Odwolanie do pamieci karty graficznej

program ZAD1;

uses crt, dos;

var
i,j:byte;

procedure show(c,k,x,y:byte);
var
y1:word;
p:^byte;
begin
delay(5);
y1:=(y-1)*160+2*x-2;
p:=ptr($B800,y1);
p^:=c;
p:=ptr($B800,y1+1);
if k<>0 then
   p^:=k
else p^:=$20;
end;

begin
clrscr;
for i:=1 to 25 do
    begin
    if (i mod 2 = 1) then
       begin
       show(200,i mod 16,1,i);
       for j:=2 to 79 do
           show(205,i mod 16,j,i);
       show(187,i mod 16,80,i);
       end;
    if (i mod 2 = 0) then
       begin
       show(188,i mod 16,80,i);
       for j:=79 downto 2 do
           show(205,i mod 16,j,i);
       show(201,i mod 16,1,i);
       end;
    end;
readln;
end.