A computer is a system for processing information. It receives data from various sources and combines it with instructions to produce the desired results. Early computers in the 1960s used punch cards for inputs and produced results on monitors or special computer paper. Apple produced the first consumer computer with a graphical user interface in 1976. With the more powerful processors available today, you can add other items to expand the computer's functionality. Connected to networks and the Internet, computers can receive, process and send information in many different ways.
Modern computers receive their data through various components. When you post a message on a social networking site, the computer first accesses the website through its Internet connection via the modem. You use your keyboard to enter the message text. If you want to post a picture or video clip, you may take that from a data storage component such as a hard drive, from a CD or DVD via your computer's optical drive or from a memory stick or card via a USB port or card reader. Throughout this input process your mouse clicks on icons and buttons to deliver commands.
Before it can appear in your message, the computer must process the input data and change it into the correct code and format. The computer carries out the processing inside the main computer box or central processing unit. The CPU has plugs for all the input and output parts and contains the microprocessor, memory and network, USB, video and audio interfaces on the motherboard or on separate electronic cards. The CPU also includes the hard drive, which stores programmed instructions in the computer software on the drive. The CPU uses these instructions to process your input in the microprocessor, temporarily storing information in the memory before sending it to the interfaces for output.
Once processed, your message is ready for posting. The CPU sends it to the network interface, which sends it to the modem -- or first to your router, either through a cable or a wireless connection, and the router directs it to the modem. The modem sends it out to the website and your message appears. Your computer shows you this process by displaying it on your monitor via the video interface. If you want to print out your message, your CPU will send it to the printer via the USB interface. If you want to play your video, your CPU will display the picture on the screen via the video interface and send the sound to the speakers via the audio interface.
Additional input/output devices can extend the computer's functions. Microphones, webcams and scanners help input audio signals and video or graphics. External drives store your data outside the CPU and let you transfer it to other computers. Projectors output large images for viewing in a group. These peripherals typically work via the USB interface and most computers have several USB ports to allow for the connection of various peripheral devices.
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