Try something like this:
ACLS
SPSET 0,0
X=199:Y=119
@LOOP
STICK OUT SX,SY
IF SY<0 THEN YVEL=-4*SY
Y=Y+YVEL:SPOFS 0,X,Y
YVEL=YVEL-0.25
IF Y>239 THEN Y=239
VSYNC 1
GOTO @LOOP
Anyone notice how much more powerful this is? The max array size is about 40000x40000. Compare that to the previous version, 512x512! It runs about x30 faster, too! This app is amazing. I loved PTC2!