> SPIRAL :  M%=0 127 ( M% 2: < Find size of screen: F%'8;:W%=+1::H%=+1::+1=H%: PGx=W%*8:y=H%*(8-2*(3+6+7+11+14+17,M%)<>0 (H%=22 H%=25))) Z%:x=x*2:x>=&400::y=y*2:y>=&300 d: n Centre on screen: x y=y/2 x=x/2 r=y*7/8 l=8192/y : a = 0 x,y-r  % 0,(7): x + r*(a), y - r*(a) r=r-0.5 a=a+0.1 r45:W%2-23,H%-1);"There should be a spiral centred on the screen"; l W%<46:W%2-8,H%-4);"There should be a";W%2-8,H%-3);"spiral centred on";W%2-5,H%-2);"the screen";  (500)=8:M%=M%-2 " M%