In the April issue last year we published an article that showed how to program the serial port correctly under Windows. The methods described in that article appeared to be a bit too complex for many people. For this reason we wrote our own DLL, which can be used to simplify the programming of the serial port. This DLL will be described in this article.The serial port is still used by many electronics hobbyists to connect their computer to the outside world. This makes perfect sense, since such an interface is found on every standard PC and it also provides a few input and output signals as well as the serial communication channel. The USB port has these capabilities as well, but this requires some extra circuitry and many hobbyists would prefer to avoid that. In this context it’s better to keep quiet about ISA and PCI cards too. The serial port still remains the favourite solution when a simple connection is required between a PC and some electronics.