This program would tell the turtle to mine a cube with dimensions of 5 blocks on either side, and the turtle would mine these layers of 5 * 5 until it ran out of space and would return to the surface.
Another use of the mining turtle is of entertainment, a command that one can give is
The turtle then states "Preparing to get down" The turtle will then move in such a fashion it could be considered dancing. It will continue to "dance" until anything is typed into the robot again.
A Mining turtle can also be used to make a 2x3 tunnel. Simply type in Tunnel X where X = the number of blocks in length you want the tunnel to be. very useful for strip mining.
To refuel, just place fuel in its current selected slot in its inventory,open lua, and type
whereas if quantity is defined,it will consume the quantity entered,else it will consume all fuel in the selected slot
To see the Fuel Values, see? http://computercraft.info/wiki/index.php?title=Turtle.refuel#Fuel_Values
For more advanced stuff, see Turtle API.
One computer (7 stone, 1 redstone, 1 glass pane), 7 iron ingots, 1 chest, one diamond pickaxe