Lets say you use the command output 378, 0
This tells the computer to send the address 378 the data 0. Since the parallel port is an 8 bit port the computer will set the bits as 0000 0000. Now lets say you sent the port the value “1” the port would change to 0000 0001. If you then sent the data 0 to the port the port would change back to 0000 0000. This is why I would recommend making data value “0” all off. What you really need to do first is design the hardware that will control the bulbs. Decide what value will control what bulb e.g “1” or 0000 0001 input will control bulb number 1. Think about it this way in electronic designing what comes first the hardware or the software?
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