Path: gmdzi!unido!mcsun!uunet!elroy.jpl.nasa.gov!decwrl!sgi!shinobu!odin!kahua.esd.sgi.com!paquin
From: paq...@kahua.esd.sgi.com (Tom Paquin)
Newsgroups: comp.sys.sgi
Subject: Re: invisible cursors on PIs
Keywords: cursors, PI, unofficial, unsupported
Message-ID: <1991Jul11.203944.11629@odin.corp.sgi.com>
Date: 11 Jul 91 20:39:44 GMT
References: <1991Jul10.064731.29662@nas.nasa.gov>
Sender: n...@odin.corp.sgi.com (Net News)
Organization: Silicon Graphics Inc.
Lines: 55

It is possible to get a two-color cursor on a PI.  It is not simple,
it is not low-risk, and it won't work for most existing PIs because
of system software issues.  It nukes warranties and bags support.

Of course, this is not a procedure endorsed or recommended by
Silicon Graphics.  But that's not the worst part.  I am fairly
sure that you'd have a tough time getting support for (allegedly)
unrelated problems if you call the hotline and say "I have
a PI, but I've soldered some of my own chips into it, but that
shouldn't matter and anyway, I have this other thing that isn't 
working."   I haven't read whatever agreement gets you hotline
support, but I think it likely that if you do this, you are
completely on your own.  I'm no authority on this.

The two-color cursor mod is entirely incompatible with pre-4.0 Irix.
Unless and until you get 4.0, you do NOT want to try this; the result
will be a machine which won't boot.  (Yes, there are intelligible
reasons for this.)

The mod requires soldering your graphics board.  One slip and you 
could waste your board.  This kind of failure is not, I believe,
covered by any sort of warranty.  (Did you buy your PI with AmEx?)

OK, so if you're crazy, not dissuaded, or merely curious:

0) Get used to the idea that if you screw this up, you're out at least 
   your graphics board and SGI isn't going to fix it for free.  Believe 
   that all your future support may have to come from comp.sys.sgi.
1) Make sure you're on Irix 4.0 (or later?).  If you're installing
   4.0 and doing the mod, you must do the 4.0 inst first.
2) Go to the store and buy a Brooktree chip which says Bt431KC on it.
3) Remove your E module.  This holds the CPU and graphics board.  
   Take the entire E module out of the PI chassis.  Then turn it
   graphics-side up and remove the faceplate.  You can tell graphics
   side from CPU side by looking at the connectors on the back.  If
   you need more help than that, you shouldn't try this.  Once you can
   see the graphics board, check for a Z buffer. If you have a Z buffer 
   installed, remove that.  Be careful, ground yourself, etc.
4) Locate through-holes for an absent chip labelled I8G6.  It's right
   next to an existing Bt431 kinda in the middle of the board,
   right next to the large Weitek chip.
5) Solder the new Bt431 in the I8G6 location, oriented the same
   way as the existing Bt431.  They'll be right next to each other.
   The through-holes should be filled with solder.  You'll probably
   have to empty them first.  Remember not to screw anything up with 
   that soldering iron.
6) Reinstall your Z-buffer if you had one, put the cover back on
   the e-module, reinstall the e-module, and boot.  Irix 4.0 will
   try to use the new chip.

-- 

		-Tom
*****
Opinions are mine, not SGI's.