Commodore VIC-20 User Manual page 222

208
The VIC 20 User Guide
710
FOR
1=7168
TO
7183 :
READ X : POKE I,X NEXT I
720
DATA
3,3,3,1,7,15,23,23
730
DATA
128,136,136,8,248,1'2,1'2,1'2
740
REM LOAD BOTTOM HALF OF PLAYER
750
FOR
1=7344
TO
735' :
READ X : POKE I,X NEXT I
760
DATA
19,19,2,2,2,2,6,O
770
DATA
128,128,128,128,128,128,192,0
780
REM LOAD 'EXTRA ARMS,'
790
FOR
1=7192
TO
7207 :
READ X : POKE I,X NEXT I
800
DATA
128,128,132,8,240,1'2,192,1'2
810
DATA
128,128,128,O,252,192,192,192
820
RETURN
When you run the program, the stick man on the left side of the screen
starts waving. After a moment, the one at the right starts to wave back. Then
the man on the left stops waving, followed by the one on the right, and the
cycle repeats.
The three subroutines that make the men wave (lines 210,310, and 490)
are the key to the motion. The first one, starting at line 210, makes only the
figure on the left wave.
The second subroutine, which begins with line 310, causes both ofthe
men to wave. Notice that the man on the left moves, then the program
pauses for about half the time it did when moving just one arm before
moving the man on the right. After the right-hand man's arm moves, the
program again delays only half as long as before. This keeps the men moving
at about the same speed, even though both are waving together. The man on
the right also waves in the opposite direction from the man on the left, so
they don't appear to be moving in "lock-step" with each other. These small
differences make the display more interesting.
The last subroutine, starting at line 490, moves only the right-hand stick
man, so the one on the left stops waving.
HIGH·RESOWTION GRAPHICS
With high-resolution graphics, your program deals with individual
dots on the screen, instead of characters. High resolution can be used to
draw finer lines on. the screen or to smooth the motion of a player, since it
can move in increments of one dot, instead of a whole character space.
Using high-resolution graphics on the VIC is much like using custom
characters. In fact, to the VIC chip, they are exactly the same; the standard
character display is a high-resolution display. The main difference is one of