Fill.asm: This program illustrates low-level handling of the screen and keyboard devices. In particulate, the program runs an infinite loop that listens to the keyboard input. When a key is pressed (any key), the program blackens the screen, i.e. writes \"black\" in every pixel. When no key is pressed, the program clears the screen, i.e. writes \"white\" in every pixel. The white must fill in backwards, starting at the end of the black section. Pressing a key continuously for long enough should result in a fully blackened screen, and not pressing any key for long enough should result in a fully cleared screen. A test script (Fill.tst) is provided in the Project 4 folder, but no compare file. The program should be checked visually by inspecting the screen of the CPU Emulator.