hardware+in+the+classroom


 * What is Hardware?**

Your PC (Personal Computer) is a system, consisting of many components. Some of those components, like Windows XP, and all your other programs, are software. The stuff you can actually see and touch, and would likely break if you threw it out a fifth-story window, is hardware.

Not everybody has exactly the same hardware. But those of you who have a desktop system, like the example shown in Figure 1, probably have most of the components shown in that same figure. Those of you with notebook computers probably have most of the same components. Only in your case the components are all integrated into a single book-sized portable unit.


 * Examples of Hardware**
 * RAM
 * The Hard disk
 * The Mouse
 * The Keyboard
 * Printer
 * Scanner
 * Beamer
 * Speaker
 * Monitor

There's too much "stuff" on your computer's hard disk to use it all at the same time. During the average session sitting at the computer, you'll probably use only a small amount of all that's available. The stuff you're working with at any given moment is stored in random access memory (often abbreviated RAM, and often called simply "memory"). The advantage using RAM to store whatever you're working on at the moment is that RAM is very fast. Much faster than any disk. For you, "fast" translates to less time waiting and more time being productive.
 * Random Access Memory (RAM)**

So if RAM is so fast, why not put everything in it? Why have a hard disk at all? The answer to that lies in the fact that RAM is volatile. As soon as the computer is shut off, whether intentionally or by an accidental power outage, every thing in RAM disappears, just as quickly as a light bulb goes out when the plug is pulled. So you don't want to rely on RAM to hold everything. A disk, on the other hand, holds its information whether the power is on or off.

The Hard Disk
All of the information that's "in your computer", so to speak, is stored on your computer's //hard disk.// You never see that actual hard disk because it's sealed inside a special housing and needs to stay that way. Unlike RAM, which is volatile, the hard disk can hold information forever -- with or without electricity. Most modern hard disks have tens of billions of //bytes// of storage space on them. Which, in English, means that you can create, save, and download files for months or years without using up all the storage space it provides. In the unlikely event that you do manage to fill up your hard disk, Windows will start showing a little message on the screen that reads "You are running low on disk space" well in advance of any problems. In fact, if that message appears, it won't until you're down to about 800 MB of free space. And 800 MB of empty space is equal to about 600 blank floppy disks. That's still plenty of room.

Obviously you know how to use your mouse, since you must have used it to get here. But let's take a look at the facts and buzzwords anyway. Your mouse probably has at least two buttons on it. The button on the left is called the //primary mouse button//, the button on the right is called the //secondary mouse button// or just the //right mouse button//. I'll just refer to them as the left and right mouse buttons. Many mice have a small wheel between the two mouse buttons, as illustrated in Figure 3. Figure 3

The idea is to rest your hand comfortably on the mouse, with your index finger touching (but not pressing on) the left mouse button. Then, as you move the mouse, the //mouse pointer// (the little arrow on the screen) moves in the same direction. When moving the mouse, try to keep the buttons aimed toward the monitor -- don't "twist" the mouse as that just makes it all the harder to control the position of the mouse pointer. If you find yourself reaching too far to get the mouse pointer where you want it to be on the screen, just pick up the mouse, move it to where it's comfortable to hold it, and place it back down on the mousepad or desk. The buzzwords that describe how you use the mouse are as follows:
 * Point : To point to an item means to move the mouse pointer so that it's touching the item.
 * Click : Point to the item, then tap (press and release) the left mouse button.
 * Double-click : Point to the item, and tap the left mouse button twice in rapid succession - click-click as fast as you can.
 * Right-click : Point to the item, then tap the mouse button on the right.
 * Drag : Point to an item, then hold down the left mouse button as you move the mouse. To //drop// the item, release the left mouse button.
 * Right-drag : Point to an item, then hold down the right mouse button as you move the mouse. To //drop// the item, release the right mouse button.

The Keyboard
Like the mouse, the keyboard is a means of interacting with your computer. You really only need to use the keyboard when you're typing text. Most of the keys on the keyboard are laid out like the keys on a typewriter. But there are some special keys like Esc (Escape), Ctrl (Control), and Alt (Alternate). There are also some keys across the top of the keyboard labeled F1, F2, F3, and so forth. Those are called the //function keys//, and the exact role they play depends on which program you happen to be using at the moment. Most keyboards also have a //numeric keypad// with the keys laid out like the keys on a typical adding machine. If you're accustomed to using an adding machine, you might want to use the numeric keypad, rather than the numbers across the top of the keyboard, to type numbers. It doesn't really matter which keys you use. The numeric keypad is just there as a convenience to people who are accustomed to adding machines. Figure 4 Most keyboards also contain a set of //navigation keys//. You can use the navigation keys to move around around through text on the screen. The navigation keys won't move the mouse pointer. Only the mouse moves the mouse pointer. On smaller keyboards where space is limited, such as on a notebook computer, the navigation keys and numeric keypad might be one in the same. There will be a Num Lock key on the keypad. When the Num Lock key is "on", the numeric keypad keys type numbers. When the Num Lock key is "off", the navigation keys come into play. The Num Lock key acts as a toggle. Which is to say, when you tap it, it switches to the opposite state. For example, if Num Lock is on, tapping that key turns it off. If Num Lock is off, tapping that key turns Num Lock on.

Combination Keystrokes (Shortcut keys)
Those mysterious Ctrl and Alt keys are often used in combination with other keys to perform some task. We often refer to these combination keystrokes as shortcut keys, because they provide an alternative to using the mouse to select menu options in programs. Shortcut keys are always expressed as: //key1//+//key2// where the idea is to hold down //key1//, tap //key2//, then release //key1//. For example, to press Ctrl+Esc hold down the Ctrl key (usually with your pinkie), tap the Esc key, then release the Ctrl key. To press Alt+F you hold down the Alt key, tap the letter F, then release the Alt key.

A printer is a device that prints text or illustrations on paper. There are many different types of printers. In terms of the technology utilized, printers fall into the following categories:
 * Printer**
 * **daisy-wheel:** this type of printer is similar to a ball-head typewriter, this type of printer has a plastic or metal wheel on which the shape of each character stands out in relief. A hammer presses the wheel against a ribbon, which in turn makes an ink stain in the shape of the character on the paper.Daisy-wheel printers produce letter-quality print but cannot print graphics.
 * **dot-matrix:** Creates characters by striking pins against an ink ribbon. Each pin makes a dot, and combinations of dots form characters and illustrations.
 * **ink-jet:** Sprays ink at a sheet of paper. Ink-jet printers produce high-quality text and graphics.
 * **laser:** Uses the same technology as copy machines. Laser printers produce very high quality text and graphics.
 * **LCD & LED:** Similar to a laser printer, but uses liquid crystals or light-emitting diodes rather than a laser to produce an image on the drum.
 * **line printer:** Contains a chain of characters or pins that print an entire line at one time. Line printers are very fast, but produce low-quality print.
 * **thermal printer:** An inexpensive printer that works by pushing heated pins against heat-sensitive paper. Thermal printers are widely used in calculators and fax machines.

Printers are also classified by the following characteristics: Some printers, notably dot-matrix printers, are limited to one or a few fonts. In contrast, laser and ink-jet printers are capable of printing an almost unlimited variety of fonts. Daisy-wheel printers can also print different fonts, but you need to change the daisy wheel, making it difficult to mix fonts in the same document.
 * quality of type:** The output produced by printers is said to be either letter quality (as good as a typewriter), near letter quality and draft quality. Only daisy-wheel, ink-jet, and laser printers produce letter-quality type. Some dot-matrix printers claim letter-quality print, but if you look closely, you can see the difference.
 * speed:** Measured in characters per second (cps) or pages per minute (ppm), the speed of printers varies widely. Daisy-wheel printers tend to be the slowest, printing about 30 cps. Line printers are fastest (up to 3,000 lines per minute). Dot-matrix printers can print up to 500 cps, and laser printers range from about 4 to 20 text pages per minute.
 * impact or non-impact:** Impact printers include all printers that work by striking an ink ribbon. Daisy-wheel, dot-matrix, and line printers are impact printers. Non-impact printers include laser printers and ink-jet printers. The important difference between impact and non-impact printers is that impact printers are much noisier.
 * graphics:** Some printers (daisy-wheel and line printers) can print only text. Other printers can print both text and graphics.