PROGRAM lowres; {lores routine test}

{Copyright 1984 by N.T.Carnevale.
 Permission granted for nonprofit use.}

{$I PCP.INC}
{$I APLGR/G.INC}
{$I APLGR/L.INC}

VAR
  ans:char;        {for keyboard responses}
  scrn:integer;    {which lo-res graphics screen to use}
  h,v:integer;     {horizontal and vertical coordinates
                    --top left = 0,0}
  tint:loreshues;  {color used for drawing}

PROCEDURE delay;  {about 4 second delay}
VAR i,j:integer;
BEGIN
  FOR i:=0 TO 500 DO
    FOR j:=1 TO 500 DO;
END;

BEGIN
  lorespatch;   {install the register-loading routines}
  writeln('Low-resolution graphics exerciser');
  write('Press return to clear and fill screen 1: ');
  readln(ans);  {can't use lores screen 2}
  loresgr(1,FULLSCREEN);    {display lores screen 2}
  clear_lores_screen;       {clear it}
  tint:=BLACK;              {start with black}
  FOR v:=0 TO LOVRES-1 DO BEGIN
    setcolor(tint);         {use specified color}
    hlin(v,0,LOHRES-1);     {draw horiz line across screen}
    IF tint=WHITE THEN tint:=BLACK
    ELSE tint:=SUCC(tint);  {next color to use}
  END;
  delay;
  FOR h:=0 TO LOHRES-1 DO BEGIN
    setcolor(tint);
    vlin(h,0,LOVRES-1);  {draw vert line down screen}
    IF tint=WHITE THEN tint:=BLACK
    ELSE tint:=SUCC(tint);
  END;
  delay;
  textscreen(1);  {return to the text display before exit}
END.  {end of PROGRAM lowres}