There are 8 of these , and they are all a maximum of 8 x 8 pixels. This contains the sprite graphic data, orientated for the current horizontal position. The address is determined by the high bit of the direction byte. Current direction is stored in the lower 4 bits. I have no idea what the function of this byte is.
Drawing is done slightly differently.
First you select your sprite object, this is done by putting a value from 0 to 7 in R9. You are now ready to work with the graphics. Here are the sprite commands. For directions, see above. Using the sprite data pointed to by the index register, exclusive-or it into the sprite buffer.