Using gasses swirling around similar to a gas-giant to play moving images or static images, making a reality television because it does not create different colored light artificially as in light bulbs, LEDs, or television tubes, but instead emits light dependent on the different colors of the gasses, meaning reality plays the images. Gasses can be lit up in different energy levels to create more vibrant colors.
Solid and liquid would work similar to gas, and space would be for all matter types because all matter emits electrons or lower light particles. The brain would save all different types differently, getting different theories and outputs.
Advent Guard Note: They could have made functional calculator boards from gas before the 1800 century. As you write on the board it turns the gas you touch into plasma, making it stand out from the rest of the swirling gas. When you wish to change colors you empty the chamber of the gas inside and refill it with the color you want, as the lines you have already drawn stay there as plasma inside indents in the screen similar to pixels to keep them in position as electricity is pumped through on every side except the bottom and top holding the gas in place, as the rest of the gas leaves. As the technology improved and the lines became thinner and more precise it would eventually catch up to what could be done on boards. The screen would be able to be saved by keeping electricity running through it as you replace the screen with a new screen and put the old screen into savings.
Advent Guard Note: This time of history is known as the Gas screen period for the classified of Earth, or also known as the General is an asshole screen period because only rich people even knew this technology existed and got to use it to improve and build their and their families lives. But our books will probably just say the more fantasy steam punk version our scientists imagine as they make gas screen technology in the modern day, without realizing and truly understanding that scientists had to have had created gas screen technology centuries before on Earth in classified. Without the true knowledge of our history, our society can only possibly go in a different direction as the direction that the classified people are going, which makes us forever different.