Texas Instruments TI-99/4A - CHAPTER 5 SOFTWARE

Bouncing Ball
If the new ball position is still on the screen, then the screen is
cleared to erase the old ball location Thp h;:; 11 i<.; thpn r1ic::pIRy~r1 M
the new location designated by Y and X.
These statements change the direction of the ball if X is out of
range. The CALL SOUND statement produces the "bouncing"
tone. Lines 330 and 340 check to see if Y is also out of range. If it
is, the pro~am transfers to change the Y direction. If not. the
program transfer's to line 220 to compute a new ball position.
These statements change the direction of the ball ifY is out of
range. The CALL SOUND statement produces the "bouncing"
tone.
The program then transfers to line 220 to compute the new
ball position.
User's Reference Guide
Examples:
>280 CALL CLEAR
>290 CALL HCHAR(Y,X,96)
>300 GOTO 220
>310 XDIR=-XDIR
>320 CALL SOUND(30,380,2)
>330 If Y<1 THEN 360
>340 IF Y>24 THEN 360
>350 GOlO 220
>360 YDIR=-YDIR
>370 CALL SOUND(30,380,2)
>3.'!0 GDTO 220
>RUN
--screen cLears
BALL COLOR? 5
SCREEN COLOR? 15
--baLL appears in center of
screen and begins bouncing
(press CLEAR to stop
the program)
I11-21