copies of text, graphics, and video, while printers create hard copies of text and graphics. There are two basic types of monitors: CRTs and LCDs. If your monitor looks like an old TV set (not the new plasma screen TVs), it has a picture tube device called a CRT (cathode-ray tube). If it is flat, it’s using LCD (liquid crystal display) technology. LCD monitors take up less space and are lighter and more energy efficient than CRT monitors, making them perfect for portable computers. However, CRT monitors are less expensive, have higher resolutions, can be viewed at an angle, and offer better color quality. There are two primary categories of printers: impact and nonimpact. Impact printers have hammer-like keys that strike the paper through an inked ribbon. Nonimpact printers spray ink or use laser beams to transfer marks on the paper. The most common nonimpact printers are inkjet printers and laser printers. Specialty printers are also available. These include multifunction printers, plotters, and thermal printers. When choosing a printer, you should be aware of factors such as speed, resolution, color output, memory, and cost. Speakers are the output devices for sound. Most computers include speakers. However, you may want to upgrade to a more sophisticated speaker system, such as one that includes subwoofers and surround-sound.

3. What’s on the front of your system unit? The system unit is the box that contains the central electronic components of the computer. On the front of the system unit, you’ll find the power source as well as access to the storage devices in your computer. Most PCs include one or two bays for storage devices such as CD drives and DVD drives. Zip drives and floppy disk drives are becoming legacy technologies and are not found on new computers. Most computers include access to USB and other ports on the front panel, and several manufacturers now also include slots on the front of the system unit into which you can insert portable flash memory cards such as Memory Sticks and CompactFlash cards.

4. What’s on the back of your system unit? On the back of the system unit, you’ll find a wide variety of ports that allow you to hook up peripheral devices (such as your monitor and keyboard) to your system. The most common ports found on the back of the system unit are serial ports, parallel ports, USB, and connectivity ports. Traditional serial ports send data one bit (or piece of data) at a time at speeds of 115 Kbps and are used to connect modems to the computer. Parallel ports send data between devices in groups of bits at speeds of 500 Kbps. USB 1.1 and 2.0 ports are fast replacing serial and parallel ports. At 12 Mbps and 480 Mbps, respectively, they transfer data more quickly than their predecessors. Firewire 400 and 800 ports provide even faster data transfer at approximately 400 and 800 Mbps, respectively. Connectivity ports give you access to networks and the Internet and enable your computer to function as a fax machine. Connectivity ports include modem ports and Ethernet ports.

5. What’s inside your system unit? The system unit contains the main electronic components of the computer. The motherboard, the main circuit board of the system, contains the computer’s central processing unit (CPU), which coordinates the functions of all other devices on the computer. RAM, the computer’s volatile memory, is also located on the motherboard. RAM is where all the data and instructions are held while the computer is running. ROM, a permanent type of memory, is responsible for housing instructions to help start up the computer. The hard drive (the permanent storage location) and other storage devices (CD/DVD drives, floppy drives) are also located inside the system unit, as are expansion cards (such as sound, video, modem, and network interface cards) that help the computer perform special functions.

6. How do you set up your computer to avoid strain and injury? Ergonomics refers to how you arrange your computer and equipment to minimize your risk of injury or discomfort. This includes positioning your monitor correctly, buying an adjustable chair that ensures you have good posture while using the computer, assuming a proper position while typing, and making sure the lighting is adequate. Other good practices include taking frequent breaks as well as using other specially designed equipment such as ergonomic keyboards.