100 cls 3
110 h = 639:v=479:u=40:w=40
120 line 0,v/2,h,v/2
130 line h/2,0,h/2,v
140 x=-8:gosub 1000
150 FOR i=-8 TO 8 STEP 1
160  x=i
170  p1 = p : q1 = q
180  gosub 1000
190  line p1,q1,p,q
200 next i
210 end
1000 y=2*x*x - 3*x+1
1010 p = h/2+x*u:q= v/2-y*w
1020 return