SEGA SATURN DEVELOPER'S MANUAL

● Frame buffer The: frame buffer is divided into a display frame buffer and a drawing frame buffer. Read / write access from the SCU to the frame buffer is performed only for the drawing frame buffer. The display frame buffer is a back bank and cannot be accessed.

By reading the frame buffer, you can enlarge, reduce, and rotate the entire frame buffer plane by giving displacement in the X and Y directions that specify where the readout start coordinates and the next readout dot are. I can do it.