Current day computer systems consist of two main components: software and hardware. Computer software refers to the code instructions that tell the computer what to do, while computer hardware refers to the physical parts of the computer that you can see and touch. There are five parts of computer hardware that can be found in most computer systems, from smart phones to desktop computers: processor, primary storage, secondary storage, input devices and output devices.
Computer Processor and Primary Storage
The computer hardware definition includes both internal and external devices. The internal devices are often referred to as components. They reside on the motherboard, which is the computer's main circuit board. The central processing unit, or CPU, is the so-called brain of the computer that interprets code instructions and controls all the computer's operations. It also performs simple calculations and moves data in and out of memory.
The CPU uses primary storage, also referred to as main memory or random access memory (RAM), to store program instructions and any data the instructions may require. The information stored in RAM is temporary in nature and is retained only while the current program is running. When you turn off the computer, primary memory is cleared. Permanent memory is available in secondary storage.
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Computer Secondary Storage
Secondary storage takes place on permanent memory devices like hard drives and flash drives. Data stored on these devices is retained even when the computer is turned off. Many hard drives are called internal because they're located within the computer's case. There are also external hard drives that connect to a computer via a USB port.
Flash drives are faster than hard drives and are used for internal persistent storage in smart phones and tablets. Like external hard drives, external flash drives can be connected to computers via USB ports. This type of flash drive may also be referred to as a thumb drive or jump drive.
Computer Hardware Input / Output Devices
A computer has input and output devices for communication with the outside world. An input device lets you enter data into the computer. One of the most common hardware input devices is the keyboard, which is used for text input. The mouse and touch screen are also input devices; their purpose is to allow a computer user to move a cursor on a screen. Cameras, scanners and microphones can also be used for computer input of specific types of data. Display monitors, speakers and 2D and 3D printers are some of the most common computer output devices.