Simplest form of graphical output is a light with a label underneath

(Light) - Power

Sometimes light can blink or change color to indicate more but it is very limited
You can expand to multiple lights with labels but still limited and for specific purpose

If you are able to light up lines, you can write a decimal digit with 7 segments, the 7-segment display like a calculator.

With even more segments, you can even create letters
This starts to be more flexible and allows for changing the purpose of the display if you run a different program

Initially it would be very expensive to have mutliple lines showing at the same time since you would need multiple rows of these displays

Early on you could repurpose another device, the typewriter
The typewriter allows you to push a key that causes a hammer to slam ink into paper and moves left and right but also allows the paper to roll out so additional lines can be printed while allowing previous lines to be seen

By connecting the typewriter to a computer, the computer could control the typewriter to display lines and also listen in to which keys the user hit on the typewriter as input

This is an early form of terminals, consoles, and text-based interfaces

However, typewriters work fine for text based output, but for diagrams they are not very accurate
Diagrams can be approximated by text with many different symbols (pipes, asterisk, slashes) and early user interfaces would still use them to draw boxes, but for anything more detailed text wouldn't work

How would a human draw a diagram? Using a pen and paper you could sketch out a diagram

What if we automated that (pen plotter)?


- Do we move the paper? Or pen?
- What if we want to move the display? What about paper?
- Could we do it with lights?
- A projection of lights? Laser!
- Fill the screen? Solid rectangles?
- Moving lights? Rotating in a circle?
- A static grid of lights?
- Need to go from shape to grid. Rasterization!
- Plotting