A Turing machine
British mathematician Alan Turing in 1936 proposed the "Turing machine" theory. "Turing machine" Imagine an infinitely long piece of paper with squares on a piece of paper, each box can store a symbol, a note left or right movement.
Turing machine can do the following three basic operations:
- Head pointer points to read symbols.
- Characters from the box changes.
- The tape left or right, in order to modify the value of its adjacent blocks.
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The basic idea is to use Turing machine to simulate people to math with pen and paper process, he put this process as following two simple actions:
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1, a piece of paper to write or erase a symbol;
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2, the focus moves from one position to another position of the paper
Two computer science
Disciplinary computer science: its basic ideas ranging from theoretical research, engineering design model to abstract three, although three different, but they all follow certain steps: the theory is the fundamental mathematics. Abstraction is fundamental natural sciences. Design is the fundamental project.
The meaning of Computer Science: Computer Science is the discipline of information processing
The second chapter begins with three
Calculated from the chapter to achieve the desired physical conditions have / hardware environment, including hardware and architecture angle, successively introduced the personal computer, computer system architecture, a mobile terminal, a computer network, cloud computing and networking.
2.1 Von Neumann architecture is the foundation of modern computers
2.1.2
CPU: Central processing unit or also to the central processing unit, by a controller, operator, and registers. Register temporarily holds data to be processed and the arithmetic processing result.
Processor Memory: Acronym memory for storing a program to be executed and corresponding data
External memory: a hard disk, an optical disk, U disk, mobile hard disk
Input devices: keyboard, mouse, scan screen, touch screen
Output devices: displays, printers, plotters
2.2
The system structure of the computer:
User Layer <- high-level language level <- layer assembly language <- operating system layer <- machine language level <- control layer <- digital circuit layer