Currently I'm investigating about NCurses library for implement text user interface in C programming language.Curiously today I went to a Car'ls Jr and and there was a monitor like this:Now, my question... is this a terminal application (TUI), why this kind of companies (fast food) use text based applications (it looks like 90s) and not a modern applications that the employees can watch and understand more quickly through images, and what are the technical advantage of using this kind of applications?. 
Why McDonal's, Carl's Jr, etc. use TUI based applications?
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First of all, that is an example of a GUI, not a TUI. Note that it uses proportional fonts with different sizes, and 3D borders. Second, note that this user interface is an information display  there's no user interaction here. And while it looks dated, the design is well done. If it ain't broke, why fix it?The design uses a card metaphor to visualize a queue of orders. The oldest, most urgent order is at the top left, and shows the order number, elapsed time since the order was placed, and ordered items. At the bottom right, all items are aggregated into a list so that they can be prepared more efficiently. If there are seven orders on the display for wings, the cook doesn't have to count that themselves. They can see everything at a glance. This allows staff to answer their important questions immediately:What item do I have to prepare next? Easy, look at the summary on the bottom right.Who are these items for? Easy, look at the top-left card, collect the items, and deliver them to the customer with that number.Would a more modern design help here? I doubt it. Aside from some colour choices (red on blue? ugh), it is very legible, contains little unnecessary information, and wouldn't really be that different. Here's a mockup inspired by the Material Design language:Well, that does use badges, but wouldn't benefit from any icons or images. It really is the same thing as before. In fact, there's more wasted space now, and it is arguably more difficult to read at a glance (I'm not a good designer).For new development, text UIs still have their place: Is the program used primarily by sysadmins over SSH? A GUI would be unhelpful there: terminal-based programs require less bandwidth and don't require a graphics stack on remote machines.Some (older) text-based programs also have a significant following (vim, mutt, emacs, irssi, ). Due to their long history, they are often more feature-rich than GUI-based alternatives. Power-users also appreciate that they (by design) can do everything via keyboard shortcuts.Aside from these factors, GUIs are far more flexible than TUIs, and not much more difficult to create. The big advantage of GUIs is that they can be more self-describing. Instead of having to memorize various shortcuts, users can see tooltips, navigate menus, click on icons, . That's particularly friendly for casual users.But these arguments don't apply with your example: there's no user input on that screen (I think), and the users of that interface are professional users. Sparing a couple of minutes to help them understand a high-information-density display is probably better than a low-information-density display that still needs some explanation.