Development
A machine system that receives and stores information according to human requirements, automatically processes and calculates data, and outputs result information. General-purpose computer General-purpose computer is an extension and expansion of brain power, and is one of the major achievements of modern science.
General-purpose computer systems are composed of hardware (sub)systems and software (sub)systems. The former is an organic combination of various physical components based on the principles of electricity, magnetism, light, and machinery, and is the entity on which the system works. The latter are various procedures and documents used to direct the entire system to work according to specified requirements.
Since the first electronic general-purpose computer came out in 1946, general-purpose computer technology has made amazing progress in components, hardware system structures, software systems, and applications. Modern general-purpose computer systems range from micro general-purpose computers and personal general-purpose computers to giant general-purpose computers and their networks. They have various forms and characteristics. They have been widely used in scientific computing, transaction processing, and process control, and have become increasingly popular in various fields of society. The progress of society has a profound impact.
Electronic general-purpose computers are divided into two categories: digital and analog. Generally speaking, general-purpose computers refer to digital general-purpose computers, and the data processed by their operations are represented by discrete digital quantities. The data processed by analog general-purpose computer operations are represented by continuous analog quantities. Compared with digital machines, analog machines are fast, have simple interfaces with physical devices, but have low accuracy, difficult to use, poor stability and reliability, and expensive. Therefore, the simulator has become obsolete, and it is only used in occasions that require fast response but low accuracy. The hybrid general-purpose computer that combines the advantages of the two ingeniously still has a certain vitality.
Features
The general computer system is characterized by accurate and fast calculation and judgment, and the general-purpose computer is good, easy to use, and can be connected to a network. ①Calculation: Almost all complex calculations can be realized by arithmetic and logical operations with general-purpose computers. ②Judgment: General-purpose computer has the ability to distinguish different situations and choose different processing, so it can be used in management, control, confrontation, decision-making, reasoning and other fields. ③Storage: General-purpose computers can store huge amounts of information. ④Accurate: As long as the word length is sufficient, the calculation accuracy is theoretically unlimited. ⑤Fast: The time required for one operation of a general-purpose computer is as small as nanoseconds. ⑥General-purpose computer: General-purpose computer is programmable, and different programs can realize different applications. ⑦Easy to use: Abundant high-performance software and intelligent man-machine interface greatly facilitate the use. ⑧Networking: Multiple general-purpose computer systems can transcend geographic boundaries and share remote information and software resources with the help of communication networks.
Classification
Computer systems can be classified according to system functions, performance or architecture. ① Special purpose and general purpose computers: Early computers were designed for specific purposes and were of special nature. Since the 1960s, it has begun to manufacture general-purpose computers that take into account the three applications of scientific computing, transaction processing and process control. Especially the emergence of serial machines, the adoption of various high-level programming languages of standard texts, and the maturity of the operating system enable a model series to choose different software and hardware configurations to meet the different needs of users in various industries, and further strengthen Versatility. But special purpose machines are still being developed, such as all-digital simulators for continuous dynamics systems, ultra-mini space special computers, and so on.
② Supercomputers, mainframes, medium-sized computers, minicomputers, and microcomputers: Computers are developed based on large and medium-sized computers as the main line. Minicomputers appeared in the late 1960s, and microcomputers appeared in the early 1970s. They are widely used because of their light weight, low price, strong functions, and high reliability. In the 1970s, supercomputers capable of computing more than 50 million times per second began to appear, and they were specially used to solve major issues in science and technology, national defense, and economic development. Giant, large, medium, small, and microcomputers, as the echelon components of computer systems, have their own uses, and they are all developing rapidly.
③ Pipeline processor and parallel processor: Under the condition of limited speed of components and devices, starting from the system structure and organization to achieve high-speed processing capabilities, these two processors have been successfully developed. They all face ɑiθbi=ci(i=1, 2, 3,...,< i>n; θ is an operator) such a set of data (also called vector) operations. The pipeline processor is a single instruction data stream (SISD). They use the principle of overlap to process the elements of the vector in a pipeline manner, and have a high processing rate. Parallel processor is a single instruction stream multiple data stream (SIMD), which uses the principle of parallelism to repeatedly set up multiple processing components, and simultaneously process the elements of the vector in parallel to obtain high speed (see Parallel Processing Computer System). Pipeline and parallel technology can also be combined, such as repeatedly setting multiple pipeline components to work in parallel to obtain higher performance. Research on parallel algorithms is the key to the efficiency of such processors. Correspondingly expand vector statements in high-level programming languages, which can effectively organize vector operations; or set up vector recognizers to automatically recognize vector components in source programs.
An ordinary host (scalar machine) is equipped with an array processor (only for high-speed vector operation pipeline dedicated machine) to form the main and auxiliary machine system, which can greatly improve the processing capacity of the system, and the performance and price The ratio is high, and the application is quite wide.
④ Multiprocessors and multicomputer systems, distributed processing systems and computer networks: Multiprocessors and multicomputer systems are the only way to further develop parallel technology, and are the main development directions for giant and mainframes. They are multiple instruction streams and multiple data streams (MIMD) systems. Each machine processes its own instruction stream (process), communicates with each other, and jointly solves large-scale problems. They have a higher level of parallelism than parallel processors, with great potential and flexibility. Using a large number of cheap microcomputers to form a system through the interconnection network to obtain high performance is a direction of research on multiprocessors and multicomputer systems. Multiprocessors and multicomputer systems require the study of parallel algorithms at a higher level (processes). High-level programming languages provide means for concurrent and synchronizing processes. The operating system is also very complex, and it is necessary to solve the communication and synchronization of multiple processes between multiple computers. , Control and other issues.
Distributed system is the development of multi-computer system. It is a system that is physically distributed by multiple independent and interacting single computers that cooperate to solve user problems. Its system software is more complex (see distributed computer System).
Modern mainframes are almost all multi-computer systems with distributed functions. In addition to containing high-speed central processing units, there are input and output processors (or front-end user computers) that manage input and output, manage remote terminals, and network communications. The communication control processor, the maintenance and diagnosis machine for system-wide maintenance and diagnosis, and the database processor for database management. This is a low-level form of the distributed system.
Multiple geographically distributed computer systems are connected to each other through communication lines and network protocols to form a computer network. It is divided into a local (local) computer network and a remote computer network according to the geographical distance. Each computer on the network can share information resources, software and hardware resources with each other. Ticket booking systems and information retrieval systems are examples of computer network applications.
⑤ Neumann machine and non-Neumann machine: The Neumann machine driven by stored programs and instructions still dominates so far. It executes instructions sequentially, which limits the parallelism inherent in the problem to be solved and affects the further improvement of processing speed. The non-Neumann machine that breaks through this principle is to develop parallelism from the architecture and improve system throughput. Research work in this area is ongoing. Data flow computers driven by data flow and highly parallel computers driven by reduction control and on demand are all promising non-Neumann computer systems.