By not expensive do you mean free
Hmm.
I think it is called a "computer".
And the display is called a "monitor" usually using Liquid Crystal Display, LCD.
They had this "app" back in the TRS-80. Trandy Radio Shack, 1980.
I hook my laptop to my TV and use a wireless mouse
There is a mistake on the chess monitor. The king and queen are swapped
Enjoying chess on the big screen is a great pleasure.