CLG
y=125
do
color white
rect 100,50,151,151
color black
text 30,110,"VOLTAGE"
text 45,95,"   ^"
text 45,125,"   v"
text 151,205,"< TIME >"
for  x=100 to 250
r=rand*100
if r>50 then y=y+1
if r<50 then y=y-1
if y>200 then y=200
if y<50 then y=50
plot x,y
next x
until false