If you're like many geeks my age, your first real exposure to Silicon Graphics, Inc., and all their neat hardware was either when Nintendo Power did their feature article on the making of Donkey Kong Country. Or maybe it came while watching Jurassic Park, when the teen genius Lex proclaimed "This is a Unix system, I know this!" - or when her brother said more or less the same thing in the novel. Or maybe you once saw one of their famous demonstrations at a convention. Or perhaps you had a few in the computer lab at your university. However you were first introduced, you now want one of these keen machines for your own.

Well, as an avid collector, I can understand why! They're made well, they were some of the most capable machines of their time, and a lot of them are still surprisingly capable even now, as much as thirteen years after they were first made. By way of comparison, a PC of that age is just about useless, and even a Sun is getting rather long in the tooth.

Also, like Macs, SGI systems are well integrated and provide a good, cohesive experience. They also include the cool IRIX Interactive Desktop, which was once called Indigo Magic Desktop, a desktop environment for X that cleaner and more functional than any other Unix desktop of its time. It's still better in some ways than KDE or GNOME. When it was introduced it was every bit as slick as the Windows, OS/2, RISC OS and Macintosh desktops of its time.

So, which SGI should I get?

SGI was the first real graphics workstation company, with their history going all the way back to 1981. They're as old as Sun, and their product lineup has every bit as much history in it. Like Sun, though, they are most famous for their more recent machines. Just as Sun became most known for systems based on their own SPARC processor, so did SGI become famous for their systems based on the MIPS processor series.

The first Silicon Graphics systems were Motorola 68000-based systems, like so many other workstations of the early 1980s. These were largely boring beige boxes with graphics capabilities that were, for the time, downright impressive. However, SGI, like most other computer makers of the time, saw the limitations of the chips they were using, and the possibilities presented by the new RISC architectures. So, while HP jumped ship for PA-RISC, and Sun for SPARC, and DEC held onto VAX for dear life while Alpha was developed, SGI latched onto MIPS. Their first MIPS machines, called IRIS 4D, ushered in the age of Silicon Graphics as we know them today. However, it's fair to say that the machines of the early IRIS 4D era are far too slow to be of much use today.

It was the next array of machines in SGI's lineup that would capture the industry's attention. First up was a large deskside machine called the IRIS Crimson, made famous by its appearance in Jurassic Park. The next was the IRIS Indigo, a small, innovative desktop workstation.

Recent SGI machines

Recent SGI machines can be broken into three overall generations, though it's really a bit more complicated than that. As each generation went on, new variants were introduced that formed a sort of bridge to the next generation. It is simpler, however, for the purposes of a basic buying guide, to treat them as three separate generations.

This writeup largely ignores the Origin and PowerSeries server/supercomputer-class systems, and completely disregards the x86-based Visual Workstation series. Note that the Fuel and Tezro did technically bear the moniker "Visual Workstation", but as they were MIPS-based systems, they are covered here.

First-generation modern SGIs

All first-generation machines save the Onyx employed some variant of the GIO bus, though even for nominally-compatible versions of GIO, like on the Indigo and Indy, there was never a common form factor. Most of them use the Newport (2D) and Express (3D) graphics options, though the late-model Indigo2 systems use the higher-end IMPACT graphics system, also used in the second-generation Octane.

IRIS Indigo
Officially the last of the IRIS series of machines, but the IRIS Indigo was quite a bit different from the previous IRIS 4D series. It comes in a cute little blue mini-tower case which is widely regarded as one of SGI's best case designs ever. Drives slot in on the right, graphics cards and other GIO32 expansion cards on the left. Two versions were made, one with MIPS R3000 processors at 33 and 50MHz, the other with MIPS R4000 processors at up to 150MHz. This machine is limited to a maximum of IRIX 6.2, IRIX 6.5 will not run.
Overall Rating: The IRIS Indigo is just new enough to be interesting for a beginning collector, but the fact that it won't run IRIX 6.5 is problematic. They also use proprietary and hard to find keyboards and mice, unlike the PS/2 and USB used by later machines. Just avoid.
Indy
Jokingly referred to as an "Indigo, without the go", the Indy is a small, entry-level workstation. Its offset pizza box chassis is distinctive, one of the best-known SGI machines. Although often thought of as a neutered Indigo, it's actually a fairly capable little machine. It's available with XZ graphics, a smaller version of the medium-high option on the Indigo, which makes it a useful 3D machine, too. Several processor options are available; the R5000s are far and away the best.
Overall Rating:A great starter machine, with tons of integrated features. IRIX 6.5.19 is the latest it'll run, and it doesn't have nearly the 3D grunt of an Indigo2, but it's a fantastic machine to get started with.
Indigo2
The Indigo2 officially replaced the IRIS Indigo as SGI's flagship desktop workstation. It featured the new, improved R4400 and R4600 processors and the new GIO64 expansion bus, supporting improved versions of the Express graphics system from the Indigo and Indy. Indigo2 also included EISA expansion slots in an attempt to be more industry-standard. All this came packaged in a large, heavy, exceptionally durable slab case with teal plastic skins. Though regarded as boring by some, I consider the Indigo2's case to be a classic example of excellent design and engineering.
Overall Rating: Pretty solid, but not worth much more than a tricked-out Indigo. The updated Indigo2 variants that appear later are much more useful. However, a 200MHz R4400 Indigo2 with Extreme graphics still makes a usable desktop system.
POWER Indigo2
A newcomer to SGI machines might be forgiven for thinking that this is a variant of the Indigo2 based on IBM's POWER series of RISC processors. It's not. Instead, it's an updated Indigo2 based on the MIPS R8000 processor, one of the few RISC CPUs to appear as a chipset, and not a single chip. In large part because of this, the R8000 only ever ran at 75 and 95MHz. The POWER Indigo2 only shipped with the 75MHz version. Surprisingly, even at that speed, the R8000 ran circles around the R4400 for floating-point math, although the R4400 was a stronger performer at integer math. Most of these came with the darker teal skins of the Challenge M, but some had the teal skins of the standard Indigo2, while a very few had the purple skins of the Indigo2 IMPACT.
Overall Rating: Nice machines, but hard to find and finicky. Also, most cannot take IMPACT graphics cards, while Extreme boardsets are hard to find.
Indigo2 IMPACT
Roughly contemporary with the POWER Indigo2, this is an R4400 Indigo2 modified to accept the newer, more capable IMPACT-series graphics cards. These were a major step up, with even the entry-level card, Solid IMPACT, providing over twice the performance of the previous high-end option, Extreme. The new High IMPACT and Maximum IMPACT cards also had hardware texture support, a first in desktop graphics systems at the time. A very few of these, possibly prototypes, used a card called Killer IMPACT, which was essentially a half-speed Solid IMPACT. These machines have purple skins.
Overall Rating: A powerful and useful machine, and often quite cheap. Especially with the 200 or 250MHz R4400, it can be almost as fast as the later Indigo2 R10000. The biggest limitation is the 384MB RAM ceiling.
Indigo2 R10000
The successor to the Indigo2 IMPACT, these featured MIPS R10000 processors, which combined the high integer performance of the R4000-series with the high floating point performance of the R8000, plus high clock speed, and, like the R8000, true 64-bit computing. They made the POWER Indigo2 obsolete and irrelevant less than two years after its introduction. All R10000 Indigo2 systems supported IMPACT graphics and had purple skins. A few were sold with Express graphics instead, but could be upgraded.
Overall Rating: As the most powerful desktop machine from the first generation, but still little more expensive than an Indy or lower-end Indigo2, the Indigo2 R10000 is probably the best first-generation machine for the beginning collector.
Onyx
The Onyx is a huge, black, vaguely sinister-looking system, in either its rackmount or deskside configuration. Its whole purpose is to support the RealityEngine, RealityEngine2 and InfiniteReality graphics systems for high-end visualization and virtual reality. Deskside versions can support one system board and up to two graphics pipelines, while rackmount systems can have four of each. Each system board can have one, two or four R4400, R8000 or R10000 processors and up to 4GB of RAM. For its time, the Onyx was the last word in graphics performance. It's still downright impressive. Unfortunately, it's also a huge beast, and the rackmount version needs 3-phase power.
Overall Rating: Big, impressive, awesome, impractical. All of these words describe the Onyx. It's not a great machine for beginners - but if you can get one cheap, it's one hell of an interesting addition to a collection.

Second-generation modern SGIs

The second generation includes SGI's most famous workstations, the O2 and Octane. All of these systems use standard PS/2 keyboards and mice.

O2
The O2 is affectionately known to collectors as the "Blue Toaster", because, obviously enough, it's blue and looks like a toaster, if you use your imagination. It was the first SGI machine to include an internal CD-ROM drive standard; while the Indigo2 had it as an option, only the O2 always shipped with one. It uses the innovative CRM graphics system, which shares system RAM for both framebuffer and texture memory. While this is usually a performance killer, in this case it's useful because it allows the system to use images in main memory as textures. This also allows it to use live video as a texture, something few other machines, from SGI or otherwise, can match. CRM has hardware acceleration for some operations, but depends largely on the main CPU. Because of this, high-powered CPUs in an O2 are worth relatively more than in other workstations. The O2 was produced in 2 main variations, one with R5000 and RM7000 processors and two drive bays, the other with R10000 or R12000 processors and one disk bay.
Overall Rating: Small, convenient and reasonably fast, the O2 is a great choice for beginners. While it can do 3D capably, it is better as an audio/video machine than as a 3D graphics workstation. It may well be the best SGI for basic audio/video work.
O2+
The O2+ is practically identical to the O2, save that it sold only with the RM7000 and R12000 processor options.
Overall Rating: See O2.
Octane
The new flagship workstation, replacing the Indigo2 R10000. The early versions featured one or two R10000, and later R12000 processors and IMPACT graphics, and used a new I/O architecture called XIO, which made them faster in some cases than an equally-specced Indigo2. They also used faster disks than the Indigo2. The Octane dispensed with the industry-standard EISA, but in exchange allowed a cage to be installed that can take three PCI expansion cards. Most Octanes had teal skins. Some later-model ones used the blue skins of the Octane2, but without the 2 - these were basically just IMPACT-equipped Octane2s.
Overall Rating: Although the Octane is big and heavy, and occasionally expensive, it's a great machine for a beginner. Even a low-spec Octane is easy enough to upgrade, and the upper capability limit is very high.
Octane2
The Octane2 was in most respects equivalent to the Octane. The biggest changes were new revisions of the motherboard (which some Octanes also have), and of the XBOW XIO router chip. The Octane2 series supported the VPro graphics cards, and also the newer R14000 processor modules.
Overall Rating: A better machine than the Octane, but correspondingly more expensive. Actual blue-skinned Octane2s are actually rather expensive still, though generally under $1000 except for very high-end configurations. On the other hand, Octane machines upgraded with better CPUs and VPro graphics are much less expensive, and are equivalent to the Octane2 in all but name.
Onyx2
The Onyx2 is the designated successor to the Onyx, using the architecture of the Origin2000 server/supercomputer as a support system for the InfiniteReality, InfiniteReality2, InfiniteReality3 or RealityMonster graphics systems. Like its predecessor, it exists in deskside or rackmount configurations. It is equipped with up to four processors per system board, either MIPS R10000, R12000 or R14000. The deskside variant supports one system board, the rackmount up to eight. Like the Origin2000, it can take Octane XIO graphics cards, but there's no sane reason why anyone would do that.
Overall Rating: Just as big and impractical as the Onyx, but even more powerful. On the off chance you can find one cheaply, it would be a beast of a machine to have - but watch the power bill!

Third-generation modern SGIs

Fuel
The Fuel displaced the low-end Octane more so than it did the O2. It was in most respects a single-processor midrange workstation. Equipped with an R14000 or R16000 CPU, Ultra160 SCSI and VPro graphics (either V10 or V12), it was actually quite a powerful machine. Its lack of audio hardware is mildly annoying, but the easy-to-get M-Audio Revolution 7.1 or the somewhat less sexy Creative Labs Audigy2 ZS can remedy that problem.
Overall Rating: If you can find one inexpensively, the Fuel might be the perfect starter machine. It's fast, it uses standard USB keyboards and mice, and it doesn't require any weird 13W3 conversion or sync-on-green monitors, since its graphics output is DVI. They're not horrible in the price department either.
Tezro
The high-power cousin to the Fuel, the Tezro could have up to four MIPS R16000 processors and up to 32GB of RAM. Otherwise, it was very similar to the Fuel, albeit in a much less conventional enclosure. The Tezro's case was essentially a steel cube, surrounded by a four-lobed skin that vaguely gives the impression of a compressed Onyx2. It's a very powerful and capable machine, and still commands well over $1000.
Overall Rating: This is SGI's most capable desktop workstation, and in some ways is more capable than the deskside Onyx2, but it's still extremely expensive. This would make a decent beginner's machine, though, if not for the price.

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