It probably has a character mapped display, so you can only display 256 different (ascii and graphics) characters in a memory mapped 80*25 = 2000 bytes display

It probably has a character mapped display, so you can only display 256 different (ascii and graphics) characters in a memory mapped 80*25 = 2000 bytes display buffer. EDIT: I can now see that is does have bit mapped graphics. It must have a built-in serial like terminal with graphics capabilities. EDIT2: Probably using this chip: https://www.adafruit.com/product/1590 https://www.adafruit.com/product/1590 :-)