This is one fixed, front-facing 2D reconstruction of the cream Original-Odhner 239 in the supplied photograph. The mechanical arithmetic engine is retained from the earlier prototype. It is an interactive illustration, not a photograph overlay.
Set and calculate
Drag each of the ten numbered setting levers vertically, from 0 to 9. The ten-digit checking window above the levers follows your setting. Swipe up on the main crank to add one turn, or down to subtract one turn. In portrait, use CRANK UP and CRANK DOWN in the first row of controls. On the physical model, swipe up or down over the crank. Keyboard users can focus the crank and press Up or Down. A crank revolution updates the 13-wheel accumulator and 8-wheel revolution counter.
Move the carriage
Press either of the two black square shift keys at the front to move one decimal place. Alternatively press the small silver front release and drag the carriage rail horizontally. Eight detents provide seven single-column intervals. Both lower registers and their two clearing handles travel with the carriage; the lower apron stays fixed.
Clear and transfer
Tap the black input quick-clear thumb beside the main crank (or CLEAR INPUT in portrait) once. The app holds the thumb automatically, turns the main crank a quarter-turn clockwise, returns it home, and resets only the ten input settings. No two-finger gesture is necessary. Ordinary up/down crank swipes always add/subtract and never quick-clear. Crank swipes do not scroll the page. Turn the small left carriage crank to clear the revolution counter; the small right crank clears the accumulator. To back-transfer an accumulator value: quick-clear the setting, pull the small black transfer key near the result window, then turn the right clearing crank. Only values fitting the ten-digit setting register can transfer.
Example · 123 × 45
Set 123 using the three rightmost levers. Shift carriage to position 2 and turn the main crank four times clockwise. Return to position 1 and turn five more times. The counter reads 45, the accumulator 5535.