Need help making a upscrolling 4x20 display

Hello, everybody.
I'm working on a basic computer and i'm using the adurino uno as the processor core.
I want to let the output scroll up on a new line.
the lcd is hitachi hd... compatible

the function:

static void printCharOnLcd(char c) {

// i get allways one char at once and the char 10 on new line
//and i need backspace function on char 8