The hardware system is mainly composed of CPU, memory, input and output control system and various external devices. Central processing unit (CPU) is the main component of information high-speed operation and processing, and its processing speed can reach hundreds of millions of operations per second.
Memory is used to store programs, data and files. It usually consists of fast internal memory (hundreds of megabytes or even gigabytes) and slow massive external memory (tens of gigabytes or more). Various input and output external devices are information converters between man and machine, and the input and output control system manages the information exchange between the external devices and the main memory (central processing unit).
software
Software is divided into system software, supporting software and application software. The system software consists of operating system, application program and compiler. The operating system manages and controls various software and hardware resources. Utilities are designed for the convenience of users, such as text editing. The function of compiler is to translate programs written by users in assembly language or some high-level language into machine language programs that can be executed by machines.
Supporting software includes interface software, tool software, environmental database, etc. It can support computer environment and provide software development tools. Supporting software can also be considered as a part of system software. Application software is a special program written by users according to their own needs. It runs with the help of system software and supporting software, and is the outermost layer of software system.
trait
1. Calculation: Almost all complicated calculations can be realized by arithmetic and logical operations with a computer.
2. Judgment: Computers have the ability to judge different situations and choose different processing methods, so they can be used in management, control, confrontation, decision-making, reasoning and other fields.
3. Storage: Computers can store a lot of information.
4. Accuracy: As long as the word length is enough, the calculation accuracy is not limited in theory.
5, fast: the time required for a computer operation has been as small as nanoseconds.
6. Universal: Computers are programmable, and different programs can realize different applications.
7. Ease of use: Rich high-performance software and intelligent man-machine interface greatly facilitate the use.
8. Networking: With the help of communication networks, multiple computer systems can transcend geographical boundaries and share remote information and software resources.
principle
Although computer technology has developed rapidly since the birth of the first electronic general-purpose computer in the 1940s, today's computers still basically adopt the stored program structure, that is, the von Neumann structure. This structure realizes a practical general-purpose computer.
The stored program structure describes the computer as four main parts: arithmetic logic unit, control circuit, memory and input and output devices. These components are connected by a set of flat cables (especially when a set of wires is used for data transmission with different intentions, it is also called a bus) and are driven by a clock (of course, some other events may also drive the control circuit).
Conceptually, the memory of a computer can be regarded as a group of "cells". Each "cell" has a number called an address; But also can store smaller fixed-length information. This information can be instructions (telling the computer what to do) or data (the processing object of instructions). In principle, each "cell" can store any one of them.
Arithmetic logic unit (ALU) can be called the brain of a computer. It can do two operations: the first is arithmetic operation, such as addition and subtraction of two numbers. The function of arithmetic operators in ALU is very limited. In fact, some ALUs don't support multiplication and division at circuit level at all (because users can only do multiplication and division through programming).
The second is comparison operation, that is, given two numbers, ALU compares them to determine which is larger.
Input-output system is a means for computer to receive external information and feed back the operation results to the outside world. For a standard personal computer, the main input devices are keyboard and mouse, while the output devices are monitors, printers and many other input and output devices that can be connected to the computer.
The control system connects all parts of the computer. Its function is to read instructions and data from memory and input/output devices, decode instructions, and pass the correct input that meets the requirements of instructions to ALU, telling ALU how to handle these data and where to return the resulting data.
An important part of the control system is a counter, which is used to record the address of the current instruction. Usually, the counter accumulates with the execution of the instruction, but sometimes if the instruction indicates a jump, the rule is not followed.
Refer to the above? Baidu Encyclopedia-Computer System?