chương trình:
uses crt, graph;
var a,b: smallint;
i,j,mx,my, x, y,xx,yy: uint16;
k: uint64;
c:string;
begin
clrscr;
a:=detect; b:=0; c:='';
initgraph(a,b,c);
mx:=getmaxx; my:=getmaxy;
for i:= 10 to mx-10 do
for j:= 10 to my-10 do
putpixel(i,j,white);
{setcolor(red);
rectangle(0,0,99,99)...