Line - Yamaha V9938 Programmer's Manual

4.4.9. LINE

LINE command is used to draw straight line in VRAM of expansion RAM. The line
drawn is the hypotenuse of the triangle defined by the "long" and "short" sides. The
distances are defined from the single starting point. Words "long" and "short" are used to
identify respective sets of registers to use to define triangle's sides: long side is defined in
registers R#40 and R#41 (by 10 bits MJ9...MJ0 with value in the range 0...1023) and short
side is defined in registers R#42 and R#43 (by 9 bits MI8...MI0 with value in the range
0...511). The units used are dots.
(DX, DY)
LINE 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
© 1985 ASCII CORP. / NIPPON GAKKI CO.
Video or expansion RAM
Maj
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
↑
DIY
Min
→
DIX
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
Page 85 of 108
1 0 LSB
DX1 DX0 DX: Starting
point X
0 DX8
DY1 DY0 DY: Starting
point Y
DY9 DY8
NX1 NX0 Maj (NX): long
side dots num
0 NX8
NY1 NY0 Min (NY): short
side dots num
NY9 NY8
© 2010-2015 Eugeny Brychkov