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─────How to Build a Dual-Mode Program───────────────────────────────────────
 
     If you cannot create a bound program, you can create a dual-mode
     program instead. A dual-mode program is similar to a bound
     program. Both types of programs run in both real mode and
     protected mode, but they have different internal structures.
 
     A bound program has common executable code that runs in both
     modes. System calls are specific to real mode or protected mode,
     but all system calls are modified at load time.
 
     In contrast, a dual-mode program has two separate programs in one
     file. One of these programs runs in real mode, and the other runs
     in protected mode. All the code in a dual-mode executable program
     runs in one mode or the other.
 
     To create a dual-mode program:
 
       1. Link a real-mode version of your program.
 
       2. Create a module-definition file that contains the statement
 
               STUB filename
 
          where <filename> is the name of your real-mode program.
 
       3. Link the protected-mode version of your program with the
          module-definition file above. The protected-mode program and
          the real-mode program should have different names.
                                    -♦-