Untitled

What is a Computer?

First before you need to know how a computer works you need to know what a computer is. It's easy to point at the box sitting on your desk and say "this is a computer." But what do we mean by computer? A computer is an appliance just like anything else. Your toaster is a food appliance whereas your computer is an information appliance. You put bread into a toaster, and you get toast. With a computer, information is put in, and information comes out.

A Personal Computer (PC) is a general-purpose tool built around a microprocessor. It has lots of different parts -- memory, a hard disk, a modem, etc. -- that work together. "General purpose" means that you can do many different things with a PC. You can use it to type documents, send e-mail, browse the Web, play games, etc.

How Computers Work

The topics to be covered are as follows: Input devices, Output devices, Input/Output devices, Storage devices, Processors, and Operatins Systems. This is a pretty complete list of the principle computer components.

Input Devices

Input devices are the first part of the computer that I am going to be discussing. An input device is a device that puts data into the computer. A good example is the Mouse or Keyboard. An input device allows the user to command the computer. So this means the keyboard takes commands from you and then electronically passes the data to the computer. There are a number of ways in which the user can pass commands and information to the computer-keyboards, mice, and joysticks are some of the most common input devices but there are others. Using any one of these is actually pretty simple, but that's only because there is a lot of work going on inside the PC to make it easy.

Graphical User Interface (GUI) pointing device is usually called a mouse, and is the first input device that I am going to define. The mouse was invented by Douglas Engelbart of Stanford Research Center in 1963, and pioneered by Xerox in the 1970s; the mouse is one of the great breakthroughs in computer technology because it frees the user to a large extent from using the keyboard. The mouse did not become very widely used until the 1980's. There are four basic types of mice. The mechanical mouse, the optomechanical mouse, the optical mouse, and the glidepoint touch pad.

The mechanical mouse has a rubber ball that rolls on different surfaces. When the ball rolls it has sensors that detect the movement and send that information back to the computer and the computer moves the screen pointer accordingly.

The only difference in the optomechanical mouse and the mechanical mouse are it uses optical sensors to detect the movement of the ball.

The optical mouse is a different type of mouse, because it uses a laser to detect movement over a surface. You don't have to worry about a mechanical ball getting dirty, and it rolls on about any surface. Another plus is that it responds more quickly, and precisely than the mechanical or optomechanical mouse.

Glidepoint is my favorite type of mouse. The mouse is a flat pad, and can be held in the palm of your hand while you use one of your fingers to glide across the surface of the pad. To click a button you can tap the pad lightly or you can use the button on the mouse.

A keyboard is defined as the set of typewriter-like keys that enables you to enter data into a computer. I will mention two types of keyboards, the first is the QWERTY and the other is the DVORAK. You may wonder why these have such weird names right? Well their name comes from the first six letters at the top left of the keyboard. Most people including me have the QWERTY style. The keyboard has been around for a long time and, the first one was made way back in the 1800's for mechanical typewriters. The QWERTY was made after the DVORAK to slow typists down because they were typing so fast they were jamming the keys on the typewriters. The DVORAK design has the letters positioned for speed typing. The keyboard has many uses, and just to name a few: Cash Registers, Computers, Typewriters&ldots;and so on.

Microphones are another kind of input device. Microphones just convert a real sound wave into an electrical audio signal. In order to do so, they have a small, light material in them called the diaphragm. When the sound vibrations through the air reach the diaphragm, they cause the diaphragm to vibrate. This in turns will somehow cause an electrical current in the microphone to vary, whereupon it is sent out to a mixer, preamplifier or amplifier for use. Microphones are typically classified according to how the diaphragms produce sound.

Output Devices

The output devices in a computer allow computer systems to communicate with the users or other computer systems. The output devices do exactly the opposite as the input devices. They translate the data in the computer from digital signals to output that can be discerned by users or other computers. Outputs can exist in electronic form (as on a monitor), in hard copy (as on paper) or in magnetic media (as in network communications). The form of the output often depends on the type of data being processed by the computer, and can be used to provide feedback of a user actions or a final results of a process. The output devices that will be mentioned in this section include; printers, monitors, and speakers.

The speaker is the first output device to discuss. The speaker is a device for converting electrical energy into acoustical signal energy that is radiated into a room or open air. This device consists essentially of a thin flexible sheet called a diaphragm that is made to vibrate by an electrical signal from an amplifier. The vibrations create sound waves in the air around the speaker that radiate into the room.

A monitor, which is another output device, is one of the parts of the computer that displays information that your computer sends it. Monitor is another term for display screen. The term monitor, however, usually refers to the entire box, whereas display screen can mean just the screen. Without a monitor your computer could and would work, but you could not really see if it was trying to tell you anything.

The printer is piece of equipment that is optional to have in most cases. A printer is an output device that prints text or illustrations on paper. There are many different types of printers, such as: Daisy-wheel, Dot-matrix, Ink-jet, Laser, LCD & LED, Line printer, Thermal printer. Other ways to classify printers are speed, quality, graphics, and fonts.

Input/Output Devices

Input/Output (I/O) devices send and receive data. The I/O devices to be defined are modems, and network cards. These are also known as communication devices, because they communicate with other computers or users.

The modem is the communication device and one of its uses is to get on the Internet. The number of bits per second of information that they can transmit and receive distinguishes modems. Commonly used modems operate at 14,400, 28,800, and 56,600 Bits Per Second (BPS). Now we also have cable modems and DSL modems, and these have a much faster BPS rate.

Network cards are what connect your computer to others at your house or at work. When computers are connected to networks directly, they require special hardware called network cards to allow them to "talk" to the network, transmitting and receiving data.

Storage Devices

Storage devices are just what the name implies. They store information that is put into them using input devices. These include: hard drives, floppy drives, CD-RWs, zip drives, and internal memory components. There are several ways to describe the difference between the different types of storage devices. Here are the ways I will show how they differ: Capacity, Magnetic or Optical, Removable or Non-removable, Readable/Writable or Read only, and Transfer rate. You will need to know what a MB and GB is to understand the following section. Mega Byte (MB), Giga Byte (GB).

The smallest of the devices listed is the floppy drive. The size of the disk or diskette is roughly 3.5" x 3.5"(this is why they are called 3x5 floppies at times). The floppy is a magnetic, removable, Readable/Writable diskette, and it hold anywhere from 1.44 MB to 100 MB. It has a slower transfer rate than most of the other storage devices.

The second smallest is the zip drive. The zip disks are just like the floppy magnetic, removable, Readable/Writable, and they hold between 100 MB to 1 GB. The rate of transfer is faster than that of the floppy drive in most cases. The disks are thicker than the floppy disks but are not as wide and tall.

The second largest is the CD-RW. The CD-RW stands for compact disk re-writable. To be able to use this type of compact disk you have to have a CD-RW drive, and a program which takes information from where ever you tell it to and puts it on the CD (compact disk). CD-RW's are optical, removable, readable/writable sometimes, and also read only sometimes depending on the disk. Right now CD-RW's can hold up to 700 MB of data. The transfer rate of CD's is fast compared to that of the floppy and the zip drive.

The largest of them all is the hard drive. Hard drives are magnetic, readable/writable, and in most cases non-removable. Hard drives can be as small as 1 GB or up to about 120 GB. The hard drive has the fastest transfer rate of all the storage devices listed here.

Last but not least is Internal Memory Components. These components include RAM, ROM, and Registers.

Random Access Memory (RAM). In common usage, the term RAM is synonymous with main memory, (the memory available to programs). For example, a computer with 8 MB of RAM has approximately 8 million bytes of memory that programs can use.

Read-Only Memory (ROM). "ROM refers to special memory used to store programs that boot the computer and perform diagnostics." Most personal computers have a small amount of ROM (a few thousand bytes). In fact, both types of memory (ROM and RAM) allow random access. To be precise, therefore, RAM should be referred to as read/write RAM and ROM as read-only RAM.

A register is a special high-speed storage area within the CPU. All data must be represented in a register before it can be processed. For example, if two numbers are to be multiplied, both numbers must be in registers, and the result is also placed in a register. (The register can contain the address of a memory location where data is stored rather than the actual data itself.)

The numbers of registers that a CPU has and the size of each, help determine the power and speed of a CPU. For example a 32-bit CPU is one in which each register is 32 bits wide. Therefore, each CPU instruction can manipulate 32 bits of data.

Usually, the movement of data in and out of registers is completely transparent to users, and even to programmers. Only assembly language programs can manipulate registers. In high-level languages, the compiler is responsible for translating high-level operations into low-level operations that access registers.

Processors

Processors are the most essential part of the computer. When discussing computers, the word "processing" deals with what happens in the computer's Central Processing Unit (CPU). Programs are written to give the CPU a set of instructions to follow to accomplish a specific goal or task. Computers are sometimes called 486's, Pentiums, etc after the name of their CPU. There are several ways in which a processor plugs into the computer.

Operating Systems

Operating Systems (OS) is how your computer puts everything together and makes your computer more user friendly. Some well-known OS are Windows, Mac, Linux, and Unix.

A lot of people throughout the world use Windows made by Bill Gates. Window 3 was the first OS that Bill Gates had ever made. Windows uses GUI (graphic user interface), which uses graphics and buttons and other things that the mouse can "click" on. This allows the user to see what he or she is doing.

The first graphical user interface was designed by Xerox Corporation's Palo Alto Research Center in the 1970s, but it was not until the 1980s and the emergence of the Apple Macintosh that graphical user interfaces became popular. This is why when Bill Gates used the GUI for his OS that Mac tried to sue. They lost because they did not invent it they only made it popular. Comparing Mac and Windows is like comparing apples (Mac) and oranges (Windows)

The Unix is used on big servers because Windows can't cut it when the going gets tough. Unix was invented in the late 60's by AT&T. Linux is an open source version of it.

Computers are a very complicated piece of machinery. Computers are part of our everyday lives, and if we ever have a major computer problem around the world we would still be able to live, but life would be a lot harder and without as many conveniences. The amount of information I have given you I hope sets you on your way to a better understanding of computers.