Shulou(Shulou.com)06/03 Report--

I. the development history of operating system and multi-channel technology

1. First generation computers (1940-1955): vacuum tubes and punched cards

Features: there is no concept of operating system, all programs are designed to directly control the hardware.

Advantages: everyone has their own, you can debug your own code and find bug.

Disadvantages: waste of computer resources.

two。 Second generation computer (1955-1965): transistors and batch processing systems

Features: praise all the code together, let a CPU share, but still run one by one, or sequential algorithm (serial)

Advantages: batch processing, saving machine time.

Disadvantages: there are people involved, the trouble of moving in and out, slowing down the speed of the program.

3. The third Generation computer (1965-1980): integrated circuit chips and multiprogramming

The operating system of the third generation computer widely uses the key technology that the second generation computer operating system does not have: multichannel technology.

Multichannel technology: (refers to multichannel / program)

1. Spatial reuse: memory should support running into multiple programs at the same time

two。 Time reuse: multiple programs need to be able to switch (when to cut? A program takes too long to cut; when CPU encounters IO blocking, the waiting time should be cut)

4. The fourth Generation computer (1980 ~ present): personal computer

Second, why use the operating system?

Programmers can not understand all the details of hardware operation. It is a very tedious work to manage these hardware and optimize them. This tedious work is done by the operating system. With him, programmers are freed from these tedious work. They only need to consider the writing of their own application software, which directly uses the functions provided by the operating system to use the hardware indirectly.

Third, the two major functions of the operating system

1. Provide applications with an abstraction of how to use hardware resources

two。 Order the competition of multiple programs for hardware (management applications)

IV. Classification of computer languages

Machine language:

Features: write programs with zeros and ones that the computer can understand

Advantages: the program runs fast.

Disadvantages: low development efficiency

Assembly language:

Features: use some English tags instead of a string of binary numbers to write programs

Advantages: a little better than machine language, a large number of assembly languages are used in the operating system (the operating system does not need a network, the speed is getting better and better)

For example, the calling code about the process is written in assembly language.

Disadvantages: low development efficiency

High level language:

Features: use human-readable (English) characters to write programs

Advantages: high development efficiency

Disadvantages: slow running speed, which must be translated before the computer can recognize it, resulting in slow running speed.

It is concluded that the development efficiency is from low to high, the running speed is from low to high, and the difficulty of learning is from difficult to easy.

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