For perspective, the original Apple II computer typically had 48KB RAM, a 140KB floppy disk, and a 1MHz CPU. Yet it ran VisiCalc (the first popular spreadsheet program), Bank Street Writer (a marvelously easy-to-use word processor), and plenty of now-classic video games.

Few (except maybe dmitrygr!) would recommend a microcontroller today if your goal were to build a spreadsheet or word processor app. But you'd be amazed how much business logic you can stuff into such a small space, as long as your requirements are focused.