What NIC card do I use for HP Designjet 500 plotter? -

Need to know which NIC card to use in the HP designjet Plotter. I have found a few online, but not sure which one actually fits it. I have limited access to the plotter itself, so am unable to locate any markings on it that would indicate which NIC card it uses.

About HP Designjet 500 plotter can be read in http://us-td-info-blog.blogspot.com/?q=HP%20Designjet%20500%20plotter