Originally Posted by anroy
Does anyone know if there exist simple inexpensive hardware dummy devices to test input to and output from serial ports and parallel ports?
I have heard of something called breakout boards but was not really able to understand what they do. Would these be what I want?
For serial ports, the best things to use are, in no particular order: an oscilloscope (with capable operator), another serial port with a decent terminal emulator attached (C-Kermit is my strong preference), a breakout box, a DVM. For parallel ports, a DVM, and maybe some LEDs with appropriate limiting resistors attached. A pile of hardware documentation for either, much of which can be found online (although parallel port info is becoming scarcer by the day).
A breakout box is simply a small box, with D-Sub connectors on each side, so you can insert it between two serial devices. Usually it has switches or a jumpering system to allow you to connect the conductors of the two serial cables in arbitrary ways. They also usually have tri-color LEDs that can be used to see the states of the various signals in the RS-232 interface. 20 years ago every IT nerd had one of these beside his coffee cup; now I don't know where you'd buy one.
Are you planning to re-write the existing drivers for standard serial/parallel PC hardware, or are you going to use those devices as tools to exercise/monitor some other device for which you'll create a driver?