This has been implemented with by following "Serial Communications in Win32" by Allen Denver (Microsoft Windows Developer Support). It is compiled (by BORLAND C++ 5.0) and working on Windows 95. It should be working on NT machine too. This software is aimed to interface with the serial device. My main purpose is for using this "dll" to interface with PowerBuilder 6.0. It should be use in other kind of compiler on Windows too.
For powerbuilder user, I strongly recommend to use the custom object for PowerBuilder which is the upgrade of this DLL. It gives more stability. I keep this page as the reference for people who would like to talk to serial port in C.