Subject: Ejecting CD-ROM

86. *****
 Q: How do I eject a CD-ROM using a Turbo Pascal program?

 A: The code for the ejection is given below. Note that it needs the
MSCDEXFN function from the previous FAQ item.
  uses Dos;
  {}
  procedure EJECT (charDev     : string;
                   var ok      : boolean;
                   var errCode : word);
  var regs        : registers;
      cdrom       : file;
      cdCtrlBlock : byte;            { CD-ROM Control Block }
      handle      : ^word;           { Handle referencing CD-ROM driver }
  begin
    Assign (cdrom, charDev);         { Character device for CD-ROM driver }
    {$I-} Reset (cdrom); {$I+}       { Tackle errors yourself }
    if IOresult <> 0 then begin      { Exit if file not found }
      ok := false;
      errCode := $FFFF;              { Your own arbitrary error code }
      exit;
    end;
    FillChar (regs, SizeOf(regs), 0);  { Just to make sure }
    regs.ax := $4403;                { Function $44, subfunction $03 }
    handle  := @cdrom;               { Establish the file handle }
    regs.bx := handle^;
    FillChar(CdCtrlBlock, SizeOf(CdCtrlBlock), 0);
    CdCtrlBlock := $00;              { $00 eject disk; $05 close tray }
    regs.ds := Seg(CdCtrlBlock);     { ds:dx CD-ROM control block }
    regs.dx := Ofs(CdCtrlBlock);
    MsDos (regs);                    { Call interrupt $21 }
    {$I-} Close (cdrom); {$I+}
    ok := regs.flags and FCarry = 0; { Success or not? }
    errCode := regs.ax;              { $01 = invalid function }
  end;                               { $05 = access denied }
  {}                                 { $06 = invalid handle }
  procedure TEST;                    { $0D = invalid data }
  var ok : boolean;
      code : word;
  begin
    EJECT ('K', ok, code);
    if ok then writeln ('Success') else writeln ('Error ', code);
  end;
  {}
  begin
    TEST;
  end.

My thanks are due to Miro Wikgren (wikgren@cc.helsinki.fi) who
pointed out that the "handle referencing character device for CD-ROM
driver" must be the name given when the CD-ROM driver is loaded in
CONFIG.SYS and AUTOEXEC.BAT. I could not solve this problem without
that help in comp.lang.pascal.borland. In fact the previous FAQ item
was tackled only after the current FAQ item had been solved first.

A slightly different approach to the file handle by Miro
  var cdrom : text; { CD-ROM is a character device }
  handle    : word; { Handle: word, not a pointer }
  :
  handle  := TextRec(cdrom).handle;  { Use TP help for more on this }
  regs.bx := handle;
  :

Another solution can be found in
 3427 Mar 15 18:35 ftp://garbo.uwasa.fi/pc/turbopas/cdtips01.zip
 cdtips01.zip Eject/Close/Lock/Unlock CD-ROM in TP for Win95, C.Rankin
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