Hmmv (High-Speed Move Vdp To Vram) - Yamaha V9938 Programmer's Manual

4.4.4. HMMV (High speed move VDP to VRAM)
HMMV command is used to paint in a specific rectangular area in the VRAM or
expansion RAM. When using this command, note the limitation on the X coordinate in
various modes (255 or 511).
HMMV execution order
Step 1: Set necessary coordinates in command registers
MSB
R#36
R#37
R#38
R#39
R#40
R#41
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)
Step 2: Set color register value
The first byte transferred from CPU after starting executing the HMMC command
should be located in color register R#44 (CLR). Format of color data depends on the
graphics mode.
© 1985 ASCII CORP. / NIPPON GAKKI CO.
VDP
7 6 5
DX7 DX6 DX5
0 0 0
DY7 DY6 DY5
0 0 0
NX7 NX6 NX5
0 0 0
NY7 NY6 NY5
0 0 0
Video or expansion RAM
(DX, DY)
NY
↓
4 3 2
DX4 DX3 DX2
0 0 0
DY4 DY3 DY2
0 0 0
NX4 NX3 NX2
0 0 0
NY4 NY3 NY2
0 0 0
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NX
DIY
1 0 LSB
DX1 DX0 DX*:
Destination X
0 DX8
DY1 DY0 DY: Destination
Y
DY9 DY8
NX1 NX0 NX*: Number of
0 NX8 dots in X-axis
NY1 NY0 NY: Number of
dots in Y-axis
NY9 NY8
© 2010-2015 Eugeny Brychkov
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