hardware interfacing in c
Dear Kotis, well you can interface any device using parallel port the only thing you need to have is a NPN Transistor, just conenct the base of the transistor to the Data Pin of the parallel port and then connect a relay to the emitter of and provide a vcc to the collector, the relay will be connected to your device which will be operational when the transistor is switched on, there are 8 Data Pins thus you k connect upto 8 Bits of Devices that is at most 255 Devices and control them simultaneously...the control command syntax for c/c++ is
outport(0x378,a);
here 0x378 is the parallel ports address and 'a' is a variable depending on the value data pins of the parallel port will by high/low, thus operating the specific transistor/device,...
Best Regards
Jamshid Dastur