Overview
The concept, characteristics and development history of
computer The hardware and software parts of the computer
Different types of hardware and software and their classification The function of each component of
computer hardware The
different types of computer memory
Computer network and its classification
Computer network topology
computer and its application
- scientific research and scientific computing
- Information transfer and information processing
- Automation of production processes and management automation
- Computer Aided Design and Aided Manufacturing
- computer aided education
- entertainment
- ……
computer history
development time
| era | Salient features |
|---|---|
| Pioneers in the age of mechanical computers | Basically, it is a mechanical operation method without entering the computer soul - logical operation. |
| The first days of electronic computers | Transition from mechanical to electronic. There is no software system and can only be programmed in machine language and assembly language. |
| The development of transistor computers | The invention of the transistor was the starting point for the computer to take off. With system software and high-level languages. |
| Integrated circuits, modern computers with soaring wings | Integrated circuits are small in size. It runs fast. Failures are reduced. Time-sharing operating system. Structured Programming Ideas |
| computer technology into brilliance | After INTEL released the microprocessor 8080 for personal computers, Steve Jobs, Bill Gates and other trendsetters appeared. The unprecedented development of Internet technology and multimedia technology. |
Function
components of a computer system
software
According to the function of the software
1) System software The
operating system is the most typical core system software, which is the bridge of human-computer interaction.
The most popular system software at present are DOS, Windows, Linux, Unix, Mac, etc.
2) Application software
Application software is software that depreciates in order to solve various computer applications. For example, Microsoft Office
application software needs the support of system software, and system software is the application software. Supporting environment for software development and operation
By software size
| Types of | Number of developers | Development time | source code lines |
|---|---|---|---|
| miniature | 1 | 1-4 weeks | 500 lines |
| small | 1 | January-June | 1000-2000 lines |
| medium | 2-5 | 1-2 years | 5000-50000 lines |
| large | 5-20 | 2-3 years | 50000-500000 lines |
| very large | 100-1000 | 4-5 years | 1000000 lines |
| very large | 2000-5000 | 5-10 years | 10000000 lines |
hardware
CPU
It performs the operation and processing functions of the computer, and it also controls other parts of the computer. The central processing unit determines the performance of the entire computer system.
external device
1) Input Devices
Keyboard , Mouse, Scanner
2) Output Devices
Monitors and Graphics Cards, Printers, Speakers and Sound Cards
memory
1) Internal memory
Read only memory (ROM), from which information can only be read, but not written. When power off or crash, the information can still be retained.
Random Access Memory (RAM), when the computer is running, system programs, application programs and user data are temporarily stored in RAM. System programs will be loaded into it when it is turned on, and its information will disappear when it is turned off or powered off.
2) External storage
floppy disks and floppy disk drives
Hard disks and hard disk drives
CD-ROM and CD - ROM drives
USB
removable devices for 1B. 1024B is 1KB. 1024KB is 1MB. 1024MB is 1GB. 1024GB is 1TB. Note: When we express data storage, b means byte, and b means bit during network transmission or data transmission. So the broadband 1Mb refers to 1M bit, that is, 0.125M byte.
The working relationship between external memory, internal memory, and CPU
The internet
The composition of a computer network
computer network topology
1) Bus type Only one pair of nodes is allowed to occupy the bus communication
at the same time. The bus topology is simple, easy to implement, and easy to expand, but it is difficult to detect faults.
2) Star-shaped
Each node is connected to the central node and arranged in a radial shape around the central node. The failure of a single node will not affect the rest of the network, but the failure of a central node can lead to the paralysis of the entire network.
3) Ring type
The ring type topology has good anti-failure performance, but the failure of any node or a transmission medium in the network will lead to the failure of the entire network.
In actual large-scale networks, all three structures are mixed together to form a hybrid topology network structure to make up for mutual defects. Small LANs use a star network topology.
Classification of computer networks
| network name | coverage | main feature |
|---|---|---|
| Local Area Network (LAN) | Small coverage: a few meters to 10 kilometers | High speed, reliability, low investment, narrow connection range, less users, easy configuration. |
| Metropolitan Area Network (MAN) | In a city, the interconnection of computers not within the confines of a consenting geographic cell. 10-100 km | In a large city, a MAN is usually connected to multiple LANs through the city's communication lines. |
| Wide Area Network (WAN) | Generally, it is connected by LAN or MAN network between different cities. Geographical range from several hundred kilometers to several thousand kilometers. | The longer the distance is, the more serious the information attenuation is. Connected by long-distance communication lines, microwaves, satellites, etc. The speed is low, it is easy to fail, and the investment is large. |
| Internet | The network extends to most of the globe and is the largest computer network in the world. | A large amount of information and wide dissemination. |
Note:
It should be noted that the division of the network is not strictly a geographical division, but a qualitative concept. The most used in life is the local area network, because it can be large or small, it is easier to implement whether it is a family or a unit, and it is also the most widely used network.
Summarize
computer history
Computer development has experienced five development eras from the mechanical computer era, the tube computer era, the transistor computer era, the integrated circuit computer era, to the VLSI computer era.
computer system components
A computer consists of software and hardware. Software is divided into system software and application software. Hardware includes host and peripherals. Hardware specific components: central processing unit, memory, input and output devices. The various parts include motherboard, CPU, hard disk, graphics card, memory, sound card, floppy drive, monitor, mouse, keyboard, modem, etc.
computer network
A computer network is a system in which computer systems in different geographical locations are connected through communication equipment and lines to realize shared resource sharing with network software.
A computer network consists of hardware systems and software systems. Network hardware includes computers, network equipment and communication lines. The connection form and method of these three types of hardware are called network topology. The main network topologies include bus, star and ring.
According to the geographical scope, the network can be divided into four types: local area network, metropolitan area network, wide area network and the Internet.
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