Main contents:
Computer design ideas (stored program and program control)
Computer hardware composition
The hierarchy of computers (computers in different people's eyes)
The working process of the computer
First, what is a computer?
Different from ordinary electronic equipment, computer is a complex automation equipment composed of hardware and software, and it is an electronic equipment that can automatically, quickly and accurately process, process and store information.
The biggest difference between computers and general electronic equipment is not only hardware, but also software.
Second, the classification of computers.
Computers are generally divided into:
analog computer
Digital computer (computer)
Computers are divided into:
Special machine
universal machine
Digital computers are further divided into:
Mainframe, mainframe, medium-sized computer, minicomputer, microcomputer, single chip microcomputer.
The main differences are volume, power consumption, performance index, storage capacity, instruction system and machine price.
Differences between different digital computers
Third, the application of computers.
Scientific computing
automation
Measurement and testing
information handling
Education and health
home appliances
artificial intelligence
Fourth, computer design ideas
The computer is so magical, so how does it work and how is it made?
The first electronic digital computer in the world is ENIAC, which was born in the University of Pennsylvania on February 5, 1946.
The world's first computer ENIAC
Features of ENIAC:
Adopt decimal system
20 accumulators, 10 bit
Manual programming with switch
18000 test tubes
Weighing 30 tons
Covering area170m2.
The power consumption is 140 KW.
5000 times/second addition operation
Today, ENIAC is not perfect, but its birth is a milestone.
Von Neumann computer
While developing ENIAC, the research team headed by Hungarian mathematician von Neumann put forward the computer design idea of "stored program, program control", and the computer EDVAC, which embodies this design idea, came out in 195 1 year.
Von Neumann's concept of stored program control can be summarized as follows:
Computer hardware should consist of five basic components: arithmetic unit, controller, memory, input device and output device.
Computers use binary to represent instructions and data.
The most important thing is to store the programmed program and original data in memory in advance, and then start the computer work.
At present, most computers are still based on the concepts of stored programs and program control, and are called von Neumann computers.
Fifth, the digital representation of information.
Digital codes can represent information.
Representing digital data with digital codes
Indicate instructions with numerical codes.
Represent an image with a digital code
A digital signal may represent a digital code.
Level: high means 1, and low means 0.
Pulse: Yes means 1, and No means 0.
-Information can be represented by numbers, and can be represented by 1, 0.
Six, the working mode of the stored program
Program in advance according to problem solving.
Store the program in the computer.
Start the computer automatic execution program
-It embodies the process of solving problems with computers.
Seven, computer hardware composition
Storage; stock
potato
controller
main storage
input device
Output device
auxiliary memory
cpu
control
data
Address/Description
host machine
ancillary equipment
1, operator
The function of arithmetic unit is to perform arithmetic operation, logical operation and data conversion.
Usually, binary numbers are used for operations, and 1 and 0 can be expressed by the voltage and the presence or absence of pulses.
The operation rules of binary numbers are simple, easy to realize in electronic circuits and high in reliability.
2. Controller
The function of the controller is to coordinate the automatic work of computer components. Specifically, the steps (instructions) to solve the problem are taken from the memory, analyzed, and then some operations are performed.
The function of instruction is to tell the controller what to do, where the data comes from and where the result goes. This manual consists of two parts:
Instructions are represented in binary and stored in memory in advance, which is called a stored program.
The controller controls the computer to complete the calculation task according to the stored program, which is called program control.
Stored program and program control are important design ideas of von Neumann computer.
operation code
Address code
3. Memory
The function of memory is to store programs and data.
The memory is composed of semiconductor devices. A flip-flop represents 1 bit binary, and 16 bits need 16 flip-flops.
All flip-flops that hold a number are collectively referred to as a storage unit. Each unit has a number called an address.
The total number of all storage units in a memory is called storage capacity, which is generally expressed in KB, MB and GB. The larger the storage capacity, the more information you can remember.
4. Input devices
The task of the input device is to send the compiled program and original data to the computer and convert them into information forms that the computer can recognize and accept.
There are many kinds of input devices, such as mouse, keyboard and scanner.
5. Output devices
The task of the output device is to send the processing results of the computer out of the computer in a form acceptable to people or other devices.
There are many kinds of output devices, such as monitors and printers.
CPU, host, peripherals
Central processing unit CPU:
CPU = Arithmetic Unit+Controller
Computer host:
Host = CPU+ main memory
External equipment:
Hardware devices other than the host computer
Eight, computer bus structure
Bus is a common channel for information transmission shared by multiple functional components in time sharing, and it is an interconnection mechanism that constitutes a computer system.
Characteristics of bus: time sharing, * * * *
A single bus is a bus structure, which is not a signal line, but includes an address bus, a data bus and a control bus.
system bus
Engagement/interface
Engagement/interface
ancillary equipment
ancillary equipment
…
cpu
main storage
Nine, computer software
Software is divided into two categories:
system software
Application software.
System software is divided into four categories:
service program
Language program
operating system
Database Management System (DBMS)
Examples of application software:
Engineering design program
Data processing program
Automatic control program
Enterprise management plan
Information retrieval program
Scientific calculation program, etc.
software development
machine language
assembler language
algorithmic language
operating system
Database Management System (DBMS)
assembly program
What is this,
I'll translate
Interpreter/compiler
Nothing, I
Let's explain/translate
100 10 1 1 10
00 1 100 10 1
1 10000 1 10
……
X. Hierarchical structure of computer system
A computer can't be simply regarded as an electronic device, it is a very complicated whole composed of hardware and software.
In front of different observers, computers are not exactly the same electronic devices.
Computers observed by ordinary users
Computer observed by professional users
A computer observed by a computer designer.
Hierarchical structure of computer
Computers are generally considered to be composed of six different levels:
Grade?Six
Applied language level
Fifth floor
Advanced language level
The fourth stage
Assembly language level
The third stage
Operating system level
assistant
General machine level
first step
Microprogram level
Specially designed to meet a certain purpose, its language is various problem-oriented application languages. Users see intelligent machines that can solve some special problems.
High-level language level is set to facilitate users to write applications, supported by various high-level language compilers and oriented to programmers.
A symbolic language-assembly language is provided to reduce the complexity of programming, which is translated into machine language by assembler, and this level is supported by assembler.
It is realized by operating system, which directly manages the software and hardware resources of traditional machines and is an extension of traditional machines. At the same time, the tasks of the whole system should be scheduled.
Machine language is the instruction set of a machine, and machine language programs can be interpreted by microprograms, that is, microprograms interpret the machine instruction system. This layer is the interface between software and hardware.
Microprograms written by microinstructions are directly executed by hardware. Microprograms are solidified in ROM, which is often called "firmware". The second level is for machine designers.
virtual computer
Physical machine
Logical equivalence between software and hardware
Hardware is the foundation of computer system, and software is the flexibility of computer system.
Any operation can be realized by hardware and software; The execution of any instruction can be accomplished by software or hardware. This is the logical equivalence between software and hardware.
The boundary between the first level and the second level is expanding to the third level or even higher. Software often solidifies, and the solidified program is called firmware.
The process of executing a program by a computer
Put the programmed program in the main memory, and take out the instructions one by one under the control of the controller for execution. Take the arithmetic unit with single accumulation register structure as an example to calculate a+b-c=
Computer technical index
Machine word length: the number of bits of binary information that can be directly processed. Word length indicates accuracy, and the longer the word length, the higher the accuracy.
Main frequency: the clock frequency of CPU. Generally speaking, the higher the clock frequency, the faster the running speed.
Bus width: the number of bits that the data bus can transmit information in parallel at a time. Generally refers to the width of the external data bus.
Storage capacity: the total number of binary words that the system can store, in KB, MB, GB, TB, PB.
Operation speed: how many instructions can be executed per second, in millions of instructions per second.
XI。 The past and future of computers
The first electronic digital computer in the world is ENIAC, which was born in the University of Pennsylvania on February 5, 1946. From today's point of view, this computer consumes a lot of power and is not perfect, but it is an epoch-making innovation in the history of science and laid the foundation for electronic computers. Since its advent, computers have gone through five stages of change.
The past of computers
First generation: electron tube computer from 1946.
The second generation: transistor computer from 1958.
The third generation: small and medium-sized integrated circuit computers since 1965.
The fourth generation: 197 1 started large-scale and very large-scale integrated circuit computers.
The fifth generation: 1986 VLSI computer.
Since the computer was born in 1946, its computing speed has increased by 10 times, its reliability has increased by 10 times, its cost has decreased by 10 times and its volume has decreased by 10 times every five years. The development of computer in the past 60 years is based on the structure of von Neumann computer, focusing on how to improve the speed.
The future of computers
Microcomputer will develop in the direction of miniaturization, networking, high performance and multi-purpose.
Supercomputers are developing in the direction of being more giant, ultra-high-speed, parallel processing and intelligent.
Entering the communication-centric architecture, the computer is the network.