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From: taylorj@yvax.byu.edu
Newsgroups: comp.lang.pascal
Subject: re: Readkey without "use crt" (Was Re: Strobing the keyboard)
Message-ID: <922taylorj@yvax.byu.edu>
Date: 21 Nov 89 03:39:59 GMT
Lines: 38

There are two solutions to this problem:

1) Use CRT but make the I/O go through DOS.  All you have to do is add the
lines
  Assign(input, ''); reset(input);
  Assgign(output, ''); rewrite(output);
to the start of your program.  (TP 5.0 manual p.135)

2) Go directly to DOS or BIOS to read a key.
To read a key using DOS, you'll need something like
  var
    regs :registers;

  regs.ah := 8;
  msdos(regs);
  if regs.al = 0 then begin
    msdos(regs);
    {do whatever you want to recognize extended key codes}
  end;
  key = regs.al;

This can be redirected, so if you want to always read from the keyboard you
might want to use BIOS instead:

  regs.ah = 1;
  intr($16, regs);
  if regs.al > 0 then key := regs.al
  else begin
    key := regs.ah;
    {do whatever to recognize extended key codes}
  end;

Both of these wait until a character is pressed.  There are other calls to
check to see if a key has been pressed.


Jim Taylor
Microcomputer Support for Curriculum
Brigham Young University
taylorj@yvax.byu.edu