I'm slowly reading the book, Linux Device Drivers, 2nd edition. In the beginning, they mention that for the most part you don't have to have to try any of it out on any actual hardware, but that in chapters 8 and 9, you might need to solder a little bit of wire. The closest I found to an explanation was in Ch.9, p.253, where they say: "A short length of wire inserted into the appropriate holes in the parallel port connector on the back of your system will create this connection." By "this connection", they mean they want pins 9 and 10 to be connected. A few lines later, they write: "If you'd rather avoid soldering, but you do have a printer at hand, you can run the sample interrupt handler using a real printer, as shown later. Note, however, that the probing functions we are going to introduce depend on the jumper between pin 9 and pin 10 being in place, and you'll need it to experiment with probing using our code."
I believe that what they have in mind is not difficult, but I don't think they have described it adequately. I'm not sure what they want me to do in the way of soldering. Solder what to what? They have a pin diagram of the parallel port in Ch.8 but I just don't believe they want me to solder something to it.
Along the way, they mumble: "The simplest way to force the interface to generate interrupts (short of hooking up a printer to the port) is to connect pins 9 and 10 of the parallel connector." Maybe when they say "connector", they mean to obtain the kind of connector that plugs into the parallel port (just the connector, with nothing attached to it, i.e. no printer) and connect two pins on that plug by soldering a wire to both of them. And then the two pins on the parallel port get connected by plugging the connector into the port. And they just forgot to mention that there is supposed to be a plug that you are soldering the wire to?
Is that what they mean? In other words, when they wrote: "...the appropriate holes in the parallel port connector on the back of your system", they didn't mean the parallel port itself, and they didn't mean the connector that is already attached to any device already plugged into the parallel port of your computer; they meant a connector that ISN'T on the back of your system yet but which is meant to be plugged into it and which you first have to go out and purchase and solder the wire on it before plugging into the back of your system, after which it will then be on the back of your system.
Anyway, I just thought it was worth asking about it before burning up my computer...