table of Contents
A programming language
1. What is the programming language
Programming language is the medium of communication between man and computer.
2. What is programming
A pile of documents written in a programming language
3. Why Programming
Program aims to help people accomplish certain specific things, instead of labor
4. What are the different programming languages
(1) a total of three categories: == machine language, assembly language, high-level language ==
Machine language : a full string of numbers consisting of 0 and 1, the machine can be directly identified.
Pros: the efficiency is very high. Cons: Very difficult to develop
Assembly language : encapsulation algorithm by a number of keywords, such as add (a, b), represents a + b.
(Advantages and disadvantages compared to the machine language) Advantages: high development efficiency. Disadvantages: low efficiency
High-level language : high-level language into two categories: compiled languages and interpreted languages
Compiled language : is now the code line by line. Google Translate translation similar way, one-time translation of all the code finished, then run. Such as: C / C ++ / Java / Go
(Compared to interpreted languages advantages and disadvantages) advantages: high efficiency. Disadvantages: low development efficiency (difficult to find BUG)
Interpreted languages : Today is the code line by line. Simultaneous translation is similar to the way that writing a translation sentence. Such as: Python / JavaSript / PH / R
(Compared to compiled languages pros and cons) Pros: high development efficiency. Disadvantages: low efficiency (translator written by a compiler language)
Second, computer components
1. Von Neumann machine composed of five
(1) controller, a computing unit, a memory, input devices, output devices
Corresponding hardware:
== CUP == (including a controller and operator)
== == main memory (i.e., memory): fast but small capacity, power disappears;
== == external memory (HDD): capacity, but slower.
Mechanical hard disk: a robotic arm, track and sector components.
Robot: read data
- Average seek time (mechanical arm to lift or put down == == time):
Since the technological level of restrictions is 5ms.
Average delay time (the robot arm on the track half turn == == draw time):
As a 7200r / min hard
7200/60=120r/s 1/120=0.0083s/r=8.3ms 8.3/2=4.15ms
The average time to find data: 5 + 4.15 = 9.15ms
Track: storing data
Sector
== == mouse, keyboard, etc.
== display and printer ==
(2) multi-core CPU: can do more things at a time, please.
(3) 32-bit and 64-bit operating systems: binary number read-time (i.e., 0 and 1), backward compatible (i.e., 64-bit operating system may use 32-bit software).
2. Operating System
(1) With the computer's operating system is divided into three major components:
- Applications (software): interact with the operating system
- Operating system (software): interact with applications and hardware
- Hardware:, direct interaction with the hardware and operating system interaction
(2) What is the use operating system
Operating system provides us with one interface to simplify operation of complex hardware
(3) file
What is the application procedure
Applications that piles of documents
What is the file
File is a virtual operating system to provide you with the unit, used to store information
Start (4) of the application
Application startup process:
Such as QQ:
- QQ Double-click the desktop icon (the icon by the operating system, stored QQ path), the operating system notifies CUP (QQ find the location on your hard drive) - "
- CUP Let QQ memory to external memory read data, the data into the memory - "
- Start QQ
(5) operating system boot
- Boot process:
- Boot, boot the operating system temporary == (stored in the ROM memory, ROM memory in the factory when it was written dead, the content can not be changed) == - "
- Temporary operating system to invoke the Z == CMOS temporary memory (temporary memory battery powered CMOS, which stores the real operating system path, when reloading system, modified boot disk is modified in this position) == true in operating system path on your hard disk - "
- Start the real operating system, the operating system is shut down temporarily
Third, the network bottleneck effect
The reason: Since the time of the network communication is far greater than the execution time of the program - "More needs to network-based programs -" interpreted language more fire