Ymmm (High Speed Move Vram To Vram, Y Only) - Yamaha V9938 Programmer's Manual

4.4.2. YMMM (High speed move VRAM to VRAM, Y coordinate only)
YMMM command is used to transfer data from the area specified by DX, SY, NY, DIX,
DIY and the right (or left) edge of the screen, in the Y-direction determined by DY.
YMMM execution order
Step 1: Set necessary coordinates in command registers
MSB
R#34
R#35
R#36
R#37
R#38
R#39
R#42
R#43
*In G4 and G6 modes, the lower one bit, and in G5 mode, the lower two bits are lost in registers related to
X-coordinate (DX, NX)
© 1985 ASCII CORP. / NIPPON GAKKI CO.
Video or expansion RAM
↓
DIY
7 6 5
SY7 SY6 SY5
0 0 0
DX7 DX6 DX5
0 0 0
DY7 DY6 DY5
0 0 0
NY7 NY6 NY5
0 0 0
(DX, DY)
↑↑
(DX, SY)
NY
4 3 2
SY4 SY3 SY2
0 0 0
DX4 DX3 DX2
0 0 0
DY4 DY3 DY2
0 0 0
NY4 NY3 NY2
0 0 0
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→
DIX
1 0 LSB
SY1 SY0 SY: Source
transfer point Y
SY9 SY8
DX1 DX0 DX*: Source
0 DX8 transfer point X
DY1 DY0 DY: Destination
transfer point Y
DY9 DY8
NY1 NY0 NY: Number of
dots in Y-axis
NY9 NY8
© 2010-2015 Eugeny Brychkov