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bdos

Usage

   #include <dos.h>
   int bdos(int func, unsigned DX, unsigned AL);

Description

   The bdos function calls a DOS function (int 21h) where func is the
   function number and DX and AL are the values to be loaded into the DX and
   AL registers prior to the function call. DOS function calls are used to
   access the facilities of the operating system. A list of system calls and
   their register requirements for MS-DOS can be found in the MS-DOS
   Technical Reference manual. Another good source of information is
   Advanced MS-DOS by Ray Duncan, published by Microsoft Press. Some system
   calls require registers other than DX and AL to be set up and therefore
   bdos cannot be used. In such cases use the intdos or intdosx functions.

   Under the X and P memory models bdos() and bdosx() carry out some
   filtering of parameters sent to the real mode interrupt. This enables
   MS-DOS functions running in real mode to access data stored in extended
   memory.

   Some of the available DOS functions are not supported or only partially
   supported in the X and P memory models, refer to the entry for int86()
   for more information.

Example 

   #include <dos.h>
   #include <stdlib.h>

   int main()
   {
       bdos(2,'C');        /* display the letter C */
       return EXIT_SUCCESS;
   }


Return Value

   Returns the value in AX after the system call.

See Also

   bdosx, intdos, intdosx, int86, int86x