As a student majoring in communication , Recently, professional teachers are talking about the principle of single chip microcomputer , It is similar to the computer composition principle of computer specialty , therefore , A brief understanding of the principle of computer composition ( Through Harbin Institute of Technology -- Liu Hongwei's online class ), And share their learning content .

Divide the computer from the perspective of software and hardware :

  Understanding computer from the perspective of physical composition (9 layer ):

The first 1 layer :Physics( physical layer )

The first 2 layer :Devices( Device layer )

The first 3 layer :Analog Circuits( Analog circuit layer )

The first 4 layer :Digital Circuits( Digital circuit layer )

The first 5 layer :Logic( Logical layer )

The first 6 layer :Micro-architecture( Microstructure layer )

The first 7 layer :Architecture( Architecture ): Group logical components together to implement instructions defined in the architecture .

The first 8 layer :Operating Systems( operating system )

The first 9 layer :Application Software( Application software )

Hierarchy of computer system

  Modern computer hardware block diagram

  Six characteristics of von Neumann system  

Von Neumann Architecture : Computer storage mechanism computer , Numbers and programs are stored in the computer in binary form .

1) The computer consists of five parts : Arithmetic unit , controller , storage , Input and output devices .

2) Instructions and data are stored in memory in the same status , Accessible by address .

3) Instructions and data are represented in binary

4) Instructions consist of opcodes and address codes

5) Stored program

6) Center on arithmetic unit

Main technical indexes of computer hardware

1) Machine word length :CPU Number of bits that can process data at one time ( And CPU Related to the number of register bits ).

2) Operation speed

3) storage capacity ( Total number of bits for storing binary information )

A. Main memory capacity ( Memory )

B. Auxiliary storage capacity  ( External storage : Hard disk ,U disc , CD, etc )

CPU Structure and function of

1) controller

2) Arithmetic unit

Realize arithmetic operation and logic operation

Understanding of computer storage devices

1) Storage pyramid

2) cache

Why cache ?

CPU There is a difference between the speed of and main memory ; stay CPU Process a lot of data at the same time , And can not transmit all data at the same time , Temporarily put the data with low priority into the cache , Wait until the high priority data is processed, and then take them out of the cache for processing , Instead of accessing slower memory , of course , If necessary, the data is in the Cache Not in ,CPU Will read the data in memory again ; Avoided CPU" Wait " Phenomenon of .

  Cache improvements : Increase the level of cache

3) Main memory ( Memory )

Main memory is memory ; Is directly related to CPU Memory for exchanging information , finger CPU Memory that can be accessed directly through the address code in the instruction ,

1)ROM

Read only memory , It is a kind of solid-state semiconductor memory that can read and realize the stored data ;ROM The stored data is stable , The stored data will not change after power failure . Important characteristics : After one-time write , Can only read , Can no longer write .

about ROM Say , Is it a hard disk ? Not that ROM Can I only read ? It must be clear ,RAM and ROM It's all memory , The hard disk is external memory , therefore ROM Not equal to hard disk .

2)RAM

Random access memory , Is with CPU Internal memory for direct exchange of data ; In case of power failure, the stored contents of the device will be lost , Therefore, it is mainly used to store programs used for a short time . It can read and write at any time , And fast , It is usually used as a temporary data storage medium for the operating system or other running programs .
RAM and ROM comparison , The biggest difference between the two is RAM After power failure, the data saved on it will disappear automatically , and ROM It won't disappear automatically , It can be stored without power for a long time . Important characteristics : You can read and write at any time , Fast speed .

3)ROM,RAM Compare with hard disk

ROM Read only memory , Relative RAM Random access memory , They are all memory . And hard disk (HDD) It is a kind of external memory . They are not a concept at all .

There are two major differences between memory and external memory :

one , Memory needs power to store data , In case of power failure, it will cause data loss , External storage does not need power supply ;

two , The reading and writing speed of memory is much higher than that of external memory .ROM It is called read only memory , Because it is impossible to write or modify data through general methods , Can only read ; and RAM Random access can be realized .

4) Supplementary deposit  ( External storage )

characteristic : Not directly with CPU Exchange information

5) Speed comparison

CPU > cache (Cache) > Main memory > Supplementary deposit

4) summary

CPU Don't deal with peripherals , Dealing directly with memory

Peripheral discord CPU Deal with , Dealing directly with memory

Memory is the core of computer data .

But we found that the controller can communicate with peripherals directly , Dealing with memory .

Von Neumann Architecture , It depends on the hardware , Peripheral data must be stored in memory first CPU,CPU Data must pass through memory and then to peripherals . Lay the foundation for the development of computer in the future . The operating system is mounted on the computing computer hardware through this property .
 

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