Commodore Plus 4 - Page 403

The Joystick Ports 391
numeric value depending on the state of the joystick. The following table lists the
possible values returned:
Value
0
1
2
3
4
5
6
7
8
Joystick State
neutral
up
up and right
right
down and right
down
down and left
left
up and left
In addition, when the fire button is pressed, 128 is added to the values listed in the
table.
Example: This program plots and unplots a circle on the high-resolution graphic screen.
Whenever the joystick in port 1 is pushed away from neutral, the circle is moved
in a corresponding direction. Whenever the fire button of the joystick in port 1 is
pressed, a circle is plotted and remains in place. To exit, press the space bar.
10 P0RI=lT08:READDX(I),DY(I):NEXT
20 GRAPHIC1,1
30 CIRCLE1,160,100,10,10
40 SSHAPEC$,150,90,170,110
50 GSHAPEC$,150,90,4
60 X=150:Y=90
70 GSHAPBC$,X,Y,4
80 GSHAPEC$,X,Y,4
90 GETA$:IFA$=" "THEN150
100 J=JOY(1):IFJ=0THEN70
110 IF(JAND128)=0THEN130
120 GSHAPEC$,X,Y,4
130 J=JAND15:X=X+DX(J):Y=Y+DY(J)
140 GOTO70
150 CHAR1,1,23,"HIT KEY"
160 GETKEYA$:GRAPHIC0:END
170 DATA0,-1,1,-1,1,0
180 DATA1,1,0,1,-1,1,-1,0
190 DATA-1,-1
Line-by-Line Explanation
10 Read in the amount to change x- and ^-coordinates based on JOY
value.