I'm not too experienced with code including external memory, but i believe there was an error with the code mixing that either mixed lines of code up or got rid of code to save files onto your device. Try looking up code for the device, see if that helps at all.
Answer:
An operating system is something that controls the functions of an application software(app). The app does specific tasks for the end-user; the end user is someone who is, or is supposed to, use a product. The app uses API to request services from the operating system. If the user is interacting direct with software, it is an application software.
Explanation:
