DosRealAvail()                Get total available real mode memory.
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 Function : Get total available real mode memory.

 Syntax   : USHORT BLXAPI DosRealAvail(PULONG bytesavail);

 bytesavail Pointer to a long integer to receive the number of bytes of
            available real mode memory.

 Return   : The total available real mode memory in bytes.

 DosRealAvail() returns the amount of real mode memory available which may be
 allocated with DosAllocRealSeg().

 Example:

    #include <stdio.h>
    #include <blx286.h>
    void main(void)
    {
    ULONG       vmfree, xmfree, rmfree ;
    if (DosVMAvail(&vmfree) == 0)
       printf("There are %08X bytes free virtual memory\n", vmfree);
    if (DosMemAvail(&xmfree) == 0)
       printf("There are %08X bytes free extended memory\n",    xmfree);
    if (DosRealAvail(&rmfree) == 0)
       printf("There are %08X bytes free real memory\n", rmfree);
    }