It would have been funny to read a code with more than 2 - counting how many "r"s  are in it to get known what it'll do...

That would be annoying. Anyway, the 2 ^rs are for the two buffers: the main buffer and the back buffer.

Isn't it actually frontbuffer, buffer and backbuffer? Since no 'r' should be the main buffer, right?

I think that Dispgraphrr just tells Axe to display in 4 scale greyscale, and ClrDrawrr tells it to clear both buffers.
And by the way, Pt-On() can only have a max of one r

its quite simple actually. its whether a buffer is turned on or off (1 or 0). And Dispgraph, Dispgraphr, Dispgraphrr, will show 2 scale, 3 colour greyscale and 4 colour greyscale respectively.

If you are not using Fix 5, then just use Text(X,Y,stuff to display) after your DispGraph, it should flicker a little, but it will be black
Or, just use Text():Text()r if you are using Fix 5, with the correct arguments of course.