Source : Free On-Line Dictionary of Computing

wirehead
     
         /wi:r'hed/ (Probably from SF slang for an electrical
        brain-stimulation addict) 1. A hardware hacker, especially one
        who concentrates on communications hardware.
     
        2. An expert in {local-area network}s.  A wirehead can be a
        network software wizard too, but will always have the ability
        to deal with network hardware, down to the smallest component.
        Wireheads are known for their ability to lash up an {Ethernet}
        {terminator} from spare resistors, for example.
     
        [{Jargon File}]
     
        (1995-02-28)