why the heck, someone should use a dos system, or even dos apps, inside an
emulator? first of all you shouldn't ask this, cause you are reading an
emag in 2018 :p hahahaha

but to answer the question...

first of all there are many good dos applications that can be used even
today. ok... ok... ok... you should have the "command prompt" inside you
to use them, but if you do, you can use some of them even today,
specially if you have an old pc, which is too slow.

ms-edit
my favorite app from dos is ms-edit. i hate ms, but this editor, is
something else. i don't know if its the ui, the memories from the old
times or that this editor just rocks! simple but with the basic functions
that every editor should have and you can even use mouse.

wordperfect
this is my favorite word processor. if i want to right a text document in
plain ascii, with 80 chars width, this is my choice (after my own editor,
but this is another thing ;) ). a little awkward to use in the beginning
but after you know it, its straight forward.

hex editors
even today, dos hex editors are simple and powerful. even in linux i
can't find one that's so good, as a dos hex editor, except in a gui form.

music playback
ok... i admit... you wont launch a dosbox instance just to hear some
mp3s, but to play .mod and .mid files, i think its the best way ;)

trackers (mod)
making music with a tracker, is 100% a dos thing...

8bit graphics
you are in the retro gaming thing... and want to make some 8bit or
8bit-ish style graphics? then deluxe paint is the solution for you. u
can't use photoshop to create 8bit graphics. you need the original
program for that and this can be done in dos only!

retro gaming & programming
if you want to make a retro game, in old style, you can use dos with
various programming languages like pascal, basic or even assembly. just
look what the "8-bit guy" is doing here:

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 ÜßÜßÜ ²±° Planet X3                                                   °±²
 Û Û Û ²±° www.kickstarter.com/projects/1973096722/planet-x3-for-ms-dos°±²
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useful sources

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 ÜßÜßÜ ²±° DOS Programs                                                °±²
 Û Û Û ²±° dosprograms.info.tt/                                        °±²
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 ÜßÜßÜ ²±° Dos Heaven                                                  °±²
 Û Û Û ²±° www.doshaven.eu                                             °±²
Ü ß ß Ü