2.2 Computer Architecture
Before this lesson, I always thought a computer system architecture is composed of a variety of hardware of a computer, computer system architecture results could be so complicated.
User layer sixth floor: an executable program
High-level language virtual machine layer fifth layer: C, C ++, Java, etc.
Assembly language layer of the fourth layer: the assembly language code
Operating system and third layers: the operating system, library code
************************************** software and hardware interface
A second layer of machine language: instruction set architecture
Control physical layer of the first layer: micro-program or hardwired
Digital circuit layer zeroth layer: a gate circuit, the electronic circuit
I thought that computer science is to knock code, now more able to appreciate the need for a systematic study of the profession, its coverage is really wide. Now learning digital logic zero is the content of the layer, and we are also learning C ++, Java, after feeling through college these seven should be understand.
But I still prefer to learn in five-six.
2.3 Mobile Terminal
Modern mobile terminal performance is getting better, the market is also high.
2.4 Computer Network
Category :
LAN, MAN, WAN
Wireless network, a wired network
LAN such as campus networks, metropolitan area has a hometown feel i-guangping seems to be the network, wide area network no contact, as if to cover the continent, it may be involved over the wall or something.
Wireless To say wifi, cable networks such as cable pull.
Computer network hardware component :
1, network transmission media: twisted pair, coaxial cable, fiber optic, infrared, microwave
Among the most common twisted pair, now finally I know what he called. Optical fiber transmission network can quickly take advantage of total reflection, I thought it would end, but the street selling small toys also have fiber.
2, repeater
Resend or forward to expand the network transmission distance.
Small not seen, but also seen the big iron shelves repeater.
3, the hub
This thing seen in the school room can be shared broadband.
4, switch
The number of machines connected together to form a local area network.
5, router
Is a network of connected devices, is the hub of the Internet.
Now the family are using this.
Network topology :
1, bus:
Easy to use, the most widely used.
2, Star:
Single point nothing bad, bad center all bad.
3, ring:
A loss for both sides.
4, tree:
A strong dependence of the root node.
Computer Network Architecture :
OSI reference model:
Host A Host B
Application layer The application layer protocol
It represents a presentation layer protocol layer denotes
Session layer session layer protocol session layer
Layer protocol transport layer, the transport layer
Network Layer Network Layer Protocol Network Layer
Data link layer data link layer protocol data link layer
PHY physical layer transmission medium
TCP / IP reference model:
Layer 5: The session layer, presentation layer application layer composition into the application layer.
Layer 4: then the data link layer to the physical layer network interface layer composition.
Computer network protocols :
HTTP: Internet access in web resources
FTP: FTP white prostitute can go to school resources
DNS: Each domain name corresponds to an IP, IP is not necessarily a domain name.
2.5 cloud and Things
Cloud computing :
The company will idle resources used to earn money, to provide users with high-performance computer cluster, the user need not consider replacing the computer
Generation problem, sounds good.
Service mode:
SaaS software as a service
PaaS Platform as a Service
IaaS Infrastructure as a Service
Deployment models:
Public cloud: there are security risks
Private cloud: large investment
Community cloud: the personal use of private cloud and more
Hybrid Cloud
Things :
Let objects speak, have a great convenience of human life
Features:
Overall perception; rich sensor
Reliable delivery
Intelligent Processing