Does the Mac Developer Program have old versions of Mac OS X?
I'm developing something for Mac OS X. It's a port of a Windows product.
One of my boss' concerns is how it will run on older versions of Mac OS X. I know Xcode has facilities for compiling for old versions of Mac OS X, but QA would prefer to actually run the older versions of Mac OS X on a Macintosh.
Since we got into Macintosh development after Snow Leopard was released, all of our machines come with Snow Leopard (10.6). As far as I know, you can't really walk into a store to buy Leopard (10.5) and anything prior to that is basically extinct.
In a question on virtualization someone said that they've done multi-boot or multiple hard drives for other versions of Mac OS X, but I'm not sure how one would obtain the install media or the license for an old version.
I see Apple has their Mac Developer Program which touts as one of its features as "access pre-release versions of the latest software" which is cool, but I don't see it anywhere on there that old versions of Mac OS X are available. Does Apple have an MSDN-equivalent where old versions of the software are available for download?
Also, is there a reliable breakdown somewhere of the rate of upgrades/updates to Mac OS X? (i.e., what % of users still run Mac OS X 10.5, 10.4, PPC-based machines, etc.)
Answer
In case you buy an old OS X from Amazon or other retailers, note that you can not install an OS which was released before the hardware was announced. Older OSes just don't have the required driver to be able to run on a newer machine, and Apple doesn't back-port drivers for older OSes. In other words, if you buy the latest new Mac from Apple, you can't install 10.5 or 10.4 or whatever. So, you need to buy an old Mac too, not just an old OS.
The breakdown of the OS ratio really depends on the software. For example, the veritable Omnigroup publishes this version breakdown of the hits of their software update server. There are many websites which tell you the version break down, see e.g. this site.
Judging from it, I would say Snow Leopard covers half of the Macs in the world. Supporting Leopard might be worth while if you have extra resources. But I would guess people who didn't buy Snow Leopard won't typically buy a new 3rd party app, so supporting Leopard won't give you 50% increase in the number of potential buyers. (I admit this last sentence is completely subjective, though.)