procedure textmode; external $901f; procedure graphmode; external $9010; procedure plot (x,y,c:integer); external $901C; procedure graphbackground (c:integer); external $9019; procedure textcolor (c:integer); external $9016; procedure textbackground (c:integer); external $9022; function wherex:integer; external $9025; function wherey:integer; external $9028; procedure draw (x,y,x1,y1,c:integer); external $902e; procedure circle (x,y,r,c:integer); external $9013; procedure fillscreen (c:integer); external $904c; procedure gotoxy(x,y:integer); external $902b; procedure clrscr; external $9031; procedure sound (f:integer); external $903a; procedure nosound; external $903d; function hi(c:integer):integer; external $9040; function lo(c:integer):integer; external $9043; function swap(c:integer):integer; external $9046; function keypressed:boolean; external $9049; procedure fillshape(x,y,c:integer); external $9037; function getdotcolor(x,y:integer):integer; external $9034; ¾