Paint holds
Holds are named column letter (A–K) + row number (1–18). A1 is bottom-left, A18 top-left.
Nothing saved yet.
Tapping a problem loads it onto the board — and sends it instantly if you're connected. A dropped library is kept on this device; a problems.json served next to the app loads automatically.
Light one LED to check the wiring matches. Enter a position (1–198) or a cell.
If the wrong LED lights, your box is wired differently — try the flips below, then re-test.