The Silicon Graphics IRIS Indigo is a UNIX workstation, used principly for 3D graphics, manufactured between 1991 and 1994. For its time, it had unparalleled graphics performance for a desktop workstation. Its practical uses as a graphical workstation have long-since been eclipsed by bargain-basement PCs, and technologically, the Indigo has been left in the dust. For regular use, however, the Indigo is still very capable, and it's become very popular among computer hobbyists, even for everyday use. Plus it's the spiffiest-looking computer you can buy for less than the cost of a good meal.

The Indigo is a cool computer for a number of reasons. Some of these reasons have gotten less-cool over time, but they're still compelling enough to attract people more than a decade after its prime. Among them:

• Its top-of-the-line graphics can provide 24-bit color at 1280x1024, and can animate 3D wireframe and solid-color models, with fog, lighting and transparency effects, at up to 30 fps (even at full screen).
• It has built-in CD-quality stereo sound, with a bi-directional digital audio port that supports AES and S/PDIF encoding. When coupled with an ArDAT Python 4320 DAT drive, you can get DAT audio over SCSI.
• The hardware is easily accessible; the motherboard and graphics subsystems just pop right out, and the internal drives are sled-mounted, which make them a breeze to install or remove.
• The Indigo runs a variant of UNIX (called IRIX), so it's nice and stable, and you can get a lot of work done at once, even with a (relatively) slow processor.
• Experts agree, the Indigo's most charming quality is its spiffy blue case.

It's old. The Indigo is old enough to register to vote, or even rent a truck. While this computer helped pioneer the graphics industry with films like "Terminator 2" and "Jurassic Park", it's been long-extinct in the field.

• The fastest processor it can have is more than an order of magnitude slower than a garden-variety Pentium-4.
• The 3D graphics hardware doesn't have texture memory, and consumer-level PCI/AGP/PCI-X graphics cards have been crushing it like a bug since the turn of the century.
• The serial ports have a maximum throughput of 38,400 bps, which makes ISDN and other high-speed communication impossible, and the internal networking is limited to 10baseT. (Although it can be upgraded with various high-speed networking options (FDDI/ATM/100baseT), if you can find them).
• The hardware runs pretty hot and lets off an odious (but not uncomfortable) amount of heat.
• And that spiffy blue case is, by today's standards, pretty large and heavy.

Being old, and having been built by a company that produced lots of large computers based on the VME architecture, the Indigo itself is modeled after a VME machine, but scaled down. This gives it a fundamental architecture that most people regard as being atypical for a computer. That is, it doesn't have a motherboard, per se. Instead, it has a backplane; two subsystems mount to the backplane (which are the "CPU" and "Graphics" subsystems), as do the internal and external drives and the power supply.

Much like a VME system, the subsystems are installed in a mini card cage, and the drives are installed a mini drive vault, with three drive bays.

The CPU subsystem has -- of course -- the CPU, and sockets for RAM and the clock battery ("TOD battery"), plus user-non-installable bits like the cache, and audio and serial controllers.

The graphics subsystem (a.k.a. GPU) comes in different flavors, and occasionally has lots of arcane parts attached to it. These parts will determine (1) what size of monitor your Indigo can support, in terms of resolution, (2) how many colors it can display, (3) its 3-D performance, and (4) what kind of video systems it can support.

Each of these components are discussed in greater detail elsewhere on this page, starting with ...

The SGI Indigo will typically have either:

• A MIPS R3000 processor at 33MHz (a.k.a. the "R3000 Indigo")
• A MIPS R4000 processor at 100MHz (a.k.a. the "R4k Indigo")

Note that it is possible to upgrade the R4k Indigo with a 150MHz R4400 processor. This is a very simple upgrade, and will increase your computer's performance by about 30%.

Word of note: The R3000 and R4k Indigos are fundamentally different machines. They look alike on the outside, but on the inside, they have little in common. The downside is that it's impossible to upgrade from the R3000 Indigo to the R4k Indigo without swapping out the entire motherboard and power supply. (And, by some accounts, the NVRAM in the backplane.) The easiest (and cheapest, and most trouble-free) way to perform this upgrade is to obtain an entirely new system. Keep this in mind if you ever plan on getting an Indigo.

As the R3000 and R4000 machines have fundamentally different architectures, this is reflected in the types of RAM they use.

• The R3000 can have up to 96MB of RAM (with bizarro SGI proprietary SIMMs (64 pin w/ASIC, parity), which are increasingly difficult to find).
• The R4k Indigo can have a maximum of 384MB, and they conveniently use the (relatively) common 72-pin SIMMs, with page-mode parity.

Word of note: There is a bug in the R3000 Indigo that allows it to only have one set of four 4MB SIMMs. If you install two or more sets of 4MB SIMMs, the computer will not work. From the SGI hardware FAQ: "Due to a design flaw, only one set of 4MB SIMMs (16 MB per bank) can be used in an R3000 Indigo, 4D/30 and 4D/35. This limitation doesn't apply to the 2 MB or 8 MB SIMMs."

Additional word of note: In R4k Indigos, if you have one or more sets of 16MB or 32MB SIMMs installed, you may see a warning during booting along the lines of: "Warning: Revision C Memory Controller (MC) chip needed in order to properly operate with SIMMS of this type." (The actual wording depends on your version of IRIX.) This warning is in place because of poor RAM SIMMs that were being sold by vendors at the time, and not all Indigos have Rev. C memory controllers. This isn't an exigent problem; as long as you can see all the RAM once the boot process has finished (say, with the hinv command), then the warning can be ignored.

The Indigo has the following graphics subsystem (GPU) configurations available:

• Entry Graphics (a.k.a. "Starter Graphics"): 8-bit color, soft-Z, no hardware acceleration, 1024x768 resolution;
• Express Graphics: some hardware acceleration, 1280x1024 resolution;
  • XS: 8-bit color, no Z, one geometry engine;
  • XS-24: 24-bit color, no Z, one geometry engine;
  • XS-24Z: 24-bit color, hardware Z-buffer, one geometry engine;
  • XZ: 24-bit color, hardware Z-buffer, two geometry engines;
  • Elan: 24-bit color, hardware Z-buffer, four geometry engines.

Both Entry Graphics and Express Graphics boardsets have a 13W3 port for "workstation monitors". Additionally, the Entry Graphics configuration also has an HD15 VGA port, so almost any old VGA monitor will work with it. Instead of VGA, the Express Graphics options have a "3-D" port, for you to attach a pair of stereo-vision goggles, and a BNC Genlock port, for synching up with external video components.

(FYI, some rare Express Graphics boards have two BNC Genlock ports, labelled "Genlock in" and "Genlock out". These boards are so rare I almost decided against mentioning this, but it's my goal to be comprehensive.)

The Indigo's 13W3 port expects a sync-on-green signal. This is important if you want to use a 13W3-to-HD15 converter/cable to connect your Indigo with a VGA monitor. Why? Because the monitor will need to be able to sync on the green signal as well if they're going to work together. Most modern VGA monitors will do this.

Word of note: You can freely upgrade from one GPU to another, but you will need to reinstall the OS to get it running properly. (Technically, some systems with Entry Graphics have issues with the boot EPROM that prevent it from upgrading at all, but that's another issue.) Also, the graphics hardware itself can be difficult to find. Typically -- as with the processor -- the easiest way to upgrade the graphics is to buy an entirely new system.

The Indigo uses a proprietary keyboard and mouse. There's not much more to say about this.

Actually, there's quite a bit more to say about this. The keyboards/mice used by the Indigo are same keyboards/mice that are used by the Crimson and Onyx. And yeah, that keyboard port looks like it's PS/2, but it's not.

I know what you're thinking. Don't go there.

Do not plug a PS/2 keyboard into the keyboard port! It's a trap!

I'm not exaggerating. If you connect a PS/2 keyboard to an Indigo, only one of them will survive.

While the next generation of SGIs (Indy, Indigo2, etc.) used the commonly available "PS/2 compatible" keyboards and mice -- and the newest ones have USB ports -- these original Indigos do not. Your only solutions are:

The Indigo has one narrow SCSI bus. There is a 50-pin Centronics port for external SCSI devices and three internal drive slots, (3.5", full-height), which typically hold hard disks, floppy drives, or 4mm DAT drives. The internal drive bays require a drive to be mounted on a "sled", which facilitates easy installation and removal. Unfortunately, these sleds can be difficult to find (outside of eBay, that is) and can be more expensive than an external drive case.

A few random notes about the Indigo's SCSI bus and drives:

• The SCSI bus itself takes ID=0. The system drive is typically ID=1, and is typically installed in the bottom-most drive bay, although these aren't critical. The internal drive bays are terminated, but any devices attached to the external SCSI port require termination.
• The original hard drives from SGI, when installed on the original sleds, will auto-select for SCSI ID based on the drive bay in which it is installed. (Bottom=1, middle=2, top=3.) You can get around this by jumping the drives yourself, if you feel so inclined.
• To my knowledge, pretty much any narrow 50-pin SCSI hard drive will work, although if you want to install it internally, you'll need a drive sled. If you don't mind having your hard drive in an external case, you can play the field, which includes IDE hard drives, using IDE-to-SCSI adaptors.
• The internal drive bays can house both 3.5" "slimline" and "half-height" hard drives, and there is enough room on the sled for an SCA-to-SCSI adaptor, if you want to use an SCA drive in your Indigo.
• (I've seen cute hacks where two slimline drives are double-stacked into a single bay, and while it works, it's a tight fit and I don't recommend it. I suspect the heat generated by two drives in such a small space could compromise reliability over the long-term.)
• The Indigo can talk to most SCSI CD-ROM drives, if all you want to do is to read data. For installing system software, you'll need a CD-ROM drive that is "SGI bootable" (this is a big deal). Also, some CD-ROM drives allow audio over SCSI, for playing audio CDs; otherwise you'll need to use the headphone jack, or jump the CD-ROM's audio-out ports with the Indigo's audio-in port (this is not a big deal).
• The original internal SCSI floppy drive released by SGI is notoriously prone to failure. Keep this in mind when buying one used.
• Not only will the SGI-released Insite SCSI "floptical" drive (created for the Indigo2) work just fine in the Indigo, (1) it can use 20MB floptical disks (although they're excruciatingly slow), (2) it looks great in the Indigo with its black bezel, and (3) it seems to be much more enduring then the original SGI floppy drive.
• Practically any old SCSI 3.5" DAT drive will fit in and work in the Indigo, but the original ArDAT Python 4320 DAT drive released by SGI is unique in that it allows you to play audio over the SCSI bus. This is a neat feature if you're into audio.
• Other popular removable-media formats can work fine with the Indigo, especially in IRIX 6.2 and later; IRIX's removable media demon (mediad) can automatically recognize (depending on your IRIX version): Iomega Jaz and Zip drives; various Syquest drives; various tape drives, from QIC to DLT; LS-120 "superfloppy" drives; and various magneto-optical drives. All in various filesystem types.

The Indigo also has:

• two serial ports (DIN8, as per the pre-USB Macintosh), with a maximum throughput of 38,400 bps each;
• an AUI networking port, for 10baseT networking;
• five audio ports (line-in, line-out, microphone-in, headphone-out, and bi-directional digital audio);
• a 25-pin parallel port, for printers and other sundry peripherals;
• whatever ports are provided by the graphics subsystem.

There are no VME, SBUS, PCI, or other common expansion slots on an Indigo. There are, however, two "GIO32" slots on the motherboard for nifty, hard-to-find expansion boards, such as SCSI and network cards from SGI, and other 3rd-party devices.

I really envy hobbyists that work with older Sun workstations. They can't walk through twenty feet of a computer flea market without tripping over a bazillion different SBUS option cards, from SCSI to ethernet to multi-serial controllers to fancy-pants audio processors. Those old Suns are quite expandable and the cards are not difficult to find. Trivial, in some cases. You might even be able to find one underneath your couch.

With SGIs, I'm afraid, this is absolutely not the case. The field is much more limited, and most of these options are quite uncommon.

Some cards take one GIO32 slot, while others require both of them. Although technically, the dual-slot cards don't actually plug into both GIO32 slots; their board-size just needs the space.

To my knowledge, you can find:

• SCSI-bus card (one slot);
• 10baseT networking card (one slot, with AUI port);
• Token-ring networking card (two slots, I think);
• FDDI card (available as both SAS and DAS, both take two slots; SAS has one dual-channel fibre port; DAS has two dual-channel fibre ports, with optical bypass switch (OBS) port));
• Various third-party ATM cards;
• Cosmo Compress card (one slot, requires Galileo Video board and R4k Indigo, and wacky cable; performs JPEG compression in hardware);
• Chyron Centaur video card (two slots, requires propetary software and wacky cables);
• Colorbus Cyclone RIP (raster image processor, for interfacing to a color copier/printer) (one slot).

Word of note: The architecture behind the GIO32 bus differs slightly between the R3000 and the R4k Indigos. Some early expansion boards may not work for the R4k Indigo, and similarly, some later expansion boards may not work for the R3000 Indigo.

While I haven't tried it myself, the use of non-Indigo GIO32 cards in the Indigo appears to be commonplace. These are GIO32 cards that were originally made for the SGI Indy and Challenge S, so they won't have the same precise form-factor, but they'll fit and some of them will even work.

These cards include the Indy/Challenge Cosmo Compress board, FDDI board, and the Phobos G130 and Set Engineering 100mbit network cards. These latter two cards are the only way to get 100baseT into your Indigo, so this backwards compatibility is a blessing. Though I should point out that your results will certainly vary, both by card and your version of IRIX.

The Indigo does not support video by default, only through add-on technogizmos.

The Indigo runs a variant of UNIX, developed at SGI, called IRIX. This is not something you can buy at a store or download for free. To install this operating system you will need the installation CD (or tape, for older versions).

For UNIX-heads, IRIX started as an SVR2 platform with BSD and SGI extensions that crept in over time. Today it is compliant with UNIX SVR4, POSIX and UNIX 95.

Regarding IRIX versions:

• The R3000 Indigo can only run IRIX 5.3 and earlier.
• The R4k Indigo, however:
  • can run IRIX 5.3 and later;
  • is typically found running IRIX 6.2 and later;
  • can accomodate IRIX 6.5 up through IRIX 6.5.22 (which is the last version to support the R4x00 processor).

SGI officially released IRIX 6.5.22 in Q3 2003; the Indigo has been an orphan ever since.

The technical answer is "yes", although for all practical purposes, IRIX is the only game in town.

It's a complicated story, but I'll hash it out the best that I can.

Like most commercial UNIX packages, the take-home message is that IRIX by itself does not come with a compiler. Some versions of IRIX are more friendly at supporting compilers than others. So here's the scoop, to the best of my understanding:

How much change is in your pocket?

Ho ho ho, I crack myself up. But really: the used market of today is much more forgiving than the value-added-reseller market of yesteryear. (At least, from the point of view of us hobbyists.) On Dec. 1, 1992, the R4k Indigo Elan retailed from SGI for US$32,000. As I write this, that very computer will frequently go unsold on eBay, with a starting bid of US$0.99, simply because the shipping costs will eclipse the unit's so-called "value".

The moral of the story: the value of older SGIs has hit that abyssal point: where you'll spend less money buying one up-front than you will when you drop it off later at the computer recycling center. If you keep your ear to the ground, you'll probably find an Indigo for free. Maybe even a whole pallet of them.

Personal reminiscence: I bought my first SGI, as a hobbyist, in March 1996. It was an R3000 Indigo with entry graphics, and it cost US$2000 (a fair price at the time). In May 2004 -- eight years later -- I posted a message in two different groups on usenet: "Free R3000 SGI Indigos: pick em up at my house and they're yours!" And no one responded. The computers were eventually hauled away by someone who had come to claim some of my Sun gear, and simply figured, "Sure, why not, they're free."

Probably not. SGI allowed other companies to OEM the Indigo, so there are a few rebadged variants out there. The hardware is identical, they even run IRIX, but the skins have no SGI Indigo logos to be found. Common rebadged Indigos include Control Data, Colorbus, and Siemens Nixdorf (with the latter unit, the computer case is dark grey).

Darn-tootin! While it might not be ideal for all the world's end users, the Indigo is a way-cool computer for the enthusiast who yearns to leave all Microsoft products behind and isn't afraid to hand-edit a configuration file with vi. The fact that it runs UNIX gives it a tremendous advantage: while the Indigo might not be terribly fast, UNIX gives it a lot of torque.

The user base for the SGI Indigo (and IRIX in general) is larger than you might think, and helpful support can be found, if you ask nicely, in the comp.sys.sgi.* newsgroups.

Software is freely downloadable from every corner of the globe, ranging from CDRW drivers to Quake3. And since SGIs have a niche popularity in the workstation world, it's usually pretty easy to build software for IRIX or find binaries.

If you are looking to get into UNIX for the first time, then you might find Linux to be a better learning platform, since it has better support and software availability. But in many regards, IRIX has always been one of the more innovative UNIXes out there, and the Indigo is a very fun computer to run it on.

When you consider the fact that this computer was released at the dawn of the 1990s, that it predates the web, multimedia, CD-ROM technology ... I challenge you to find a computer of a similar vintage that can fare, in a modern computing environment, with as much vim and vigor as the Indigo.

Word of note: Software availability for IRIX 5.3 is getting scarce, so the R3000 Indigo is, tragically, showing its age. Much of the software you find around the Internet, available for download, only have binaries or builds that will work with IRIX 6.x. So if you intend to get an R3000 Indigo, you'd better become good friends with the compiler. This is yet another reason why many people find the R4k Indigo to be a more-useful machine than its R3000 predecessor.

No, not at all!

The major fault of the Indigo is its age, and unfortunately, the technology behind the R3000 is older than that of its R4k sibling. For everything a technohobbyist needs out of a cool, decades-old computer, the R3000 delivers it in spades.

Take it from me: an R3000 Indigo with a full 96MB of RAM, a complete suite of compilers and freeware, and the Starter Video option is one of the most entertaining computers you can find.

It's even common knowledge that the R3000 Indigo is more reliable than its R4k counterpart, in the realms of both hardware and software. In the past, when planning out my Home Network(TM), I opted for the pragmatic economy of R3000 Indigos over anything else. For over a year, an R3000 Indigo served this web site and many others to the entire world, and another one offered services like DNS, mail, bzflag, and more.

(Yes, those R3000 Indigos were phased out and replaced with an R5000 Indy -- which was since phased out and replaced with a rackmount 300MHz Celeron machine running OpenBSD 3.3, which was since phased out in favor of a remote hosting service -- but only because I wanted to scale back my electricity usage. Those machines were rock-fucking-solid, with years-long uptimes that were only interrupted by power outages, and to this day I still think R3000 Indigos are quite keen.)

So don't get the idea that R3000 Indigos suck. They're just older than their R4k successors, and with this fact comes a few caveats.

It's a bit like watching the country of Zimbabwe. For over a decade, Silicon Graphics was a cool, inventive company that made groundbreaking computers. Since about 1997, however, they've been on the slide.

The first sign of the apocalypse was when Silicon Graphics started producing -- ptui! -- Windows NT workstations. Then, in a grim-yet-wacky attempt to improve their public image, Silicon Graphics officially renamed the company to "SGI" ("Servers, Graphic Workstations, and Innovation!"), destroying a prominent brand that had existed for well over a decade. Even their funky "cube" logo was put to bed.

With the advent of cheap supercomputing clusters and killer consumer-level 3D graphics, SGI's hold on the industry has almost hit bottom. One day, I believe, SGI will bite it (i.e., get bought out), and their computers will disappear, with the possible exception of the super-high-end models. I've never been good at predicting the timing of these things, but even if it happens next week, the hobbyists can still survive like roaches.

Still, I don't wish SGI any ill will. They can still make cool computers -- the Octane2 is a testimony to this -- so maybe they have a few more rabbits they can pull out of their hat.

Good for you! To wit:

Here's where my opinions currently stand:

CPU: Get an R4k Indigo. Yes, we're only a few paragraphs away from my devoted love song to the R3000 Indigo, but I still recommend you to get one of its R4k successors. This is because of improved software availability and processor speed. If you enjoy that old-school retrocomputing thing, then by all means get yourself an R3000 Indigo; these computers are super-cool and you'll have a grand old time. But for everyone else, the benefits that come with the R4000 (or better yet, the R4400) are well worth it.

If you have an R4000 Indigo, I recommend tracking down an R4400 upgrade. They're only $15 or so on eBay and the performance boost is worth every penny.

OS: This is a little more opaque.

If you have an R3000 Indigo, IRIX 5.3 is the end of the road; it works quite well and it's super-stable, especially if you get the final patchset, so this is an easy recommendation. But I have to admit: IRIX 4.0.5 is pretty darn cool! I've had a great time fooling around with it.

If you have an R4k Indigo, go with IRIX 6.5. IRIX 6.2 isn't bad, all things considered, but ponder the following caveats:

Comparing IRIX 6.5 to 6.2: the response of the windowing system is slower in IRIX 6.5, although the base system is faster. This gives the user an immediate perception that the Indigo is underpowered for IRIX 6.5, although that perception is cosmetic alone. For everything but the UI, IRIX 6.5 is measurably faster than 6.2.

Here's a quick checklist of the vitals; more links are listed below:

Contact an SGI sales rep and order a copy. It's easy!

Well, alright ... I'm afraid you're stuck to scouring the second-hand market. A particularly good place for this is eBay. Keep in mind that buying IRIX installation media from agencies other than SGI is a violation of the licensing agreement, so it's technically illegal. Blah blah blah.

Besides, SGI won't even sell you a copy of IRIX that predates version 6.5. So if you have an R3000 Indigo, you have no choice but to live outside the law. Solidarity, comrade!

Easy: the Indigo is only capable of booting from select CD-ROM drives. So if you are buying a CD-ROM drive for an Indigo, take care about which drive you purchase, depending on your needs.

(Essentially, for a drive to be bootable, it needs to be able to use a 512-byte block size. This usually isn't advertised as a feature, so you're better off going by brand and model.)

Keeping a comprehensive list of SGI-bootable CD-ROM drives would be sisyphean; generally speaking, people say that you'll have best luck with drives from Toshiba, Sony and Plextor, with Teac, NEC, and Yamaha being reasonable alternatives. Avoid CD-R or CD-RW drives, unless you specifically need those features. (From what I've read, it's probably best avoiding CD-RW drives altogether.)

The most-reliable CD-ROM drives you can find are the ones originally sold by SGI that were coeval with the Indigo, namely:

• Toshiba XM3301B (1x, caddy)
• Toshiba XM3401B (2x, caddy)
• Toshiba XM3501B (4x, platter)

Unfortunately, good luck finding someone who thinks that a 4x CD-ROM drive is compatible with a twenty-first century computing environment.

There are three general functions to be had from CD-ROM drives, when used with an older SGI, and depending on which drive model you choose, your performance with any of these three will vary:

1. Reading data: Accessing data from a CD-ROM, once the computer is up and running from a working installation of IRIX.
2. Booting and installing: Booting from an IRIX installation CD and installing a new system to the computer's hard disk.
3. Playing audio CDs: Duh. This can be accomplished either by having "audio over SCSI", where the audio data is sent over the SCSI bus, or the old-fashioned way, by having the audio played over the CD-ROM drive's audio-out ports.

While the Indigo is picky about which CD-ROM drives it can use for reading data, when it comes to booting and installing system software from a CD-ROM, it can be described as downright fickle. This is because when a fully-booted Indigo uses a CD-ROM drive, it's using device drivers that are as recent as its version of the operating system. Conversely, when the Indigo boots and installs from a CD-ROM, it's running from the PROM and using firmware-based device drivers, which haven't been updated since the computer was born in the early '90s.

If that's not bad enough, playing audio CDs on an Indigo is generally a lot more of a hassle than it should be. Most of the software CD players built into IRIX have a low level of compatibility (i.e., Toshibas and Sony units only), so don't expect a lot if you're using a different brand of CD-ROM drive. You might be able to get it to play out of the headphone or audio-out ports, but only if you're lucky.

The important morals for you to take home:

• If a CD-ROM drive works on a computer that's already up and running, it won't necessarily work as a boot device, or as an audio CD player;
• Of the recommended brands mentioned above, you'll have better luck with older/slower drives than newer/faster drives;
• Because age is the demon, R3000 Indigos have a smaller selection of bootable CD-ROM drives available than do R4k Indigos, and even older R4k Indigos have a smaller selection than do newer R4k Indigos;
• If someone is selling a CD-ROM drive and advertises it as "SGI bootable", it may indeed boot for some of the recent SGI models, but not the Indigos.

It is common for hobbyists to keep around one of the primordial SGI-issued (1x-4x) Toshiba CD-ROM drives for the sake of that initial IRIX installation, but switch to one of the newer (24x and above) models once the system is up and running. Myself, I use a 12x Toshiba XM5701B, which plays audio CDs and reads data CDs on my R4k Indigo, and I keep a Toshiba XM3401B in the closet for installations.

I actually get this question a lot, from people who acquire Indigos secondhand. If you don't know much about the Indigo, it's understandable that you might not know the dichotomy exists. Fortunately it's easy to differentiate them.

If your computer is running: type hinv at the command line. The output will have the answer: if there's a line that says something like, "CPU: MIPS R3000A Processor Chip", then you have an R3000 Indigo. But if there's a line that resembles, "CPU: MIPS R4x00 Processor Chip", then intuitively enough, you have an R4k Indigo, with the described CPU.

If your computer isn't running: inspect the motherboard. The R4k Indigo has the processor mounted on a daughtercard near the front of the motherboard. (It's very easy to spot. Just look for the ugly-mutha heat sink.) The motherboard for the R3000 Indigo is very simplistic: it has no daughtercards at all, and no heat sinks. The only things you can attach to it are the RAM sticks.

Like the above, the best way to make sure is with the command hinv. The output will contain a line that resembles one the following examples:

Graphics board: GR2-Elan
Graphics board: LG1

"LG1" translates to "Entry Graphics". "GR2" translates to "Express Graphics", and the successive qualifier tells you what specific level of Express Graphics you have. (E.g., "ELAN", "XZ", "XS-24", etc.)

Many other upgrade options are recognized and displayed here as well, provided you have the proper driver software installed. E.g., if you have the Starter Video ("Indigo Video") board, you'll also see a line that says:

IndigoVideo board: unit 0, revision 2

If your computer isn't turned on: take a look at the ports on its hindquarters. "Entry Graphics" has two monitor ports -- one for 13W3 "workstation" monitors, and another for standard VGA monitors (DB15). Express Graphics has only one monitor port (13W3), but it has a "3-D" port (for 3-D stereo glasses) and a BNC "Genlock" port. (To be pedantic, some variants of Express Graphics have two BNC Genlock ports, labeled "Genlock in" and "Genlock out". They're not common, however.)

Sometimes in eBay auctions, the seller will post a photo of the Indigo's backside. By counting the ports on the GPU, you can determine which graphics family it belongs to. Entry Graphics cards have two ports; Express Graphics cards have three (and on occasion, four).

(Additionally, the Starter Video board will have a bevy of RCA and s-video jacks and a DB15 RGB port. The Galileo Video board has two crazy-looking high-density ports.)

For more detailed information about your computer's graphics, use the command /usr/gfx/gfxinfo. It will actually give you a specific component-by-component report on your computer's graphics subsystem. It will even make an educated guess as to what kind of monitor it's hooked up to.

If the computer is running, use the command uname -R. This will give you the full version number. You can also determine the IRIX version when you turn on the computer: look sharp, and you should see the version number appear as part of the scrolling boot messages.

If you have an Indigo that is having problems, there are two initial things to try. (Make sure your computer is powered down when attempting these.)

First, blow out all the dust. The Indigo is like a vaccum cleaner, and if you leave it too close to the floor, it'll clean your carpet really well. Actually, it's better than a vaccum cleaner; it's more like a HEPA-filter. Even if your Indigo is nowhere near the floor, it'll suck so much dust out of the air, you'll start to get paranoid about all the crap you're inhaling.

All this dust gets inside the computer, and it can cause some pretty wacky problems, from slightly erratic behavior to apparent death. But if you have a strong pair of lungs (or a nearby leaf-blower), you should be able to clean it out pretty well. Don't forget to blow out the power supply (from the back, through the fan). When any of my Indigos ever gets twitchy, this usually does the trick.

Next, re-seat all the boards, drives, and RAM modules. That is, pull them out and stick them back again, securely. (Make sure you're grounded, obviously.) The Indigo's ease-of-disassembly does have its drawbacks, and sometimes these components can come loose, especially after shipment.

And if none of these strategies work, and you don't have any definitive clues (e.g., error messages) then I'm afraid you're on your own. At that point it's anyone's guess.

This happens frequently to Indigos that are stored for long periods of time, and because of the advancing age of these computers, it's happening more and more frequently. Thankfully it doesn't mean that your Indigo is "completely dead". This problem happens all the time and it's only fatal for the computer if you let it be.

Are you sure everything's seated properly? Or maybe you killed something because you weren't properly grounded? Or maybe there's a dust problem; be sure to blow everything out thoroughly, including the power supply. Or ...

• If you are encountering this problem after upgrading the GPU from Entry Graphics to Express (i.e., XS-8 through Elan) Graphics, then you might have one of the weird Indigos with a boot EPROM that is only compatible with Entry Graphics. Bummer, dude. This happened to me, back when Indigos cost real money, so I feel for ya. You can get around this by either (a) finding an Indigo nut with a ROM-burner, or (b) buying a new Indigo.
• If you upgraded the GPU from Entry Graphics to Express Graphics, like the scenario above, and the computer boots but gives you serious problems with the graphics output, then you probably didn't reinstall the operating system. Many of the OpenGL libraries are specific to GPU families.
• If you are upgrading the CPU board from R3000 to R4k, you also need to upgrade the power supply as well. (By part number: The R3000 PS (210W) is 9430810; the R4k PS (250W) is 9430812.) If you upgraded your power supply and are still experiencing problems, then you may be confirming the rumor that there are Indigo variants with CPU-specific NVRAMs in the backplane. The only way around this is to purchase a new Indigo, at least that I know of.

In any case, try going back to your original configuration; if the computer still works, then I'd put money on one of the above bad-luck scenarios. If the computer still doesn't work, then I think yer hosed.

Sorry, bub, it sounds like your Indigo's power supply is giving up the ghost. As soon as you can, get a new PS -- or if you can afford it, get your troublesome PS repaired, preferably by someone who knows what they're doing. Having the computer spontaneously shut down isn't good for the filesystem (or the hardware), so leave the computer turned off until you can get the power supply fixed or replaced.

I know, once you get used to (or come to rely upon) 100Mbit or gigabit networking, 10baseT is a bitch. Unfortunately there are only two workarounds that I know of.

1. The practical solution: locating either a Phobos G130 10/100baseT ethernet card or a Set Engineering 10/100baseT ethernet card (designed for the Indy and Challenge S, but it reportedly works fine in the Indigo).
2. The spiffy solution: resort to an alternate means of high-speed networking (e.g., FDDI or ATM).

The Phobos/Set 10/100baseT cards aren't terribly difficult to find, especially if you're not too stingy; the ATM/FDDI cards can be described as rare, perhaps even very rare.

Yes, of sorts. If 4Dwm (the default IRIX X-Windows manager) freezes up, press the following four keys simultaneously:

• LeftShift
• LeftCtrl
• NumericKeypad /
• F12

This will take you back to the login screen, if all goes well.

No. If only life were so simple. The vast majority of IRIX software is licensed and/or nodelocked, which means it won't work unless (1) you spend some money, or (2) you can find a work-around.

Some might say that spending money is easier than finding a work-around, but that's only true if you have more money than time. Of course, we're entering the realm of software piracy, so I can't endorse any of this, but at the same time this isn't exactly uncommon knowledge.

The HotMix CDs are collections of software demos that were handed out by SGI as promotional items. There were twenty or so editions, and some people have been very keen on collecting them (see what happens when you put volume numbers on things?), but I must say their allure has escaped me.

The IndiZone CDs are collections of games and utilities, the winners and honorable mentions of SGI's game-programming contests back in the mid-90s. There are three volumes of IndiZone CDs, of which volume one is the least common. Personally, I think they're nifty and worth tracking down. Some of the games are a serious kick and they seem to work with most everything that runs IRIX 5.3 and above.

No. I offloaded my entire Indigo kit, plus another 1,600 pounds of techno-effluvia, so my personal stores are low. But if you ask nicely, I might be able to refer you to someone.

Okay, this isn't really a frequently asked question, but I allow myself some evangelism from time to time.

This hack rocks the house. I've had my R4400 Indigo hacked thusly since January 2003, and it ran happily with no problems up to the day I sold it (in September 2005). I cannot recommend this hack any more highly. (Granted, I kept around a spare R4400 processor with the original heat sink, just in case, but I never needed it.)

Many reasons. Like everyone else, I'm busy and I'd rather spend my time doing new and exciting things. Plus there's not a whole lot going on in Indigo-land, as of late. Even if the Indigo scene was hopping, I'm out of the game myself, and updates are now few and far between. Sorry about the inconvenience.