Computer Systems
Computer is an electronic device that stores, retrieves, and process data, and can be programmed with instructions. A computer is composed of hardware and software, and can exist in a variety of sizes and configurations.
Computer Applications
To begin with you must understand the impact of computers in the world today. computers are affecting our lives in one way or the other. Airline and railway reservations, telephone and electricity bills, banking, medical diagnoses, weather forecasts... the list of services using computers is almost endless.
Generations of Computer
First Generation : - 1940-1956 Vacuum Tubes
The first generation computers used valves leading to huge size and cost. The UNIVAC and ENIAC Computers are examples of first generation computing devices.
The UNIVAC was the first generation commercial computer delivered to a business client, the U.S. census Bureu in 1951.
Second Generations
The Second Generations computer used transistors. In a spam of ten years, transistors that were more efficient and cheaper replaced valves.
Third Generations
The third generations computers used Integrated Circuit(IC). In the early sixties, a major breakthrough was achieved when hundreds of transistors could be on a single silicon chip. This IC became the basis of the third generation.
Fourth Generation : - 1971 Present: Microprocessors
The Fourth Generation computers used microprocessors with the introduction of very large scale Integration(VLSI), thousands of transistors could be placed on a single chip.
Fifth Generation : - Present and Beyond: Artificial Intelligence
The fifth generation computer tries to infuse intelligence into computers. The development intelligence into computers. The development of those computers is still in its infancy.
Computer Systems
The personal computer (PC) is although the most popular computer system, there are other computer systems too, which are categorized on the basis of cost and performance.
Personal Computers or Micro Computers
The micro computer is also known as PC. The most popular form of the computer in use today is probably PC.
The PC can be used for various applications and, in fact, there are millions of PCs already in use by individuals and organizations.
Minicomputers
A popular computers system is the minicomputer which is also small desktop model expensive than a PC and surpasses it in storage capacity and speed. While most PCs are oriented towards single users, mini systems are usually designed to simultaneously handle the needs of multiple users, i.e. more than one person use a minicomputer at the same time.
Mainframe Computers
A Mainframe Computers form of a computer system that is generally more powerful than a typical Minisystem. Mainframes themselves may vary widely in cost and capability. They are used in large organizations for large-scale jobs.
Super Computer
At the end of the size and capability scale are the supercomputers. These systems are the largest, Fastest and the most expensive computers in the world. They are used for Bio-medical research, weather forecasting, chemical analysis in laboratory, complex scientific, and defense applications.
Components of a PC system
Hardware
Input-Output Devices
The input devices are used to give instructions to the computer. For example keyboard and mouse.
The output devices are used to display output of an operation. For example, monitor and printer.
Mouse
A mouse is a small device that is connected to the system unit by means of a long wire. This another input device, whose movement causes the corresponding movement of a pointer on the screen. It usually has two or three buttons using which the user can select options from the screen.
VDU
Data that has been processed needs to be diaplayed to the user. This is done using the monitor or the VDU. The VDU is similar to a TV Screen and can display both text and graphic images. The display can be either in black & white or, color.
Printer
The output on the VDU cannot be stored for later reference. For a permanent output, you would require a printer that is also a common output device. Using the printer, you can obtain output on paper. Printers are capable of printing at very high speeds. The printers commonly used with PC are the dot-matrix printer, ink-jet printer and the Laser Printer.
Microphone
A Microphone is an input device that allows a user speak to the compiler to enter data and instructions in to computer or it is used to record sound.
Joystick
A Joystick is a pointing device with a vertical lever mounted on a base. It is mainly used for computer games and ultrasound scanner is hospitals.
Scanner
A Scanner is an input device used to Capture information, such as photographs and documents on paper and translate the information in to a raster (bitmap) computer image.
Speakers
You can use speakers on a multimedia machine to listen to the sound files, which can be audio, recorded by a microphone or audio CDs.
Processing Devices
The processing devices are used to process the instructions given to the computer. Microprocessor is an example of processing devices.
System Unit
When data is input to a computer, it is processed and an input is produced on the output device. Processing takes place in system unit. The component of the system unit that is involved in the actual processing is the microprocessor. Another component of the system unit is the internal storage.
C.P.U
C.P.U is the brain of the computer and is placed inside the system unit. The C.P.U chip is responsible for processing data, storing data and retrieving the information.
Storage Devices
Primary Storage Devices - The primary storage devices for a computer is Random Access Memory(RAM). RAM is a volatile storage device.
Secondary Storage Devices - Some of the examples of secondary storage devices include hard disk, floppy disk and compact disk. Data stored in these devices is stored permanently.
Hard Disk - The Hard Disk is a high storage capacity disk and is permanently placed inside the computer. Normally there is only one Hard Disk for a computer but if required you can add extra hard disk to your computer.
Floppy Disk - The Floppy Disk is a portable secondary storage device with which you can copy the data from one machine to another. A removable storage medium that is used in conjunction with a floppy drive.
Compact Drive - The Compact Disk is also a portable storage device. You use a CD writer to store data can on the compact disk. The data can be read using a CD drive.
Software
A PC is incapable of performing any task with the hardware alone. It requires instructions to function as desired like data instructions are also entered via the input devices like keyboard, mouse and joystick.
A set of instructions is called a program. A set of program written to achieve a common objective is called software.
We can categorize software in to two types.
1) Application Software
2) System Software
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