What is meant by scan code and refreshing of the screen

Question

What is meant by scan code and refreshing of the screen?

Answer 1

When a key is clicked on keyboard, the keyboard controller positions a code carry to a key pressed into a part of memory known as keyboard buffer. This code is known as scan code.

For maintaining picture on screen, some of the methods are required. On screen refreshing is done by keeping phosphorus radiant to redraw picture repeatedly that is by quickly directing the electronic beam back to same points.