In computer knowledge base, for some non-majors in college students is concerned, it has been a pain in their hearts, and for technical education students, many students after work, is also aware of shortcomings and lack the knowledge of their own, want to go back Bubu basics. Many courses on computer-based content complicated, but whether it is books or university courses, are a bit out of work. In particular, numerous and basic computer knowledge and want to learn from zero or review are time-consuming.
In view of this, this series of articles will take you faster to make up the necessary basic knowledge of programming, covering the three basic computer knowledge areas: computer composition principle, operating systems, computer networks, these are college computer courses inside the most important content. The content of the article and do a refining summary, abandoned as a programmer does not need knowledge.
The purpose is to:
- Help you form a computer architecture knowledge
- Help you understand the underlying principles of computer
- Help you learn where the practical work of outstanding design
Benpian input and output device of the computer composition principle of computer
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Input and output devices
Input and output devices, also known as IO devices, is one of the key external device to the computer, and the computer can be used interchangeably body, played a role in the interaction between man and machine.
The input device is the computer input data and device information for the original data and the processed data a program entered into a computer, common with a keyboard, mouse, camera, scanner, light pen, handwriting input board, voice input device Wait. The computer is capable of receiving a variety of data, either numerical data may be a variety of non-numeric data, such as graphics, images, sound and so can be input to the computer via an input device of a different type, for storing, processing and output.
Output device, or the processing is the calculation results or the intermediate results in various forms of human recognizable, such as numbers, symbols, letters, etc. represented, a common display, a printer, an image output system, speech output system, magnetic recording apparatus Wait. A display computer graphics output devices essential, it is the role of converting a digital signal into an optical signal, so that text and graphics displayed on a screen; a major output device is a printer on the PC, the program which , data, character graphics printed on paper.
The communication method CPU and an IO device
Two ways: interrupt, DMA (direct memory access).
Program interruption
When the peripheral IO device is ready, it will send an interrupt signal to the CPU, the CPU has a special internal circuit in response to an interrupt signal when the CPU receives an interrupt signal, it will suspend the task at hand, instead of processing the peripheral IO devices work after IO devices and other peripherals task processing is completed, CPU will continue the original work.
Program interruption notification device provides a low-speed CPU in an asynchronous manner, so that, taking into account the CPU can respond to low-speed devices at the same time, high-speed operation. However, the CPU is interrupted frequently work is not a good way, this will reduce the efficiency of CPU.
DMA (direct memory access)
The DMA, but also a hardware device that is connected directly to main memory and IO devices, the CPU is not involved during operation. When the main memory and IO devices to exchange information, without interrupting the CPU, the CPU can be used to improve efficiency.
