Computer+Systems

 A computer is an electric device that can preform tasks and calculations to provide logical information based on the instructions that have been given to it.

Computers vary in type, size, speed, and capability. Below are some of the most common computers. __**Memory **__ **__ Hardware __** This is the physical parts of a computer system and includes four main components: input devices, processing unit, output devices, and storage devices.
 * __Types of Computers __**
 * **Desktop Computer** is a personal computer (PC) in a form intended for regular use at a single location, as opposed to a mobile laptop or portable computer . Prior to the wide spread of microprocessors, a computer that could fit on a desk was considered remarkably small.
 * **Laptop computer**  is a personal computer designed or mobile use and small enough to sit on ones lap while in use. A laptop integrates most of the typical components of a desktop computer, including a display keyboard, pointing devices, speakers, and often including a battery, into a single small and light unit. The rechargeable battery is charged from an ac adapter and typically stores enough energy to run the laptop for two to three hours in its initial state, depending on the configuration and power management of the computer.
 * **Hand-held computer** is a computer that is small enough to be held in ones hand .Although extremely convenient to carry it has not replaced any of the other types of computers. Hand-held computers also include personal digital assistant (PDA). This type of computer is most commonly used to store appointments, phone numbers, task and various other data commonly needed while away from home or the office.
 * **RAM:** is a random access memory. RAM provides space for your computer to read and write data to be accessed by the CPU.
 * **ROM:** is the read-only memory. ROM is the memory whose contents can be accessed and read but can not be changed.
 * **Output Devices:** are hardware that feeds information to the user. Output devices give the user information in various ways. Some ways are through soft copy and hard copy. **Soft copy** is information given from a monitor or from speakers, a **hard copy** is the information given in a physical form from a printer. Some examples of Output devices are:
 * **Printers -** The printer provides your information in a physical form.
 * **Impact printer**- Refers to a class of printers that work by banging a head or needle against an ink ribbon to make on the paper. This includes dot matrix printers, daisy-wheeled printers, and line printer.
 * **Nonimpact Printer**- the laser and ink-jet are nonimpact printers. The distinction is important because impact printer tend to be considerably noisier than nonimpact printer but are useful for multipart forms such as invoice.
 * **Monitor-** The monitor could show you various forms of soft copy. For example, text or in a graphic form.
 * **Speaker-** The speaker only provides you with audio.
 * **Projectors-** It projects whatever is on your monitor screen.
 * **Input Devices:**
 * **Keyboard:** is a way to input numbers and letters into different applications or programs. A keyboard also has special keys that help operate the computer.


 * **Mouse:** used to open and close files, navigate web sites, and click on commands when using different applications [[image:mouse.jpg align="center"]]
 * **Scanner**: used to copy pictures and save as files on your computer.


 * **Digital Camera:** most are used during live conversations. It transmits a picture from one computer to another, or to record shot videos.
 * **Microphone:** used to record sound, then saved as a sound file on your computer.
 * **Modem:** used to convert digital information to analog by modulating it on the sending end, and demodulating the analog information into digital information at the receiving end.
 * **Storage Devices:** A storage device is a memory device: a device that preserves information for retrieval.
 * **Floppy disk:** is an increasingly obsolete data storage medium that is composed of a disk of thin, flexible magnetic storage medium encased in a square or rectangular plastic shell.
 * **USB flash**: memory is a data storage device integrated with a USB interface.
 * **Hard drive:** is a computers main storage media device.
 * **CD-ROM:** is a compact disk that is used with a computer (rather that an audio system)
 * **Zip drive:** is a medium-capacity removable disk storage system, introduced by Lomega in late 1994.
 * **DAT:** is a digital audiotape: a digital tape recording of sound.

__**Software**__
 * **Application Software:**
 * **Database** is a collection of data. A computer database relies on database software to organize the data and enable the database users to achieve database operations. Database software allows the users to store and retrieve data from databases.
 * Oracle
 * MS Access
 * **Word processing**: This software enables the users to create and edit documents.Examples:
 * <span style="color: rgb(0,0,0);">MS-Word
 * <span style="color: rgb(0,0,0);">WordPad
 * <span style="color: rgb(0,0,0);">Notepad
 * <span style="color: rgb(0,0,0);">And other text editors.
 * <span style="color: rgb(0,0,0);">** Spreadsheet Software: ** Spreadsheet software allows users to perform calculations. They simulate paper worksheets by displaying multiple cells that make up a grid. Examples:
 * <span style="color: rgb(0,0,0);">Excel
 * <span style="color: rgb(0,0,0);">Lotus 1-2-3
 * <span style="color: rgb(0,0,0);">Apple Numbers
 * ** Presentation Software: ** The software that is used to display information in the form of a slide show is known as presentation software. This type of software includes three functions, namely, editing that allows insertion and formatting of text, methods to include graphics in the text and a functionality of executing the slide shows.
 * MS PowerPoint
 * ** Graphic ** -are presentation on the surface such as wall, computers or stones to brand illustrations. Examples are photographs, Drawing, line arts, graphs.
 * MS Paint
 * Photoshop
 * Fireworks
 * <span style="color: rgb(0,0,0);">**System Software:**
 * <span style="color: rgb(0,0,0);">** MS-Dos ** was made by Microsoft. It was the most commonly used member of the DOS family of operating systems and was the main operating system for personal computers during the 1980s. M-DOS came out before MS-DOS, it was designed and copyrighted by Microsoft in 1979. It was replaced on consumer desktop computers by operating systems offering a graphical user interface (GUI).MS-DOS was known before as **QDOS** (**Q**uick and **D**irty **O**perating **S**ystem) and 86-DOS
 * **Mac OS 8.6**
 * ** UNIX ** was one of the first operating systems to be written in a high-level programming language, namely C. This meant that it could be installed on any computer for that had a C compiler. It wasn’t expensive because antitrust regulations kept Bell Labs from marketing it as a full-scale product. UNIX was designed to be a small, flexible system used exclusively by programmers.
 * ** Windows 98 ** had two main versions, named 98FE and 98SE. The FE & SE stand for first and second editions. 98 was released on June 25 1998, with 98SE the following year (1999) on May 5th. Windows 98 supported upgrading from Windows 3.1x and/or Windows 95. Windows SE could upgrade from Windows 3.1x, Windows 95 or Windows 98 FE.


 * ** Windows 7 ** is the latest version of Microsoft Windows, a series of operating systems produced by Microsoft for use on personal computers, including home and business desktops, laptops, tablet PCs and media center PCs. Windows 7 was released on July 22, 2009, with general retail availability set for October 22, 2009 less than three years after the release of Windows Vista. Windows 7's server counterpart, Windows Server 2008 R2, is scheduled for release at about the same time.
 * ** Windows Vista ** is a line of operating systems Windows Vista is a line of operating systems developed by Microsoft for use on personal computers including home and business desktops laptops, tablet PC, and media center PCs. Windows Vista has many features and changes which will be easier to use and be more helpful. It includes an updated graphical user interface and visual style. Windows vista has a redesigned search functionality and multimedia includes Windows DVD maker. Vista also includes a redesigned networking, audio, print, and display sub-systems. Windows Vista helps you share files and media on a much easier level.