Pascal/Turbo Pascal - como emular bsave y bload de gwbasic en turbo pascal?

program ScrnSaveLoad;

uses graph;

TYPE STR255=STRING[255];

VAR CH:CHAR;

var i : integer;

procedure scrnsave (fname:str255;length:integer);

var

buffer:byte absolute $b800:$0000;

filevar:file;

begin

assign (filevar,fname);

rewrite (filevar,length);

blockwrite (filevar,buffer,1);

close(filevar);

end;

procedure scrnload (fname,str255;length:integer);

var buffer:byte absolute $b800:$0000;

filevar:file;

begin

assign (filevar,fname);

reset (filevar,length);

blockwrite (filevar,buffer,1);

close(filevar);

end;

begin

graphcolormode;

for i:=19 downto 1 do

circle(160,100,5*i,1+i mod 3);

scrnsave ('screen.dat',16000);

repeat until keypressed;read(kbd,ch);

graphcolormode;

scrnload('screen.dat',16000);

repeat until keypressed;read(kbd,ch);

textmode(c80);

END.