Computer An electronic device, operating under the control of instructions stored in its own memory unit, that can accept data (input), manipulate the data according to specified rules (process), produce information (output) from the processing, and store the results for future use.
Information Processing Cycle STORAGEINPUT PROCESS OUTPUT
INPUT• The collection of raw data from the outside world so it can be put into an information system. Putting the acquired data into the information system.Examples:• The payroll clerk collects workers timecards so she knows how many hours each person worked that week and types the hours from the timecards into a spreadsheet• Collecting jokes for a joke book and typing jokes into a word processor.• Using a form on a website to collect visitors opinionsTypical input devices:• Keyboards, mice, flatbed scanners, bar code readers, digital data tablets (for graphic drawing), electronic cash registers
PROCESSINGA process is a program that is running on your computer. This can beanything from a small background task, such as a spell-checker or systemevents handler to a full-blown application like Internet Explorer orMicrosoft Word. All processes are composed of one or more threads. The most important part of these components is the central processingunit (CPU) also called the processor. The CPU is the brain of yourcomputer it is the key component in interpreting computer programinstructions and processes data.The next most critical element of a processing is RAM, often referred to as"primary storage" or "main memory". Random Access Memory (RAM)temporarily stores information that the CPU uses while the computer is onand is erased when the computer is turned off.
Output• In information processing, output is the process of transmitting the processing information• Essentially, output is the presentation of any data exiting a computer system. This could be in the form of printed paper, audio, video. In the medical industry this might include CT scans or x-rays. Typically in computing, data is entered through various forms (input) into a computer, the data is often manipulated, and then information is presented to a human (output).
Typical output devices:• Monitors – Pixels: Images are created with dots of lights called picture elements, or pixels. More pixels = higher resolution. Resolution is the maximum number of pixels the monitor can display – Basic VGA is a pixel grid 640 X 480 – Super VGA is 1,024 X 768 – A video card, (also referred to as a graphics accelerator card, display adapter, graphics card, and numerous other terms), is an item of personal computer hardware whose function is to generate and output images to a display .• Printers – Laser - laser beams bond toner to paper – Ink jet - fine stream of ink – Dot Matrix - pins & ribbon
Storage• Computers usually have one or more disk drives, commonly referred to as a hard drive— devices that store information. The disk preserves the information even when your computer is turned off. All computers have a hard disk drive that can hold massive amounts of information; they usually serve as your computers primary means of storage, holding almost all of your programs and files. The hard disk drive is normally located inside the system unit.
Examples of mass storage devices• Disk storage – hundreds of thousands of cycles latency, but very large – Hard disks : Very fast and with more capacity than floppy disks, but also more expensive. Some hard disk systems are portable (removable cartridges ), but most are not. – Solid State Drives have no moving parts and utilize non-volatile memory chips. – Floppy Disks: (almost obsolete!)• Tertiary storage – – Optical storage: Unlike floppy and hard disks, which use electromagnetism to encode data, optical disk systems use a laser to read and write data. Optical disks have very large storage capacity, but they are not as fast as hard disks. Examples: CD, CD-R, CD- RW, DVD or DVD-R – Tapes: Relatively inexpensive and can have very large storage capacities, but they do not permit random access of data.• Flash Memory – faster than disk storage, with up to 4GB or more of data, transferring (usually) over universal serial bus (USB)
Types of Computers• Computers come in all sorts of shapes and sizes and serve a variety of purposes. Not too many years ago, computers were the size of a large room and consumed huge amounts of power. However, with the advances in technology, computers have shrunk to the size of a watch. Depending on the processing powers and sizes of computers, they have been classified under various types. Let us look at the classification of computers.Different types of Computers :•Supercomputers: Highly calculation-intensivetasks can be effectively performed by means ofsupercomputers. Quantumphysics, mechanics, weather forecasting, moleculartheory are best studied by means ofsupercomputers.
•Mainframe Computers: Large organizations use mainframes for highly critical applications. Most of the mainframe computers have the capacity to host multiple operating systems and operate as a number of virtual machines and can thus substitute for several small servers.•Microcomputers: A computer with amicroprocessor and its central processing unit isknown as a microcomputer. When supplementedwith a keyboard and a mouse, microcomputers canbe called as personal computers. A monitor, akeyboard and other similar input outputdevices, computer memory in the form of RAMand a power supply unit come packaged in amicrocomputer. These computers can fit on desksor tables and serve as the best choices for single-user tasks.
Personal computers come in a variety of forms such as desktops, laptops andpersonal digital assistants. Let us look at each of these types of computers.•Desktops: A desktop is intended to beused in a single location and are widelypopular for daily use in workplace andhome.•Laptops: Similar in operation to desktops, laptopcomputers are miniaturized and optimized formobile use. Laptops run on a single battery or anexternal adapter that charges the computerbatteries. They are enabled with an inbuiltkeyboard, touch pad acting as a mouse and a liquidcrystal display.
•Personal Digital Assistants (PDAs): It is a handheldcomputer and popularly known as a palmtop. It has a touchscreen and a memory card for storage of data. PDAs can alsobe effectively used as portable audio players, web browsersand smart phones. Most of them can access the Internet bymeans of Bluetooth or Wi-Fi communication.