I'm planning to use some USB/Parallel cables as a cheap way to get some digital inputs and outputs for my robot (at $5 each... how can I resist). I'm just wondering.... What is the limit to the number of parallel ports you can have on a PC (using linux)?
I would also like to know... How exactly do you go about writing a bit? Do you simply connect the input pin to a ground pin, say using a resistor? The SPP uses TTL logic, how is this usually done?