INT EC - Exact - RUNTIME INTERFACE MULTIPLEXOR
        AX = function number (0000h to 0140h)
        STACK:  DWORD address to return to
                any arguments required by function
Return: STACK:  return address popped, but otherwise unchanged
Notes:  this is the interface from applications to the runtime system by Exact
          Automatisering B.V. of the Netherlands.  By using this interrupt,
          it can provide DLL-style capabilities under MSDOS.
        the interrupt handler removes the return address and flags placed on
          the stack by the INT EC, then jumps to the appropriate function