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Configuring Combo Coax/Twisted-Pair Network Adapters
Last updated: 2/2/02

Q.  How does one make a combo coax/twisted-pair network adapter that works in a thinwire coax network work in a twisted-pair network?

A.  Combo network adapters or Network Interface Cards (NICs) are designed to work with either 10BASE2 "thinwire" coax (http://duxcw.com/faq/network/10base25.htm) Ethernets or 10BASE-TX twisted-pair Ethernets.  They have coax connectors and RJ-45 jacks on the back of the card.  Most of these boards have one or more of four ways for configuring them to use one media interface or the other:

  • Some detect the media automatically.
  • Some have flash memory and the interface can be changed with a utility/diagnostic program that came with the NIC.
  • Others have a jumper(s) to change the media interface.
  • As I recall(?), some some of them can be changed in Windows.

You may be able to determine the manufacturer, etc. (http://duxcw.com/ faq/network/mac.htm and http://duxcw.com/digest/Fromshop/mb/det.htm) of the NIC and download the manual and software.

Another problem you ought to be aware of has to do with Windows and non-PnP (or those set to use a specific IRQ instead of Plug 'n Prey), Novell-compatible NE2000 NICs.  Many old combo NICs are NE2000-compatible.  The problem is that Windows 9X often insists on assigning IRQ 3 (http://duxcw.com/faq/irq/irq.htm) to a Novell-compatible adapter when the adapter is actually set for another IRQ. The fix is to determine what the real IRQ is and change it in Control Panel, System, Device Manager.  I usually (or used to) set non-PnP/ISA bus NICs to IRQ11, but that doesn't always work.

My advice...  When you upgrade from coax to twisted-pair, replace the NICs.  Good ones cost noticeably less than $20 each.

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