So I'm trying to detect through Visual Basic 6.0 when a voltage change occurs on one of the pins of the serial/parallel port. The whole thing is pretty simple; no data transfer/handshaking/etc ...

That's why laptops with a true RS232 serial port are at a premium for certain applications.<BR><BR>There are *some* USB-Serial bridges that are better than others.

The "serial" part of the serial port's name describes how data is transmitted one bit at a time in a single line or "series." There were also parallel ports on computers that sent multiple bits ...