Fruit Jam OS features a built-in Editor app which allows you to view and edit code and other text based files on the Fruit Jam's drive. The Fruit Jam OS Editor is loosely inspired by GNU Nano but does not support all of the same features or hotkeys. 

To edit the code.py for a specific app, choose the app in the launcher and then press the E key. To open any arbitrary file, choose the Editor app icon and press Enter. When you launch the Editor by its icon, it will open a file chooser that lets you select a file to open from the CIRCUITPY drive.

Along the bottom of the editor is a system bar which has inverse coloring from the rest of the editor space. This bar shows the currently open file, the drive mount state (RO for readonly or RW for read/write), hotkey reminders for the available actions, and in the bottom right, the current x, y position of the cursor.

Navigation & Usage

The primary navigation and control within the Editor is done with a USB keyboard. Use arrow keys to move the cursor around the screen. Type letters, numbers or characters to write into the file at the cursor's location. There are a number of Ctrl+[Key] hotkeys available as well:

• Ctrl+W - Toggle the readonly state of the drive. By default in CircuitPython the drive is mounted read-only so the editor will be unable to save modifications to files. Pressing Ctrl+W will reboot the Fruit Jam with the drive mounted writeable, and launch back into the Editor with the same file open so that you can make edits and save them. Pressing Ctrl+W again would then reboot and toggle back to readonly. See the Storage page in the CircuitPython essentials guide for details on storage mounting. See the Boot Sequence page in this guide for details on how Fruit Jam OS facilitates the toggling of readonly mounting.
• Ctrl+R - Run the current CircuitPython code file. This will also set up arguments for the launcher that will cause it to automatically launch back into the editor with the current code file the next time the launcher is run. So the app will launch, and then when it finishes or exits by the user, the Editor will open back up showing the same file. This makes a iteratively developing a CircuitPython script more convenient.
• Ctrl+O - Open a new file. This will show a file chooser which may be navigated with up/down arrow keys. Press Enter to open whichever file is currently selected.
• Ctrl+F - Find some text within the file. Pressing Ctrl+F will temporarily change the system bar to an input so you can type in a string to search for. When you press Enter, the file will be searched for the input string and, if found, the cursor will move to the next instance of that string within the file.
• Ctrl+G - Go to line number. Pressing Ctrl+G will temporarily change the system bar to an input for the user to type a number into. When you press Enter the cursor will move to the line number you gave.
• Ctrl+C - Quit the editor. Pressing Ctrl+C will exit out of the editor app and go back to the launcher.

The next two hotkeys are only available if the storage drive is currently mounted writable. They are not available when the drive is read-only.

• Ctrl+S - Save the current file to the drive.
• Ctrl+X - Save the current file to the drive, and exit the editor app.

Optional Mouse

If you have both a USB keyboard and a USB mouse connected to the Fruit Jam, then the mouse can be used to move the cursor within the Editor. Move the mouse pointer to where you want the cursor and then left-click.