THE COMPUTERA computer system is the synthesis ofhardware and software. A typicalcomputer system employs a computerthat uses programmable devices to store,retrieve, and process data.
The personal computer or PC exemplifiesone example of a computer system. AnAutomatic Teller Machine (ATM) is anotherexample of a computer system.The Internet does NOT exemplify acomputer system per se, but rather anetwork of computer networks.
1. Hardware•Computer hardware is the physical part of a computer,including the digital circuitry, as distinguished from thecomputer software that executes within the hardware.•The hardware of a computer is infrequently changed, incomparison with software and data, which are "soft" inthe sense that they are readily created, modified orerased on the computer. Firmware• is a special type of software that rarely, if ever, needs tobe changed and so is stored on hardware devices such asread-only memory (ROM) where it is not readily changed(and is therefore "firm" rather than just "soft").
2. Uses•Personal computers are normally operated byone user at a time to perform such generalpurpose tasks as word processing, internetbrowsing, e-mail and other digital messaging,multimedia playback, video game play,computer programming, etc.
3. Categories of Personal computers as to size and portability:a. Desktop ComputerThis is an independent personal computer that ismade especially for use on a desk in an office or sused mainly to distinguish this type of personalcomputer from portable computers and laptops, butalso to distinguish other types of computers like thePDA, server or mainframe.
All-in-one• All-in-one computers are desktop computers thatcombine the monitor into the same case as the CPU.•The term, "all-in-one" was initially associated withDigital Equipment Corporations VAX "all-in-one"software which provided a common menu tochoose: email, spreadsheet, database, file system,etc
b. LaptopA laptop computer or simply laptop (alsonotebook computer or notebook) is a smallmobile personal computer, usually weighingfrom one to three kilograms, depending onsize, materials and other factors.
.Personal Digital AssistantPersonal digital assistants (usually abbreviated to PDAs) arehandheld devices that were originally designed as personalorganizers, but became much more versatile over the years.A basic PDA usually includes date book, address book, tasklist, memo pad, clock, and calculator software. Newer PDAsalso have both color screens and audio capabilities, enablingthem to be used as mobile phones (PDA Phone), webbrowsers or media players. Many PDAs can access theInternet, intranets or extranets via Wi-Fi, or Wireless Wide-Area Networks (WWANs).
d. Portable Computer A Portable computer is a computer that is designedto be moved from one place to another (in other words,it is a computer that is portable). Portable computers,by their nature, are microcomputers. Early portables were unkindly referred to as"luggables," referring to their great size and weight(owing partly to the need to include a full-blown CRTmonitor, as LCD technology was not yet mature).
e. Tablet PCA tablet PC is a notebook- or slate-shaped mobilecomputer.Its touch screen or digitizing tablet technology allows theuser to operate the computer with a stylus or digital peninstead of a keyboard or mouse.A user can input text using the built-in handwritingrecognition, on-screen (virtual) keyboard, speechrecognition, or a physical
f. Wearable computerA wearable computer is a small portable computerthat is designed to be worn on the body during use.In this wearable computers differ from PDAs, whichare designed for hand-held use, although thedistinction can sometimes be a blurry one.
Wearable computers are usually eitherintegrated into the users clothing or can beattached to the body through some othermeans, like a wristband.They may also be integrated into everydayobjects that are constantly worn on thebody, like a wrist watch or a hands-free cellphone.
4. SoftwareThe software is the information that thecomputer uses to get the job done.Software needs to be accessed before it can beused. There are many terms used for process ofaccessing software including running,executing, starting up, opening, and others.
The three basic types of software are:commercial, shareware and open sourcesoftware. Some software are also released into thepublic domain without a license.
•Commercial software comesprepackaged and is availablefrom software stores andthrough the Internet.
• Sharewareis software developed by individual and smallcompanies that cannot afford to market theirsoftware world wide or by a company that wants torelease a demonstration version of their commercialproduct. You will have an evaluation period in which you candecide whether to purchase the product or not.Shareware software often is disabled in some wayand has a notice attached to explain the legalrequirements for using the product.
•Open Source softwareis created by generous programmers and released into thepublic domain for public use. There is usually a copyrightnotice that must remain with the software product. Open Source software is not public domain in that thecompany or individual that develops the software retainsownership of the program but the software can be usedfreely. Many popular Open Source applications are beingdeveloped and upgraded regularly by individuals andcompanies that believe in the Open Source concept.
Types of MemoryRAM - random access memory, also known asRead-Write memory, can have new data writteninto it as well as stored data read from it. Adrawback of RAM is that it requires electricalpower to maintain data storage. If the computeris turned off or looses power, all data stored inRAM is lost, unless if the data was saved to diskROM - read-only memory, computer memory onwhich data has been prerecorded; once data hasbeen written onto a ROM chip, it cannot beremoved and can only be read
5. Disk and StorageDisks are used to store information.Information on computers are storedin files. The size of a file is measured inbytes.
A byte is approximately one character (letter a,number 1, symbol ? etc....).•About a thousand bytes is a kilobyte (KB).•About a million bytes is a megabyte (MB).•About a billion bytes is a gigabyte (GB).
A byte is made up of 8 bits. A bit is simply anon or an off signal which passes through thecomputers circuitry. Every piece of softwarecan be broken down into a series of on or offsignals or its Binary Code.•Floppy disks are still a common way oftransporting information (such as bringing fileshome from work) but compact disks (CDs) andDigital Video Devices (DVDs) are becomingmore popular. Most software are sold on CDs.• Hard disks are the most common storagedevice.
Basic Computer OperationsHow Computers WorkInput: Information and programs are enteredinto the computer through Input devices such asthe keyboard, disks, or through other computersvia network connections or modems connectedto the Internet. The input device also retrievesinformation off disks.
Output: Output Devices displaysinformation on the screen (monitor) or theprinter and sends information to othercomputers. They also display messagesabout what errors may have occurred andbrings up message or dialog box asking formore information to be input. The outputdevice also saves information on the diskfor future use.
Processing: The CPU or central processing unitis sometimes called the Control Unit and directsthe operation of the input and output devices.he Coprocessor or the Arithmetic-Logic Unitdoes arithmetic and comparisons. The memoryor RAM temporarily stores information (filesand programs) while you are using or workingon them. The BIOS or basic input/outputsystem controls the dialogue between thevarious devices.