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In the past, [[Unix]] and [[Unix-like]] systems used serial port devices such as [[RS-232]] ports, and provided {{Code|/dev/*|text}} [[device file]]s for them.<ref>{{Cite web|title=A Brief History of Terminal Emulation {{!}} Turbosoft|url=https://www.ttwin.com/blog/270-history-terminal-emulation|access-date=2021-10-04|website=www.ttwin.com}}</ref>
With terminal emulators these device files are themselves emulated by a pair of [[pseudoterminal]] devices. These in turn emulate a physical port/connection to the host computing endpoint
There are also special [[virtual console]] files like <code>/dev/console</code>. In text mode, writing to the file displays text on the virtual console and reading from the file returns text the user writes to the virtual console. As with other [[text terminal]]s, there are also special [[escape sequence]]s, [[control character]]s and [[System call|functions]] that a program can use, most easily via a library such as ''[[ncurses]]''. For more complex operations, the programs can use console and terminal special ''[[ioctl]]'' system calls. One can compare devices using the patterns vcs ("virtual console screen") and vcsa ("virtual console screen with attributes") such as <code>/dev/vcs1</code> and <code>/dev/vcsa1</code>.<ref>{{cite web|title=Screen dumps|url=https://tldp.org/HOWTO/Keyboard-and-Console-HOWTO-20.html|access-date=2008-07-31|work=The Linux keyboard and console HOWTO|publisher=The [[Linux Documentation Project]]|quote=The current contents of the screen of /dev/ttyN can be accessed using the device /dev/vcsN (where `vcs' stands for `virtual console screen'). [...] From a program it is usually better to use /dev/vcsaN (`virtual console screen with attributes') instead - it starts with a header giving the number of rows and columns and the ___location of the cursor. See vcs(4).}}</ref>
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