Every community has it's own opinion on what constitutes "retro" - more than x generations ago, more than x years old etc.
Whilst it's very subjective, and the subject of much debate, will there (and should there be) any restrictions on the cut-off for "retro" here? Or is it enough that the mention of a subject should get at least some of us misty-eyed? :)
When starting out, I would like to keep this definition as open as possible so we don't start off by flogging unsuspecting users with some pedantic definition of retro… at least until we see an actual encroachment of those "we didn't really intend this" problems in actual practice.
I like the general concept of Retrocomputing according to Wikipedia. Because of their ubiquity, I would suggest sticking to their example as much as practical. They don't put a specific timeline on the age of the equipment, but their descripton is somewhat suggestive of computer systems that are no longer widely in practical use, but are preserved mostly in the hobby and preservationist arena for their historical and sentimental value.
Retrocomputing is the use of older computer hardware and software in modern times.
Following that premise, I would consider a retro-system as anything that a reasonable person would not consider contemporary to what is modernly available.
…not considered contemporary to what is modernly available.
Contemporary does not mean "went out of fashion yesterday." I know that leaves things a bit fuzzy, but it's a start — bring us your Magnavox Odyssey and Commodore Pet questions; the original Xbox and Dell Optiplex aren't quite there, yet.
I wouldn't try and draw a hard line that says {x} years or older is okay, but the year after that is not. Such judgements are largely dependent on the type of equipment and how it is currently deployed (or rather, not). But I don't expect this to become the Super-User alternative to support deprecated hardware simply because an iPhone 5 is considered sort of old hat while Windows XP passed the sunset of support. That is not the purpose of this site.
I'll stop there. I don't expect to resolve this on day one (or in hour one, actually), but it's a scope that I would let develop organically and refine as actual problems start to occur regularly in actual practice.
Enjoy.
The definition of retro is:
imitative of a style, fashion, or design from the recent past.
Thus this site should be about computers and related products around 15 plus years old. These products should not be that common in our current era, like the IPhone 6. Products old from like the 1960's should be well suited to this site.
I think that we need to reach a verdict on each topic separately, because some things are obviously in scope, and other things are obviously not. Age has something to do with it, but retro computing is not only about age. Because new products are coming out even in recent years that are compatible with the popular platforms from the past.
Windows 7, off topic, even though it's end-of-life
RC2014, on topic, even though it's still selling
iPad, off topic, even though the early models are not for sale any more
AY-3-8912, on topic, even though it's not really computing
We are here because we are interested in something surrounding the old computers. That's probably connected to nostalgia, or expertise, or profession, or whatever. So we should canonise what we consider "on topic". Let's not keep revisiting whether we want to start accepting Java 8 questions next year or whenever. That's not a topic we're interested in.
In the interest of a broad audience, I would consider everything retro that hasn't been sold for some time, let's say ten years.
I pulled this number out of my head, but I believe that it's enough to keep out questions asking merely about used hardware while keeping some more recent but still retro devices on topic.
In addition to some of the other definitions mentioned, I would also suggest that obsolete architectures can be considered retro after less (not zero) time has passed since production ended. For example, the PowerPC Macintosh era ended in 2006 with later Mac computers being built on an x86 platform. So, I would allow a question about a 2005 Power Mac while probably disallowing a question on a 2005-era Dell PC running Windows XP, because the XP PC is built on substantially the same architecture as modern PC's. The XP PC is old, but not really retro because it doesn't look substantially different underneath.
Some obsolete architectures that would then be obviously on-topic would include:
A claim of "Well, your Irix box was manufactured in 2006!" would be literally true, but would not be sufficient reason to close because the Irix architecture has firmly passed in the retro universe.
I would generally apply this rule only to PC's and not video game consoles, as consoles are often their own unique architecture. For example, the fact that the Nintendo Switch is not just a souped-up 3DS, but its own architecture, doesn't mean that the 3DS automatically becomes retro.
Based on that discussion, I’d say that the manner of current usage is more important than duration of time since stopping production, ceasing sales, etc.
Windows XP is an everyday operating system yet ⇒ not retro.
The fact alone that millions installations exist doesn’t matter much. But XP is used in a daily fashion by businesses and individuals who are, say, unwilling to upgrade their software (although most certainly have such options). They installed it in early 2000s, and used it since (perhaps occasionally remaking the installation due to hardware and software failures), and nothing is about retro here.
In contrast, production of parallel SCSI devices continued into 2005, but the technology may be considered retro.
Surely the bus has a noticeable current use (at least, to access legacy devices lacking modern serial interfaces), but no computer engineer in a sane mind will nowadays deploy a parallel SCSI system for serious production.
On the other hand, some important notes should be recorded.
Firstly, if a specific model of computer or software is long obsolete or rare, it doesn’t automatically made any related stuff on-topic. Some its aspects may be long obsolete and thus on-topic, but other aspects may be identical to extant systems and hence off-topic.
Secondly, the definition of “retro” systems should be monotonous. Ī̲ mean, while Windows XP is deemed not retro, any successor thing (such as Windows Vista) may not qualify as retro.
I think a range of 15-20 years old is good-enough to mark something as a recent addition to the retro-tech classification.
Or to be pithy about it: "If it's old enough to vote, it's retro."
As an example, I recently found a box of old hardware in the garage, enough to build a functional PC out of, that dates from the early 2000s. It's all AGP and PCI slots with IDE drives, and I'm certain it uses some sort of 32-bit Athlon CPU. Is that retro? Maybe. It's certainly in the 15-20 year range and it is fairly different from the PCI Express and SATA used in my current Ryzen-based desktop machine. If you called that box of hardware retro, I wouldn't object. If you said "wait a couple more years", I'd probably shrug and say "okay".
