Hi ,
Pc's know only 0's and 1's.
however as u want to control those switches it can be easily done with the Pc (provided the switch has only two states ON & OFF). PCs communicate with the external world thru ports. Your PC will have three ports
1.Parallel Port (25 pins that loooong one)
2.Serial Port (9 pins ,a bit smaller one)
3.USB port ( a small rectangular socket)
Of these three, the USB port is the fastest, however its the hardest one to implement in your custom device. Hence unless ur app dont need Tremoooooodus speed u can go for either of the first two. Each has its own advantages.
The serial port communication needs least wiring ( 5 wires max and is the most suitable for wireless commn where only one bit can be sent at a time ). However it is harder to implement.
The parallel port commn needs more wires but as u need to control only 4 switches the wiring can be reduced. It is also the easiest one to implement. However remember , its unsuitable for wireless applns.
Now after deciding which port to use just google for further info. Also contact me if u need any further info ( particularly if u r interested in implementing serial port using Mc, I can help u .)
The following links may help u.
http://electrosofts.com/parallel/index.html
http://www.epanorama.net/circuits/parallel_output.html
http://www.arcelect.com/rs232.htm
http://www.beyondlogic.org/serial/serial.htm
Raja
rajagopal87 <<<@>>>gmail+++com