Is it possible to save something that is typed on an Arduino with a keyboard and a small LCD screen as a .txt file on an SD card or flash drive?
An Arduino with a keyboard, an LCD screen, and an SD card. Sounds like a mighty small computer.
Yes, it's possible to save data to an SD card. The extension on the file name, and the contents of the file are up to you.
So is the extension something that's done in the Arduino or on whatever computer the file gets transferred to via the SD card?
It's done on the Arduino, when creating the file on the SD card.
ok, looks like I need to look up more stuff on how to use the SD cards. At least modding the card reader and waiting for the LCD screen to arrive will give me enough time for that.