Series Article Directory

        Chapter 1 Computer System Overview

        Chapter 2 Representation and Operation of Data

        Chapter 3 Storage System

        Chapter 4 Command System

        Chapter 5 CPU

        Chapter 6 Bus

        Chapter 7 Input/Output System

Table of contents

1.1 Development of hardware

1.2 Software Development

2. Hierarchical structure of computer system

2.1 The composition and structure of computer hardware

2.1.1 Early von Neumann structures

2.1.2 Modern computer architecture

2.2 Know the various components in the hardware structure

2.2.1 Main memory

2.2.2 Arithmetic Unit

2.2.3 Controller

2.3 The working process of the computer

2.4 Multilevel Hierarchy of Computer Systems

3. Computer performance indicators

1. The history of computer development

Computer system = hardware + software

1.1 Development of hardware

1.2 Software Development

The development of computer language has gone through machine-oriented machine language and assembly language , and problem-oriented high-level language . Among them, the development of high-level language has really promoted the development of software. It has experienced FORTRAN in scientific computing and engineering computing, PASCAL in structured programming, object-oriented C++ and Java adapted to the network environment.

At the same time, various system software that directly affects the performance improvement of computer systems have also made great progress, especially operating systems, such as Windows, UNIX, Linux, etc.

Computer software, generally divided into system software and application software

System software includes: operating system, database management system, language processing system (such as compiler), distributed software system, network software system, standard library system, service system (such as linker).
Application software includes: various scientific computing programs, engineering design programs, data statistics and processing programs.

Note: There is a difference between a database management system and a database system. A database management system is system software. The database system is generally composed of database, database management system, database administrator and application system. So it can only be said that there is system software in it, but it cannot be said that it is system software.

2. Hierarchical structure of computer system

2.1 The composition and structure of computer hardware

2.1.1 Early von Neumann structures

The American-Hungarian scientist von Neumann first proposed the idea of "stored program" and successfully applied it to the design of computers. The computers manufactured according to this principle are called von Neumann structure computers. Because of his outstanding contributions to modern computer technology, von Neumann is also known as the "father of modern computers".

The concept of "stored program" refers to inputting instructions into the main memory of the computer in the form of binary code in advance , and then executing the first instruction of the program according to its first address in the memory, and then executing other instructions in the order specified by the program , until the end of program execution. That is, access and execute instructions sequentially by address

Von Neumann architecture has the following characteristics:

The computer hardware system consists of five major components (memory, arithmetic unit, controller, output device, input device)
Instructions and data are stored in the memory at the same position and can be accessed by address
Instructions and data are represented in binary
Instructions consist of opcodes and address codes
stored program
Calculator - centric

In computer systems, software and hardware are logically equivalent. (That is, for the same function, we can use software or hardware to realize it, but the cost of software implementation is lower and the efficiency is lower, hardware is the opposite. For example: for multiplication, you can Design a special hardware circuit to realize it, or use software to perform multiple addition operations.)

2.1.2 Modern computer architecture

In the early von Neumann architecture centered on the arithmetic unit, when the input and output devices input and output data, they all need to go through the relay of the arithmetic unit, and the arithmetic unit itself needs to perform calculation operations, which will reduce the The efficiency of computers, so modern computers have improved for this.

Modern computers are memory -centric.

2.2 Know the various components in the hardware structure

2.2.1 Main memory

Storage can be divided into:

Main memory: also known as internal memory, which can be directly accessed by the CPU
Auxiliary memory: Also known as external memory, it assists the main memory to store more information. The information in the auxiliary memory needs to be imported into the main memory before it can be accessed by the CPU.

The main memory can be divided into the following three parts:

Address register (MAR): access memory address, find the selected storage unit after address decoding
Data Register (MDR): An intermediary between memory and other components, used to temporarily store information to be read or written from memory
storage: store data

2.2.2 Arithmetic Unit

2.2.3 Controller

In addition to the above three important components, there are the following two devices:

Input device refers to the input of external information in a way that the computer can understand, such as keyboard, mouse, etc.

The output device is to output the information processed by the computer in a form acceptable to humans, such as a display screen and a printer.

Generally, the arithmetic unit and the controller are integrated on the same chip, which is called the central processing unit (CPU) . The CPU and the main memory together constitute the host , and other hardware devices (external memory, I/O devices, etc.) except the host are collectively called external devices, or peripherals for short.