What is a computer?
Very basically, a computer is a collection of hardware and software that allows you to take various types of input, manipulate them, and turn them into various types of output. The computer's main uses today include information processing of all kinds, storing that information, running various office applications, sending and receiving email, running and maintaining databases, accessing the internet, and running thousands of different types and designs of machinery and systems. Personal computers come in several different styles such as PCs, laptops, tablets, and hand-helds.
There are several concepts that should be understood to make your personal computer use easier and more productive. Among them are-
Input-- The computer takes input from various devices, manipulates it, and outputs it in a number of ways. Input devices include the keyboard, mouse, CD/DVD player, floppy drive, tape drive, modem, audio devices, ethernet adapter, and various types of ports including USB, serial, Firewire, and parallel.
Processing-- The processor takes all the 1's and 0's of the data stream and processes them into useful information. It also controls the flow of data throughout the motherboard and between the assorted devices connected to it. A simple example of processing would be the calculation of 2 + 2 = 4 from the calculator program.
Output-- Depending on what the user is doing, the computer can produce many different types of output. Some output devices include the monitor, speakers, modem, various ports, floppy drive, ethernet adapter, CD/DVD drives, printers, and even other computers and the internet.
Storage-- The computer takes the various types of information and stores them for future use. Temporary storage is in RAM, or Random Access Memory. Permanent storage is on the hard drive, tape drive, CDs and DVD's, floppy drive, or other external devices.
A File is the basic unit of storage and manipulation on a computer. Data is stored as files- for example, a resume. Files are usually grouped together and stored in folders and directories.
On a computer, software is really what runs the show. The software is the real intelligence and it tells the hardware what to do. Software consists of what are called programs. Programs are a collection of files that work together to do a specific task. For example, Windows is a program. It runs as a GUI, or Graphical User Interface. This allows the computer user to see the programs as picture and text based instead of just text on a plain background. Nearly everything done on the modern computer is done through GUI programs.
Computer hardware consists of the following-
Computer case-- This is the actual box that holds the motherboard, power supply, and all the components.
Power supply-- This unit supplies the electrical power to run everything. It also contains a fan that pulls cooling air through the case to remove the heat generated by the processor.
Motherboard-- Everything in the computer either sits on, or is connected to, the motherboard. It contains the processor, memory, chipsets, video, audio, battery, different jacks, and contains the Buss that connects everything together.
Parts of the motherboard-
Processor-- This is like the engine of the computer. It processes all the bits of data very quickly and works with memory to handle the Input/Output duties. Processor speed is measured in gigahertz, which stands for billions of cycles per second.
Memory-- The RAM, or memory modules, are where all the programs are running. Data shuttles back and forth very quickly between the memory and the processor. The memory is emptied when the computer is turned off or Windows is restarted. RAM stands for Random Access Memory, meaning that data may be constantly written to and retrieved from this memory.
The Buss is the network of pathways between the various devices. It consists of the actual printed circuits on the motherboard. Various data cables are also used to physically connect the motherboard to different devices, which are not directly attached to it.
Expansion slots-- These are slots which allow the plugging in of expansion cards to the computer such as improved video, more ports, and different types of drives. These cards are sometimes called daughterboards and they can consist of different architectures such as ISA, PCI, and AGP.
Battery-- The battery provides a trickle of power to the motherboard, mainly to keep the clock running and keep track of time.
Chipsets-- These are various memory chips on the motherboard that control different devices such as video, keyboard, mouse, audio, network adapter, etc. Collectively, these are known as the BIOS. The BIOS contains all the default settings for the various computer hardware devices, and basic features such as processor speed, input device settings, buss types, etc.
Ports-- The ports supply the connection points for the various external I/O devices. There are ports for the keyboard, mouse, monitor, modem, printer, audio devices like headphones, speakers, and microphones, USB and Firewire devices, and ethernet.
Hard drive-- The hard drive basically consists of spinning disks with one or more read heads. It stores all the information in the form of files and directories and holds the operating system files as well. Hard drives may be built with different types of buss, including SCSI, ISA, or SATA.
Floppy drive-- The floppy drive writes and reads data to and from a floppy disk. Because of its limited storage capacity, the floppy disk is being phased out.
CD/DVD ROM drives-- These drives play the data from a CD or DVD disk. They are commonly used for music and video storage. A CD or DVD Burner allows the computer to create copies of data on these media. These devices are considered to be ROM, or Read only Memory, meaning that the data on them can only be read and not written to.
Monitor-- The monitor displays information it receives from the graphics adapter. There are two types of monitors- CRT or cathode ray tube, and LCD or liquid crystal display. Various adjustments are possible such as brightness, contrast, color, position, etc. Resolution on the video monitor is adjusted through Windows.
Keyboard-- The keyboard is the standard input device. It issues commands, types letters and numbers, as well as performing many functions through the control and special keys.
Mouse-- The mouse is used to provide different types of input to Windows and other GUI programs such as point and click, drag, select, etc. It may contain left and right click buttons as well as a scroll wheel.
Joysticks and game devices-- There are many different styles of these controllers and they enable manipulation of objects in computer games.
Basic sequence of what's happening when the computer starts-
The switch is turned on and power flows to power supply.
The fan starts and power is supplied to motherboard.
The BIOS loads the video driver so you can see the rest of the sequence on the monitor.
Computer BIOS goes through its startup routine, called the POST or power-on-self-test, which checks the various hardware devices.
If all the hardware checks out OK, the BIOS looks for the hard drive with the operating system startup files.
The startup files are located and loaded into memory and the startup sequence is initiated.
Windows starts up and displays on the monitor.
Other programs that are in the startup directory start at this time.
Computer is ready to use.
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