I need a way to find if the character ('<') has hit a wall (Black pixel Graphic) -On a ZX81 game. I'm been looking at another game... which uses code if peek(peek 16398 +256*peek 16399)...

I need a way to find if the character ('<') has hit a wall (Black pixel Graphic) -On a ZX81 game. I'm been looking at another game... which uses code if peek(peek 16398 +256*peek 16399) = cod...