(screen screen X coordinate)
＝= Xst + △ Xst × (V counter value) + △ X × (H counter value) 

(Screen screen Y coordinate)
＝ Yst + △ Yst × (V counter value) + △ Y × (H counter value) 

(Coefficient table address)
＝ KAst + △ KAst × (V counter value) + △ KAx × (H counter value) 

∙ By setting the rotation parameter read control register, Xst, Yst, and KAst can be read from other than the first line. The values ​​after the second line of Xst, Yst, and KAst when DXst, DYst, DX, DY, DKAst, and DKAx do not change in one screen are expressed by the following formula.

 (screen screen X coordinate)
= Xst
＋＋ Xst × {(V counter value) − (V counter value when Xst is read)}
＋ △ X × (H counter value) 

(Screen screen Y coordinate)
= Yst
＋＋ Yst × {(V counter value) − (V counter value when reading Yst)}
＋ △ Y × (H counter value) 

(Coefficient table address)
= KAst
＋＋ KAst × {(V counter value) − (V counter value when KAst is read)}
+ △ KAx × (H counter value) 

Rotating scroll screen has two sets of parameter tables called “Rotation parameter A” and “Rotation parameter B”. The screen display of RBG1 is performed by rotation parameter B. RBG0 can specify which of the two sets of parameter tables to use, or switch between them on the display screen. This allows RBG0 to simultaneously display two different rotating scroll screens in one screen.
Also, the rotation parameter table always has two sets of rotation parameter tables