On the Subject of Holographic Memory

Polarising views since 1898.

This module consists of two screens and a 4×4 grid of tiles.

Each tile has two sides with a unique image on each:

• A light side where the background is brighter than the image.
• A dark side where the image is brighter than the background.

Only one side is visible at a time. Tilt the module to reveal the other.

Once every image has been memorised, press any tile to start up the module.
All images will disappear from the grid and the two screens will display a pair of images from the grid.
Only one tile should be pressed per stage. In order to figure out which:

1. If the display is a number, substitute an image from the corresponding previous stage:
   • If the number is solid, substitute the image that was selected at that stage.
   • If the number is empty, substitute the image that was displayed on the other screen at that stage.
2. The column of the required tile is the same as the column of the image displayed on the top screen.
3. The row of the required tile is the same as the row of the image displayed on the left screen.
4. The tile must display the correct side when it is selected:
   • If both displayed images are from the same side of their respective tiles, the required tile must also display that side.
   • Otherwise, the required tile must display the opposite side from the previously selected tile.

If an incorrect tile or incorrect side is selected, the module will reset, revealing the images on the grid once again.