SGI: Hardware

Personal iris dual color cursor hack

jan-jaap
Donor
From Wijchen, The Netherlands
Who joined June 17, 2004, 11:35 a.m.

Wrote the following at March 26, 2009, 3:55 p.m...

I've always been intrigued by this section in the old "This old SGI" FAQ:

This Old SGI wrote: The Mysterious Cursor Hardware Hack

A number of early posts refer to a hardware hack that was apparently popular within SGI itself, and which made it possible to have a two-color hardware-supported cursor on the PI. I am not currently aware of what added value this modification actually has, but I'll include it here for anyone who wishes to experiment. The gist of the modification is the addition of a Brooktree chip (Bt431KC) to the GR1.x Graphics board. If you remove the GR1.x board, you will notice an empty IC location (I8G6) next to the a Bt431KC which is already on the board. You simply install a second Bt431KC in this location. Note that the IC pads at this location will be filled with solder, so you'll have to CAREFULLY remove the excess solder from each pad hole. If I were you, I'd strongly consider using an IC socket, if the board clearance allows it. I have NOT tried this modification myself, nor have I been able to locate a source for spare Bt431KC chips. Apparently, IRIX versions 4 and above detected the extra hardware cursor support and could make use of it. I don't know if IRIX 5.x retained this support.

Recently I was able to obtain two Bt431KC chips and I decided to put this myth to the test

: The mysterious empty IC location (I8G6)

: Enough to modify two Personal Irises

: Carefully removed excess solder from each pad hole

: Bt431KC installed

: Victory!

IT WORKS!

As you can see in the last screenshot, 'gfxinfo' recognizes it, and I actually have a dual color cursor! This is IRIX 4.0.5 running on an IP10 (4D/25).

Even though the Bt431KC is in a socket, there is enough clearance to install the Z buffer board again.

As the Mythbusters would say: Myth confirmed 8-)

EDIT: the paragraph in "This Old SGI" is probably based on this message: http://groups.google.com/group/comp.sys ... e919cd89be
Good thing I installed the second Bt431KC in a socket, I don't want to loose the option of running 3.3 on this box.

Now this is a deep dark secret, so everybody keep it quiet

It turns out that when reset, the WD33C93 defaults to a SCSI ID of 0, and it was simpler to leave it that way... -- Dave Olson, in comp.sys.sgi
Currently in commercial service:

(2x)

In the museum : almost every MIPS/IRIX system.
Wanted : GM1 board for Professional Series GT graphics (030-0076-003, 030-0076-004)

pentium
From Kamloops, BC
Who joined Aug. 28, 2006, 6:29 p.m.

Wrote the following at March 26, 2009, 5:02 p.m...

So what exactly does this actually do and what is your source for these Bt431KC chips?

<-------- A very happy forum member.

AndrewR
From Saint-Petersburg, Russia
Who joined Aug. 23, 2008, 8:36 p.m.

Wrote the following at March 26, 2009, 5:34 p.m...

Very nice, thanks for pictures!

D-EJ915
From Virginia Beach, USA
Who joined July 30, 2007, 10:07 p.m.

Wrote the following at March 26, 2009, 5:35 p.m...

Haha that's cool, what colour is the cursor normally? Plain red?

SAQ
From Renton, WA
Who joined July 19, 2006, 8:37 a.m.

Wrote the following at March 26, 2009, 5:45 p.m...

plain red.

I might need to give that a try. Pity it wasn't standard.

"Brakes??? What Brakes???"

:Indigo:

(single-CM)

jan-jaap
Donor
From Wijchen, The Netherlands
Who joined June 17, 2004, 11:35 a.m.

Wrote the following at March 27, 2009, 2:29 a.m...

pentium wrote: So what exactly does this actually do

It gives you two cursor planes. In other words, it gives you a tiny white border around the normally solid red mouse cursor.

pentium wrote: and what is your source for these Bt431KC chips?

eBay. Searching online is useless because you quickly get lost in the world of chip brokers etc.

I probably spent 10 EUR on this hack, which may be a lot to get a tiny white line around a mouse cursor, but not much for a fun evening

Now this is a deep dark secret, so everybody keep it quiet

It turns out that when reset, the WD33C93 defaults to a SCSI ID of 0, and it was simpler to leave it that way... -- Dave Olson, in comp.sys.sgi
Currently in commercial service:

(2x)

In the museum : almost every MIPS/IRIX system.
Wanted : GM1 board for Professional Series GT graphics (030-0076-003, 030-0076-004)

nekonoko
Site Admin
From Pleasanton, California
Who joined Jan. 23, 2003, 1:31 a.m.

Wrote the following at March 27, 2009, 2:39 a.m...

So it basically updates the mouse pointer to the same scheme the more modern IRIX hardware uses - that's pretty neat!

I'm on the lookout for some chips as well; I have one I can probably salvage from a dead board, but I'd like to update all three of my working boards at some point.

Twitter: @neko_no_ko
IRIX Release 4.0.5 IP12 Version 06151813 System V
Copyright 1987-1992 Silicon Graphics, Inc.
All Rights Reserved.

jan-jaap
Donor
From Wijchen, The Netherlands
Who joined June 17, 2004, 11:35 a.m.

Wrote the following at March 27, 2009, 2:45 a.m...

nekonoko wrote: I'd like to update all three of my working boards at some point.

Keep in mind that the original message in the usenet archives claims this will prevent IRIX 3.3 from booting. I would at least install it in a socket.

Now this is a deep dark secret, so everybody keep it quiet

It turns out that when reset, the WD33C93 defaults to a SCSI ID of 0, and it was simpler to leave it that way... -- Dave Olson, in comp.sys.sgi
Currently in commercial service:

(2x)

In the museum : almost every MIPS/IRIX system.
Wanted : GM1 board for Professional Series GT graphics (030-0076-003, 030-0076-004)

nekonoko
Site Admin
From Pleasanton, California
Who joined Jan. 23, 2003, 1:31 a.m.

Wrote the following at March 27, 2009, 2:47 a.m...

Oh definitely - I rarely install chips directly on a board unless I can't avoid it (clearance issues or some such).

Twitter: @neko_no_ko
IRIX Release 4.0.5 IP12 Version 06151813 System V
Copyright 1987-1992 Silicon Graphics, Inc.
All Rights Reserved.

fzalfa
From avignon ,provence, france
Who joined June 19, 2005, 11:38 a.m.

Wrote the following at March 27, 2009, 4:35 a.m...

cool !!!

this feature won"t work with irix 3.x ??

Laurent

SGI or die !!!
:O2:

HP proliant DL 585 Quad Opteron dual core 2.5Ghz 16Gb

PymbleSoftware
From P.O. Box 529, Gordon, Sydney, NSW 2072, Australia.
Who joined July 15, 2008, 5:48 p.m.

Wrote the following at March 27, 2009, 6:23 a.m...

Very cool hack.

I could ask someone about Bt431KC chips. I have preferred access to some chip brokers in various parts of Asia who claim that they can get anything even Russian ex-military chips (supposedly high spec, extreme operating temps, etc).
I'll have to dig out some business cards. Or wait until I go back in June.

Regan

死の神はりんごだけ食べる

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nekonoko
Site Admin
From Pleasanton, California
Who joined Jan. 23, 2003, 1:31 a.m.

Wrote the following at March 28, 2009, 5:39 p.m...

fzalfa wrote: this feature won"t work with irix 3.x ??

Apparently. This the original Usenet post which outlines the installation procedure and lack of 3.x support:

http://groups.google.com/group/comp.sys ... e919cd89be

Tom Paquin Jul 12 1991, 4:20 am wrote: 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.

nekonoko
Site Admin
From Pleasanton, California
Who joined Jan. 23, 2003, 1:31 a.m.

Wrote the following at April 13, 2011, 2:17 p.m...

If anyone is looking to do this hack, there are a couple of the BT431KC chips currently available on eBay. I already bought and received two from the seller for my own use:

http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... 0619029119

It took two years to get any eBay hits on BT431KC (I created the search right after jan-jaap started this thread), so grab them while you can

smj
From Berkeley, CA, USA, NA, Earth, Sol
Who joined Nov. 12, 2007, 7:54 p.m.

Wrote the following at April 14, 2011, 12:50 a.m...

Love this kind of thing, if I had a PI I'd be chasing that auction.

Then?

... Now?

+MLA

... Other: DEC :BA213:

Sun , DG AViiON , NeXT :Cube:

jan-jaap
Donor
From Wijchen, The Netherlands
Who joined June 17, 2004, 11:35 a.m.

Wrote the following at April 14, 2011, 1:18 a.m...

nekonoko wrote: It took two years to get any eBay hits on BT431KC (I created the search right after jan-jaap started this thread), so grab them while you can

Wow, these things are rarer than a good Tezro :shock:

. I must have been extremely lucky, or (more likely) the chips I bought simply had been sitting on eBay for ages.

Here's a better zoom of the empty socket:

Good luck!

Now this is a deep dark secret, so everybody keep it quiet

It turns out that when reset, the WD33C93 defaults to a SCSI ID of 0, and it was simpler to leave it that way... -- Dave Olson, in comp.sys.sgi
Currently in commercial service:

(2x)

In the museum : almost every MIPS/IRIX system.
Wanted : GM1 board for Professional Series GT graphics (030-0076-003, 030-0076-004)