https://blog.csdn.net/linuxprobe2017/article/details/61616502
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If you have seen some desktop computers, most of them are like this. The keyboard, display, and case can be separated. Even if the case and the user are not in the same room, as long as the line is connected, the computer can still be used. In the early days, the chassis, keyboard and display were indeed separated.
Do you know the origin of the host, console, and terminal in Linux?
At the beginning of UNIX, computers were very expensive. There were no personal computers at the time. Most computers were large, expensive, and unstable machines that had to be stored in an environment with controlled humidity and temperature. Thompson of Bell Labs began to look for small and inexpensive computers. At that time, most computers cost US$100,000. In 1970, he and his colleagues got a PDP-11, which cost US$10,800. Within a few months, they ported UNIX to this computer . But PDP-11 can only run one program at a time, so they modified the UNIX system to enable it to run multiple programs at a time. This goal was not achieved until 1973.
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The origin of the host, console, and terminal in Linux The origin of the host, console, and terminal in Linux
As can be seen from the picture above, there are many buttons on the PDP-11 body, and this operation panel is called a console. The console is closely integrated with the host and cannot be operated remotely. Many operations need to be completed through the console (such as problems encountered during startup), because the terminal can only be connected when the host is started and the network connection is normal. Because the price of mainframe computers is very expensive, Thompson and his colleagues hope that UNIX can be called a multi-tasking (that is, running multiple programs at the same time), multi-user system. In those days, computers did not have independent keyboards, and because of their expensive prices, it was impossible for everyone to own a computer.
Thompson decided to use a cheap teletypewriter: Teletype. Until now, the text input and output environment in Linux and UNIX systems is still abbreviated as tty (TeleTYpe). Teletype is quite primitive, everything is mechanical except for the power supply.
The origin of the host, console, and terminal in Linux The origin of the host, console, and terminal in Linux
Let’s imagine that if many users each have their own Teletype, and the "computer room" (called the "glass house" at the time, because many companies used glass walls to display expensive large computers) had an expensive large computer PDP-11, this computer runs UNIX that can log in by multiple users, so that each user can access the main computer by using the cheap (compared to the mainframe computer) Teletype, which is equivalent to that each user passes the cheap price Own a computer. Yes, Thompson thought the same at the time, and finally realized it. This idea has a large number of applications so far, such as the relationship between servers and terminals.
The mainframe computer PDP-11 is called the host , and the user's Teletype is also called the terminal (originally referring to the end of the wire). Because the host and the terminal are separate, no matter whether the host is replaced or the user replaces the terminal, they are independent of each other. The host and the terminal can continue to develop along with the technological wave. Roughly speaking: computer = host + terminal; terminal = input device + output device. In this example, computer = PDP-11 + teletypewriter; and Teletype = input device (keyboard) + output device (paper).
Let's consider a situation. If there are multiple hosts in the computer room and multiple terminals use these hosts at the same time, how to connect to them? This will use the terminal server. The terminal server connects the host and the terminal, and the user only needs to input the host to be accessed, and the terminal server will establish the connection between them . As shown below.
The origin of the host, console, and terminal in Linux The origin of the host, console, and terminal in Linux
The above is the origin of the host, console, and terminal in Linux.
The origin of the host, console, and terminal in Linux The origin of the host, console, and terminal in Linux
Title picture: Ken Thompson (sitting), Dennis Ritchie (standing) and PDP-11 and Teletype 33-ASR. The source cannot be tested.
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"Terminal is an electronic computer or computer system that allows users to input data and display the results of their calculations. Some terminals are fully electronic, and some are electromechanical. It is also called a terminal. There are differences between independent computers." --- Wikipedia "Terminal" The
original UNIX-like systems were mainframe systems (and there was no concept of personal computers at the time. Apple and IBM were the driving forces of the development of two personal computers ), users It needs to be accessed through a terminal, remote and multi-user login to a large computer . Generally speaking, a terminal has no host, only a display, keyboard and mouse (mouse was a very advanced thing in that era). The mainframe itself does not have a monitor, keyboard and mouse.
Up to now, Linux also retains the concept of "terminal", and all user interactions access the system through the terminal mode. Including the X environment, it is also a special terminal implementation. Although now the computer uses the terminal to link itself.
For ordinary Linux, the terminal is generally a character (or simulated character) command interaction interface. Realize the control of the computer.
Many of the current terminals are " virtual terminals ".