The hobby of computer collecting is something that quite a few geeks tend to get into, whether accidentally or on purpose. For any type of computer out there, there's probably someone who collects them, whether it's ancient IBM mainframes and DEC minicomputers from the mid 1970s, early 1980s 8 bit home computers or late 1990s RISC workstations.
In addition to being an entertaining diversion, and truth be told, a bit of a money sink, it also gives the collector a ready-to-run heterogeneous network. This is perfect for learning the arcane incantations necessary to make various operating systems and types of hardware coexist and work together. Even in these days where all the world's an AMD64 running Windows and datacenters are rooms piled to the ceilings with Dells, quite a lot of places are still searching for a wizard who knows how to make their odd legacy hardware tick. And to boot, some collectible systems can be used for learning more modern software.
So, you've decided you want to start up a collection, eh? The first question is where to begin. There are really four major (and unofficial) categories: early home computers, personal computers, workstations or servers, and big iron. A quick overview of each is below.
In this context, the term home computer refers to the 8-bit and 16-bit machines common in the 1980s, sold for use in homes, and also to some of the late 1970s 8-bit kit computers, some of which were intended for office use. These machines are almost entirely obsolete nowadays, and have been for two decades or more. Most can be had for very little money, but are often in poor condition. Half the fun in collecting these is in the restoration. This sort of retrocomputing is as much about keeping a piece of history alive as it is about getting things that still do anything useful.
There are dozens, if not hundreds of different home computers. Some of the early ones offered only text mode, and often ran their applications on bare metal, without an OS, while later ones offered graphics and a proper OS. Most were single-tasking, but there were some exceptions. Some of the most popular are listed below:
A thin line separates these from their relatives on either end, the home computers and the workstations. In general, personal computers have a 16-bit or 32-bit processor, an operating system (often with multitasking), and some kind of decent graphics and usually, but not always, some kind of fixed storage. Most of these evolved from home computer roots, and became more powerful as time went on.
Some personal computers are useful for real work, while others are mostly curiosities, or useful for the occasional game or application that would otherwise rot in obscurity. Nevertheless, many attract loyal and dedicated followings - consider the number of people today still using an Amiga or a RISC PC!
Some examples of the type:
Workstations (and servers)
As originally conceived, workstations were microcomputers intended for real work, not the sort of experimenting that home computers were designed for. They were in general much more powerful, and accordingly much more expensive. Throughout the 1980s, 1990s and even early 2000s, workstations were the most power you could get at a single user's desk.
What, exactly, a computer had to have to count as a workstation varied greatly over the years. In 1980, the specification was for a 3M machine - that is, a machine with a processor running at one MIPS, one megaword of memory (4MB on a 32-bit machine) and one megapixel of screen real estate. By the late 1980s, the Acorn Archimedes A4000 was offering nearly that. By the early 2000s, the Macintosh and x86 PCs had mostly caught up to workstations on performance, and had operating systems that could compete with VMS and the various Unix dialects in use on workstations.
In the early days, most workstations either stood alone, or were connected to a minicomputer or mainframe for services beyond their own capabilities. By the 1990s, however, workstation-class hardware specialized for providing network services began to appear. These servers, as they were known, drove the minicomputer largely out of existence, and relegated the remaining big iron to specialist roles.
Some examples of the type:
Big iron is the category covering large, high-throughput machines. This can include older IBM, Bull or Honeywell mainframes, DEC minicomputers, Cray supercomputers or later machines that fall somewhere in between, like Sun's Enterprise 10000 or SGI's rackmount Onyx2. This is the stuff that every geek everywhere lusted after when it was new - but nobody could afford it then! Well, big iron only keeps its resale value slightly better than other computers, and now you could indeed have a Cray in your living room and an IBM System/390 serving your personal web page, all managed from your shiny deskside SGI IRIS Crimson Jurassic Classic!
Even though it's basically affordable now, with enough searching, big iron is still power-hungry, loud and huge. Because of this, it's a rare collector who has nothing but big iron in their collection, or who starts out with it.
Some examples of the type:
Any one of these is a valid place to start, but different people have different ideas about what's interesting.
eBay is probably the most frequently mentioned source for cast-off computer equipment, but it's far from the only one. Classified ads in the newspaper, and sites like craigslist are a good possibility, too. It's also worth keeping an eye on corporate and university surplus sales, yard sales and flea markets. Shows and swap meets are held in some areas, too - watch your local newspapers and search the internet. Finally, it's quite possible to obtain some perfectly working kit by dumpster diving.
Search quite a bit before you buy to get a good feel for what prices should be - you don't want to get ripped off, but you don't want to miss a deal either. Sometimes a low price means there's something wrong with the item, but especially if you have a large collection already, damaged goods can be alright. You may already have the parts or knowledge necessary to fix it. Remember that especially with obscure gear, a lot of people don't know much about it. The problem may be as simple as misconfigured software or a lost password. I once purchased a Sun Blade 2000 inexpensively simply because it came with no OS installed. With some types of gear, though, lack of software may be a showstopper.
Resources for collectors
The internet is a great resource for collectors. Some types of machines, especially Apple, Acorn and Silicon Graphics systems, have flourishing on-line communities of users, administrators and collectors. It's sometimes possible to dig up some very obscure information on line. There's also quite a lot of information to be found right here on E2!
Don't forget about resources you might find locally, too. Go to a few LUG meetings and ask around - maybe someone has an old Alpha they want to get rid of. Maybe one of them happens to also collect SGI machines. And don't forget, help can go both ways - maybe you have some stray RAM floating around that turns out to be just what someone else needs to revive their broken VAX. University CS departments are a good place to look, too, especially if you're a student, and occasionally even if you're not. Sometimes people will be glad to answer your questions, or at least point you at a good book or two. If you're a student, check around campus. A lot of universities used to have labs of Sun, SGI, Apple or IBM machines; some of them still do. There might be an old SGI Origin2000 in the basement that they might let you have a shell account on, if you ask nicely.
Sources: nekochan.net, sunshack.org, the Suns-at-home mailing list, lowendmac.com, wikipedia, E2 itself, personal experience.