From: forrestc@lewis.mt.net (Forrest W. Christian)
Subject: IRQ conflict hack
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Date: Mon, 13 Apr 1998 08:22:31 GMT
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Every once in a while I do a hack which I just have to share with the
world.

ObIRQConflictWhichWon'tLetTheKeboardWorkFixHack:

Get this call from one of my co-workers which is installing a new WaveLan
card in a PC.   Can't get it to work.   Classic IRQ conflict symptoms.

So, after walking him through changing the IRQ over the phone (These cards
have jumpers for the IO Address and the IRQ is set in a EEPROM in the card
so you basically have to run a piece of software to change it), we start
playing with which IRQ's work.  10 doesn't, 11 doesn't, and lo and behold,
12, well, lets just say with 12, the Keyboard don't work any more.  (I
didn't figure this out until after we had set the second card to 12).

Now the hitch...  To change it off of 12 you have to run this software.
However, you can't run the software because the card is on IRQ 12 and the
keyboard don't work.  Catch 22.

So, I grab my trusty "Interfacing to the IBM PC" book, and a roll of
electrical tape and head off to the client site.   I considered Duct tape
for storytelling value but duct tape has that horrid (wonderful) adhesive
and I'm not too sure about it's electrical qualities.

Anyways, I get to the client site.   Pick up the card (after previously
checking the Interfacing Book) and tape over the appropriate card edge
finger for IRQ 12 and stick it in the machine.  Low and behold the
keyboard works and I can set the card to something other than IRQ12.
Shut down the machine, remove the tape, and configure the card to an
unused IRQ and everything is great.

The coworker was rather shocked.   Guess doing hardware card design pays
off once in a while.

Hmmm... kind of reminds me of the time that I used a spare inverter on a
card to change the IO address of the card....  but I've already used that
hack here, ol well.

-forrestc@imach.com