I think that the 'EXP' you store to it is a pointer representing picture or sprite data.

This displays the 768 bytes pointed to. This is useful if you absorb a picture file into your program at the start of it, as you can easily display that picture to the screen. Whatever 768 bytes that are pointed to will be displayed, whether or not it's picture data you want.

By the way, you should be aware that it does not store it in L6, and you can't add sprites or text or anything on top of it.  It's only real use is for a splash screen.  If you want to change what is onscreen outside of the picture, you should use conj(Pic1, L6, 768.  Change Pic1 to the pointer to your picture.

Right.  However, DispGraph will overwrite it.  If you use Exp→DispGraph, you cannot modify what shows up onscreen unless you change the value at Exp.
DispGraph itself is essentially L6→DispGraph

Well, writing directly to the LCD means that you have to read from LCD RAM for things like Pxl-Test, and displaying sprites without overwrite logic would have to do the same thing, which means it would be much slower, and you would have to worry about the LCD delay, too.

So if you had a splash screen stored to, say, Pic1 and said Pic1->DispGraph, it would show Pic1? But I thought you could only store 8x8 sprites to pic pointers...? confused >.<

So if you had a splash screen stored to, say, Pic1 and said Pic1->DispGraph, it would show Pic1? But I thought you could only store 8x8 sprites to pic pointers...? confused >.<

If you absorb a Pic into the source you can recall it in that manner.