Prototypes of a modern calculator could be coded in Java-Script or Dart and presented
on a browser.
Also, my understanding is that phones, tablets and the like are not allowed in classrooms precisely because their broad programmability makes it easy for students to cheat. How hard would it be for a student to flip back and forth between an app that looks like a calculator and a browser window with all the answers in it? Hardware calculators offer educators some assurance that this isn't happening.