program iodemo(inp,output,infile,outfile);
type
    string15=packed array[1..15]of char;
    ptr63   =^string63;
    string63=packed array[0..63]of char;
    string31=packed array[1..31]of char;
var
    infile,outfile,inp:text;
procedure pprompt(s:string15);extern;
procedure pdefine(k:integer;p:ptr63);extern;

procedure define_files;
var filename:string31;length:integer;first_try,ok:boolean;

function get_name(prompt:string15;var l:integer;var name:string31):boolean;
var ok:boolean;temp:integer;
begin
if first_try then begin pprompt(prompt);reset(inp);first_try:=false;end
             else begin pprompt(prompt);while inp^=' ' do get(inp);end;
for l:=1 to 31 do name[l]:=' ';
l:=1;
while (inp^<>' ') and not(eoln(inp)) and (l<31) do begin
      name[l]:=inp^;get(inp);l:=l+1;end;
for l:=l downto 1 do 
      if ('a'<=name[l])and(name[l]<='z')then 
           name[l]:=chr(ord(name[l])-ord('a')+ord('A'));
l:=31;while (name[l]=' ') and (l>0) do l:=l-1;
ok:=(l>0)and(inp^=' ');
if not ok and (l>0) then writeln('Invalid filename ',name);
if not ok then while (inp^<>' ') and not(eof(inp)) do get(inp);
get_name:=ok;
end;{of get_name}

procedure call_pdefine(pas_len:integer;pas_file:string15;
                       emas_len:integer;emas_file:string31);
const magic=402653312;
var p63:ptr63;i,j:integer;param:string63;
begin
for i:=0 to 63 do param[i]:=' ';
for i:=1 to pas_len do param[i]:=pas_file[i];
param[i]:=',';j:=i;
for i:=1 to emas_len do param[i+j]:=emas_file[i];
{writeln('Command:pdefine',param);}
{writeln('len=',i+j-1:1);}
param[0]:=chr(i+j-1);
new(p63);
p63^:=param;
pdefine(magic,p63);
dispose(p63);
end;{of call_define}

begin {define_files}
first_try:=true;
writeln('Please give the name of the input file to be used:');
call_pdefine(3,'INP............',3,'.IN............................');
repeat; ok:=get_name('Input file:    ',length,filename);until ok;
call_pdefine(6,'INFILE.........',length,filename);
writeln('Please give the name of the output file to be used:');
repeat; ok:=get_name('Output file:   ',length,filename);until ok;
call_pdefine(7,'OUTFILE........',length,filename);
end;{ of define_files}

begin {main program}
writeln('This demonstration program shows how to avoid that "Data:" prompt');
writeln('that appears when you run a program. I askes for the names of two');
writeln('files and copies the input file to the output file               ');
writeln('File names must be no more than 31 characters long');
writeln;
define_files;
reset(infile);
rewrite(outfile);
while not eof(infile) do begin
   while not eoln(infile)do begin
      outfile^:=infile^;get(infile);put(outfile);
   end;
   writeln(outfile);
   if not eof(infile) then get(infile);
end;
end.