What are the components of a computer system?

A computer system is composed of a hardware system and a software system; the hardware system is a collection of functional components that make up the computer system, including the central processor, internal memory, external memory and input and output devices, while the software system refers to A collection of various programs related to the operation of a computer system and any related documents and data, including system software and application software.

The operating environment of this tutorial: Windows 10 system, DELL G3 computer.

What is the composition of a computer system

The computer system is composed of two parts: a hardware system and a software system.

Computer hardware is a collection of functional components that make up a computer system. It is a general term for various computer components and equipment composed of electronic, mechanical and optoelectronic components. It is the material basis for computers to complete various tasks. Computer hardware is a physical entity that is visible and tangible.

Computer software refers to a collection of various programs related to the operation of a computer system and any related documents and data. A program is a sequence of statement instructions suitable for computer execution described in a programming language.

Computers without any software installed are often called "bare metal", and bare metal cannot work. If computer hardware is separated from computer software, then it becomes a useless machine. If computer software is separated from the computer hardware, it loses the material basis for its operation; therefore, the two are interdependent and indispensable, and together they constitute a complete computer system.

The basic composition of the computer system is as shown in the figure

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The basic composition and working principle of the computer hardware system

⑴ Computer hardware consists of five basic parts: arithmetic unit, controller, memory, input device and output device.

⑵ The computer uses binary to represent programs and data.

⑶ Using the "stored program" method, the program and data are placed in the same memory (internal memory), and the computer can automatically retrieve instructions from the memory for execution at high speed.

It can be said that each of the five major components of computer hardware has a relatively independent function and completes its own different work. As shown in Figure 1-7, the five major components actually work in a coordinated manner under the control of the controller. First, the program representing the calculation steps and the original data required in the calculation are sent to the computer's memory through the input device under the control of the controller input command. Secondly, when the calculation starts, the program instructions are sent to the controller one by one under the action of instruction fetching. The controller decodes the instruction and issues storage, fetch and operation commands to the memory and arithmetic unit according to the operation requirements of the instruction. The arithmetic unit calculates and stores the results in the memory. Under the action of the controller's fetching and output commands, the calculation results are output through the output device.

1. Operator (ALU)

The operator is also called the Arithmetic Logic Unit ALU (Arithmetic Logic Unit). Its function is to complete arithmetic operations and logical operations. Arithmetic operations refer to addition, subtraction, multiplication, division and their composite operations. Logical operations refer to logical comparison and logical judgment operations such as "and", "or" and "not". In a computer, any complex operation is converted into basic arithmetic and logical operations, and then completed in the arithmetic unit.

2. Controller (CU)

Controller CU (Controller Unit) is the command system of the computer. The controller generally consists of an instruction register, an instruction decoder, a sequential circuit and a control circuit. Its basic function is to fetch instructions from memory and execute instructions. An instruction is a one-step operation that instructs the computer how to work. It consists of two parts: the operation code (operation method) and the operand (operation object). The controller accesses the memory through the address, fetches the selected unit instructions one by one, analyzes the instructions, and acts on other components according to the control signals generated by the instructions to complete the work required by the instructions. The above-mentioned work starts over and over again, ensuring that the computer can work automatically and continuously.

The arithmetic unit and controller are usually collectively referred to as the central processing unit, that is, CPU (Central Processing Unit). It is the core component of the entire computer and the "brain" of the computer. It controls the computing, processing, input and output of the computer.

Integrated circuit technology is the basic technology for manufacturing CPUs for microcomputers, minicomputers, mainframes and supercomputers. Its development resulted in vast improvements in the speed and capabilities of computers. In 1965, Gordon Moore, founder of chip giant Intel, gave the famous Moore's Law: the number of transistors on a chip will double every 18 to 24 months. To everyone's surprise, this law very accurately predicted the 30-year development of chips. The first generation of integrated circuits in 1958 contained only two transistors, while in 1997, the Pentium II processor contained 7.5 million transistors. The Pentium 4 in 2000 had reached 0.13 micron technology and integrated 42 million transistors. The larger the number of transistors integrated into the CPU, the greater the computing power of the chip.

3. Memory

Memory is the memory device of the computer. Its main function is to store programs and data. Programs are the basis for computer operations, and data are the objects of computer operations.

⑴ Information storage unit

Programs and data are stored in the memory in binary form in the computer. The size of storage capacity is measured in bytes. Often expressed in KB (kilobytes), MB (megabytes), GB (gigabytes), and TB. The relationship between them is: 1KB=1024B=210B, 1MB=1024KB=220B, 1GB=1024MB=230B, 1TB=1024G=240B. In some calculations, 210 (1024) is often defaulted to 1000 for simplicity of calculation.

Bit (bit): It is the smallest unit for computer to store data. A single symbol "0" or "1" in a machine word is called a binary bit, which can store a binary number.

Byte (B for short): Byte is the measurement unit of computer storage capacity and the basic unit of data processing. 8 binary bits constitute a byte. One byte of storage space is called a storage unit.

Word (Word): When a computer processes data, the length of data accessed, processed and transmitted at one time is called a word. A word usually consists of several bytes.

Word Long: The length of data that the central processor can process simultaneously is the word length. The word length determines the data width of the CPU's registers and bus. The word lengths of modern computers are 8-bit, 16-bit, 32-bit, and 64-bit.

⑵ Classification of memory

According to the close relationship between memory and CPU, it can be divided into two categories: internal memory (main memory) and external memory (auxiliary memory). The memory is in the computer host. It directly exchanges information with the arithmetic unit and the controller. Although the capacity is small, the access speed is fast. Generally, it only stores running programs and data to be processed. In order to expand the capacity of the internal memory, external memory is introduced. As an extension and backup of the internal memory, external memory is indirectly connected to the CPU and is used to store some programs and data that the system must use but is not eager to use. The program must be transferred into the memory. can be executed. External storage has slow access speed, but has large storage capacity and can store large amounts of information for a long time.

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