02. Understanding of computer composition and operating systems, understanding of programs, OS development history, and miscellaneous

Computer Register Controller Operating System Development History

Ma GE has talked a lot about it and can understand it, but I need to remember a few things. However, I still drew a picture based on my understanding of the computer, which is not necessarily accurate, but it is similar,

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The bottom layer of the computer is composed of five components: the host, controller, memory, input device, and output device.

The memory and controller are in the CPU, the memory is responsible for computing, the Controller is responsible for controlling the program flow, and the data in the memory,

Beiqiao is a high-speed I/O device that is usually used to connect to memory, hard disks, graphics cards, and other devices that require high-speed I/O. The data in the memory is also read through beiqiao to the CPU cache, then read the Register through the CPU cache. nanqiao is a low-speed I/O device, which is usually used to connect the mouse and the keyboard. It is connected to beiqiao (not previously ..)

The upper layer of the hardware is the operating system, and the operating system is responsible for controlling the hardware. The operating system also provides some of the simplest programming interfaces. The Library is composed of these simplest programming interfaces, it can complete some more complex operations. The Library is also called the application programming interface. It provides many APIs, and the application completes related operations through the Library call or direct call, shell is also an application ..

Let's talk about the CPU command level,

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X86 series CPU commands are divided into four levels: ring0, ring1, ring2, and ring3. ring1 and ring2 are not used for historical reasons, and ring 0 is called the privileged mode, the commands in Ring 0 can only be called by the operating system. These commands generally control the memory, hard disk, and the like. These commands cannot be directly executed by the program to prevent malicious programs from damaging the system, this is a kind of protection for the CPU, and the loop 3 command can be directly called by anyone, and can be used as a user interface.

Programming:

Computer languages include interpreted and compiled languages.

Interpreted language: the source code is not compiled into a binary file at a time, but interpreted by the interpreter to run the intermediate code.

Ypthon, Shell, Ruby

Compiled language: Compile the source code into a binary file at a time and execute it directly through the CPU.

C, C ++, Java, C #

Program compilation process:

Edit --> compile --> link --> RUN

However, this process is troublesome. Some integrated development environments, such as Vs and codeblock, are available at will.

OS development history and Linux version:

1, GE, Bell, and MIT jointly developed the multics operating system in 1956.

2. In 1969, the Bell lab first withdrew from multics development,

3. In 1970, Ken Thompson in beel lab developed a simple operating system on a PDP-7 in order to make his game Star Wars run normally.

4. ge withdrew from multics R & D in 1970

5. In 1973, Ken thonpson and Dennis Ritchie thought that the operating system written in assembly language was portable, so they changed the current BCPL language, which is the current C language, then a portable operating system is developed in C language and named Unix

6. In 1974, Ken thonpson and Dennis Ritchie jointly published a paper. Since then, Unix began to become popular. However, Bell was unable to sell the operating system because at&t was sanctioned by the U.S. anti-monopoly law, in addition, the system must be provided free of charge to various research institutions.

7. In 1977, BSD was formally established. He was an Organization designed to study Unix systems, but he sold the system for money, which also upset Bell's lab. For this reason, he fought a 10-year verbal war with BSD.

8. In 1980, personal PC emerged. At that time, IBM urgently needed a personal PC operating system, microsoft Bill Gates sold an operating system qdos from Tim Paterson, a programmer in Seattle for $5, and renamed it dos to be authorized for IBM, the authorization price for each computer is USD 5.

9. In 1983, Apple began to develop an operating system with a graphical interface. At the same time, Microsoft also obtained an operating system source code from Apple through various means, after modification, windows was developed using DOS as the kernel, while Apple also developed Mac OS based on Unix kernel.

10. In 1991, Linus developed the Linux Kernel on a ipvsx learning compatible machine like minix and published the kernel on the Internet to comply with the GNU protocol. This also attracted the attention of the GNU software organization. At this time, GNU urgently needed a kernel of its own operating system ~~, They just made a close hit ., This also contributed to the current Linux.

11. In 1993, Linux 1.0 was officially released. And Application and production work in progress

Miscellaneous:

Common CPU

CPU: x86, X86-64, power, PowerPC, Alpha, Anta, ultrasparc, arm, MIPS, m68000

Human-Computer Interaction Interface: Shell

Gui: graphic user interface: graphical interface

Windows

IOS and Android

X-Window

Gnome

KDE

Xfce

CLI: command line interface: Text Interface

Powershell

Bsh

CSH

Tcsh

Ksh

Bash

Zsh

Linux Kernel: www.kernel.org

Linux terminal:

Serial terminal: (a terminal on the plain text interface. The graphic interface cannot be displayed)

/Dev/TTYs #

Physical terminal:

/Dev/console

Virtual terminal: CTRL + ALT + F [1-6]

Graphical terminal: CTRL + ALT + F7

Startx &

/Dev/tty #

Pseudo Terminal (analog terminal): remote connection, open command interface in graphic environment

/Dev/pts /#

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02. Understanding of computer composition and operating systems, understanding of programs, OS development history, and miscellaneous