🚀 go-pugleaf

[This article is also archived at
ftp://ftp.syd.dit.csiro.au/pub/ken/NIC/ne2000irqconvert.txt]

How to convert a jumpered NE2000 to use high IRQ lines

The original NE2000, and some clones, have jumpers for selecting
between IRQ 2,3,4 and 5.  IRQ 3 and 4 are useless because they are
generally taken by serial cards, on ATs and above IRQ 2 is the same as
IRQ 9 and sometimes already taken. This leaves only IRQ 5. And many
sound cards use it.  This is silly because the NE2000 is a 16 bit card
and has the AT extension. Why they didn't provide jumpers to use the
high IRQ lines I don't understand.  Not even the low IRQ 7 line is
provided.

With a bit of hardware hacking you can move IRQ 3 and 4 lines to IRQ 10
and 11, which are much more likely to be available on ATs and above.

This modification only works for jumpered cards, as far as I know. I
don't think jumperless cards need this modification since more IRQs are
available, but I don't have a jumperless card so I can't be sure.

Disclaimer: The information here is provided as is, with no warranty. I
have tried to make it as accurate and clear as possible but mistakes
are always possible.  I am not responsible for any consequences of your
following it. The modification described is quite small but you
should be comfortable with doing small hardware alterations. If not,
don't do it or get someone who is an expert to help. In other words, if
you blow up your PC, or burn down your house, I am not responsible.

IRQ 3 and 4 go to connector fingers B25 and B24 respectively. This is
on the copper side of the board. Counting back from the gap between the
connectors, they are the 7th and 8th fingers.

With an art knife or similar, cut the traces to the fingers.  Check
with an ohmmeter that the connection is indeed broken.

Get two short lengths of thin jumper wire and solder one end to the
trace that used to go to B25 and the other end to D3.  D3 is the third
finger counting from the gap. There should be no other traces ending at
D3. You can probably find a handy through hole for soldering the B25
end. On the D3 end it's a bit tricker. You need to solder to the gold
plated finger but use as little of it as possible so that any solder
bump doesn't interfere with the card going into the motherboard
connector. Make sure your iron has a small tip, is at the right
temperature, and use thin solder.  Do the same with the trace to B24
and finger D4.

Double check your work to check that you have used the right
connections, that you haven't shorted any other connections, that
everything is firm, etc.  Now the jumper for IRQ 3 selects IRQ 10 and
that for IRQ 4 selects IRQ 11. Put a sticker on the card explaining the
new situation or you may forget.

Put the NIC in a computer and check it with a packet driver under DOS
or a Linux OS with NE2000 support compiled in.

Then have fun with your computer system.

	Ken