1. The composition and working principle of the Von Neumann architecture computer system
Stored program + program execution
(1) All data and instructions should be expressed in binary form;
(2) All data and programs composed of instructions must be stored in the In the main memory, and then executed in a sequential manner, unless the display is modified;
(3) The hardware system of the computer should be composed of five basic components: memory, arithmetic unit, controller, input device, and output device. Under the unified control of the controller, the processing work described by the program is completed.
(4) One instruction can complete one operation. A computer can have many instructions, and the collection of all these instructions is called the computer's instruction set.
(5) The program is first loaded into the computer memory, and the CPU fetches an instruction from the memory, analyzes and recognizes the instruction, and finally executes the instruction, thus completing the execution cycle of an instruction. Then, the CPU fetches the next instruction in sequence, continues the next instruction execution cycle, and repeats until all instructions in the program are executed.
A computer system is composed of two parts: a hardware system and a software system . The hardware system consists of five basic components: memory, arithmetic unit, controller, input device, and output device. Software system: system software + application software.
The main functions and characteristics of each part of the hardware system:
①Memory: divided into main memory (internal memory) and auxiliary memory (external memory). The memory is a place for direct data exchange with the CPU, storing programs and data that are and will be running. Small storage capacity, fast access speed. The external memory stores a large amount of temporarily unused information and cannot directly exchange data with the CPU. The information on it must be loaded into the memory before it can be processed. The storage capacity is large and the access speed is slow.
② Calculator: Perform arithmetic and logic operations under the control of the controller, and send the results to registers or memory.
③Controller: Responsible for reading program instructions from the memory and analyzing them.
④ Input devices: Commonly used input devices include keyboards, mice, light pens, scanners, digitizers, etc.
⑤ Output device: Commonly used output devices include printers and monitors.
Main functions and characteristics of each part of the software system
① System software
Operating system: such as DOS, Windows, UNIX, OS/2, Linux, etc.
Database management system: such as FoxBASE, Oracle, etc.
Language compilation and interpretation system: Programming languages include C, FORTRAN, PASCAL, etc.
Network system: The network system is responsible for organizing and managing the network resources of the computer system, so that multiple independent computers can share resources and communicate with each other. communication.
② Application software
- Information management software: such as salary management software, personnel management software
- Text and form processing software: such as WPS, Word, Excel, etc.
- Graphics and image processing software: such as PhotoShop, Flash, etc.
- Auxiliary design software: such as CAD, CAM, CAI, CAT, etc.
- network communication software
2. Basic knowledge of programming languages
① Machine language: Each instruction in machine language is a binary code sequence composed of 0 and 1. Machine language is the lowest-level computer language for machine hardware. Programs written in machine language can be directly executed by computers without any translation and interpretation. Computers can only accept machine language expressed in binary form, so any non-machine language program must eventually be translated into a machine language program composed of binary code before the machine can execute these programs.
②Assembly language: A language that represents machine instruction code sequences in binary form with symbols (or mnemonics) is called assembly language. Assembly language is actually symbolic machine language. Although assembly language has made great progress in program writing, modification, and reading compared with machine language, and its operating efficiency is still high, it is still difficult to master due to the large number of machine instructions.
③High-level language: Both machine language and assembly language are machine-oriented languages, while high-level languages are problem-oriented languages. Programs written in high-level languages have better versatility and portability. High-level language source programs have two execution modes: compilation and interpretation. In the interpretation mode, the source program is interpreted and executed by the interpreter, and the target program is not generated. In the compilation mode, the source program must be compiled by the compiler to generate the corresponding The target program, and then generate an executable program through linking and assembly.
3. Computer virus-related knowledge
Definition of computer virus: Refers to a set of computer instructions or program codes that are compiled or inserted into computer programs to destroy computer functions or data, affect computer use, and are capable of self-replication.
A computer virus generally consists of three parts: the infectious part, the performance and destruction part, and the stimulating part. The
characteristics of computer viruses: concealment, latentness, infectivity, provocation, destructiveness, and mutation.
Detection of computer viruses: manual methods, automatic methods. The manual method uses the Debug debugging program and PCTOOLS tool software to perform manual detection and elimination. Automatic detection is to use special anti-virus software to automatically detect and eliminate viruses for one or more viruses.