Once upon a time, text terminals were the state of the art for communicating with computers. They were far more convenient than ancient technologies like paper tape and punch cards. Today, hardly anyone makes terminals any more, yet the technology is far from dead. Every major operating system offers one or more terminal emulator applications, letting users type in command lines and get back text responses.
System administrators use terminal emulation a lot; there are some things they can’t do any other way. Software developers like the command line interface because it lets them get closer to the underlying system software. Many computer geeks consider the ability to use the terminal fluently a minimum requirement for admission into their circles.
A terminal emulator can talk to the computer it’s running on, in which case it’s often called a console. It can also talk to other computers through a secure channel. On Linux, the command line often is the best way to do things, and on Windows and OS X, some tasks still work best with the console. Terminal emulators are even available on smartphones, though typing at them isn’t much fun.
To set up a terminal connection to another computer, you use the SSH (Secure Shell) protocol. It will encrypt the data between the machines, so no one can steal information such as passwords. Some older terminal emulation software uses the unencrypted Telnet protocol, but it should be used only when there’s no choice and a secure line is available. Terminal emulators also provide a variety of ways to transfer files between two machines, such as sftp and rsync. These require compatible software on the host computer.
On Windows, the name of the built-in console is Command Prompt. To run it, click the Start button and then All Apps. From there go down into Windows System and select Command Prompt. This will bring up a window that looks like what you would have seen on an old MS-DOS machine.
If you want an SSH terminal connection from Windows to another computer, a popular choice is PuTTY. The name doesn’t stand for anything, except that “TTY” used to be a common abbreviation for “teletype.” It’s free software.
Mac OS X comes with a terminal emulation application, logically called “Terminal,” located in /Applications/Utilities. It runs as a console on its own machine, and you can use the “ssh” command to connect to other computers.
Linux offers a variety of terminal emulators. Every GUI version of Linux comes with a terminal application, usually called “Terminal,” but there are many alternative terminal emulators. Unix and Linux computers using the X Window System use the xterm terminal emulator.
What exactly does a terminal emulator emulate? Most of them offer several choices. They can emulate one or more of the hardware terminals that used to be popular, such as Digital Equipment Corporation’s VT100 and IBM’s 3270, as well as the xterm application. Except when emulating proprietary protocols like the one for the 3270, they usually follow the ISO 6429 standard for controlling the appearance of text and movement of the cursor. You’ll often hear this called ANSI compatibility, because ISO 6429 grew out of the earlier ANSI X3.64 standard. It’s also called ECMA-48.
While the old terminals typically offered just one color, usually green or amber, today’s terminal emulators have access to all the monitor’s colors. Inevitably, some of them get carried away with bad color combinations. A good emulator gives the users some options, including conservative, readable color choices.
The original terminals communicated in the ASCII character set, or in one of the many extended ASCII variants that competed at the time. Modern emulators can communicate in Unicode as well.
Terminal emulation software may seem old-fashioned, but it’s still an important part of today’s software. Check out our website to learn more about terminal emulation software.