25.3 DoubleDOS

     Smart multi-tasking software allocates a virtual screen buffer
     for each task. Applications can then ask the multi-tasking
     software where it should write and the multi-tasker handles the
     screen updates. DoubleDOS 5.0, however, is using a different
     method.

     Every time you switch tasks from the keyboard, the screen-buffers
     change. So there is no easy way for the software running under
     DoubleDOS to detect this. In DoubleDOS 5.00, there are two
     options that allows you to run FrontDoor under DoubleDOS just
     fine. You MUST run FrontDoor in the TOP section for the two
     methods below to work.

     DISPLAY=TEXT        If your system has a MCGA, CGA, EGA or VGA
                         card installed, there is extra memory
                         available on those cards for graphics, etc.
                         DoubleDOS can use some of that memory for
                         each of its screen buffers. To enable this,
                         add DISPLAY=TEXT to your DDCONFIG.SYS file.

     REFRESH             If you have a text-only adapter (MDA) there
                         is most likely no extra memory available on
                         the card. Add REFRESH by itself on a line to
                         your DDCONFIG.SYS file. This will tell
                         DoubleDOS to repaint the screen if the other
                         task is bleeding through.

     X00 and DoubleDOS   When using FrontDoor, X00.SYS and DoubleDOS,
                         do not assign the COM ports in DDCONFIG.SYS.
                         If you have problems with your clock, try the
                         DEFER option in X00.

     Make sure you replace ANSI.SYS with DBLDANSI.SYS.

     The BOTTOM partition should initialize before the TOP partition.
     In other words, if you are loading FrontDoor in the BOTTOM
     partition, try to delay the initialization of the TOP partition.