OS X Yosemite runs on same Macs as Mavericks, but iOS 8 drops support for iPhone 4
Any Mac currently running Mavericks will be able to install OS X Yosemite, hardware requirements released by Apple show. But the launch of iOS 8 this fall will mean the end of support for the iPhone 4, first released in 2010.

The system requirements for Yosemite listed by Apple are identical to those for Mavericks, which means that the following systems will be able to run OS X 10.10:
But this fall's debut of iOS 8 will leave the iPhone 4 in the dust, finally retiring support for Apple's A4 chip. The oldest phone that will be supported by iOS 8 is the iPhone 4S, which is powered by Apple's A5 CPU.

That same A5 chip is also found in the iPad 2 and first-generation iPad mini, both of which are also capable of running iOS 8. That means that all iPads that were capable of running iOS 6 and iOS 7 7 will be able to install the iOS 8 upgrade. Apple retired support for the first-generation iPad and its A4 chip with the launch of iOS 6 in 2012.
Both iOS 8 and OS X Yosemite will be free upgrades for Apple device users coming this fall. Continuity between the two platforms has been a key focus for Apple in their development.

The system requirements for Yosemite listed by Apple are identical to those for Mavericks, which means that the following systems will be able to run OS X 10.10:
- MacBook Pro: mid-2007 or newer
- MacBook Air: late 2008 or newer
- iMac: mid-2007 or newer
- Mac mini: early 2009 or newer
- Mac Pro: early 2008 or newer
- MacBook: late 2008 aluminum, early 2009 or newer
- Xserve: early 2009
But this fall's debut of iOS 8 will leave the iPhone 4 in the dust, finally retiring support for Apple's A4 chip. The oldest phone that will be supported by iOS 8 is the iPhone 4S, which is powered by Apple's A5 CPU.

That same A5 chip is also found in the iPad 2 and first-generation iPad mini, both of which are also capable of running iOS 8. That means that all iPads that were capable of running iOS 6 and iOS 7 7 will be able to install the iOS 8 upgrade. Apple retired support for the first-generation iPad and its A4 chip with the launch of iOS 6 in 2012.
Both iOS 8 and OS X Yosemite will be free upgrades for Apple device users coming this fall. Continuity between the two platforms has been a key focus for Apple in their development.
Comments
I hope the features between iOS 8 and 10.10 will be available on all handsets, tempted to keep my iPhone 4s another year but really want to use my Mac to answer my phone whilst it's on charge etc.
Thanks to Apple who still willing to support over 3 generations old iphone, ipads, Macs, etc. AND
Big NO thanks to Google android and those selling android phones who hardly care to support last year's models with year old kitkat android 4.4 version. I am waiting for my LG Optimus e970 for kitkat update. Samsung dropped galaxy s3 from kitkat update and the list go on and on and on. I am sorry, it is big list to list here but you know what I am saying if you are android smartphone user.
I doubt features would be limited for the 4S since the 4S ran iOS 7 fine. I would assume most of iOS 8's improvements aren't processor intensive.
Any evidence of that? Remember iOS 7 only gave panorama shots to the newest iPhones. I see that iOS 8 is bringing panoramas to the iPad, but you can bet the iPad 2 and 3 won’t get that.
I am still using a Late 2008 MB at work. I replaced the HD with an SSD and I have no speed issues at all. Looks like I'll be keeping it for a while longer. Color me impressed. A 6 year old lap top running the latest OS without a problem. Runs all the apps fine inc PS6 (not for heavy lifting).
We still have a Mid 2007 iMac at home used mainly by my wife. I'm (pleasantly) surprised that it made the cut for Yosemite.
The question is will I be tempted to change my iPhone 4S when the new phone(s) is(are) released?
Amazing.
The question is will I be tempted to change my iPhone 4S when the new phone(s) is(are) released?
I am always tempted
In the end I usually end up changing when the device I am using becomes unbearable. Its not that I resist the temptation. I'm just lazy. The 4s is still a pretty capable phone and if its in good condition its amazing how much you can get for it.
It is always sad when old devices are no longer supported but for developers there is a silver lining: The iPhone 4 will always run iOS 7 for backwards compatibility testing. Apple has very few ways for developers to test their apps on older versions of iOS on physical devices. Good luck trying to buy an old device on eBay that runs a particular version of iOS you want to test. If we don't have a particular device/iOS version combo, we just hope for the best so it is great that at least one device will always run iOS 7 for testing.
The best news is that iOS 8 won't be hobbled on any of Apple's older iPhones in the way that iOS 7 was limited on the iPhone 4. Every iPhone will get the full iOS 8 experience.
source?
Guys I am now thinking what about iOS 9. What devices do you think iOS 9 will support?
If we are following the logic that a device can now support 4 years worth of OS, the iPhone 4S and iPad 2 IMO will not support iOS 9.
If we are following the logic that a device supports a OS based on the SoC, iPhone 4S, iPad 2, iPod touch 5th generation, iPad mini 1st generation and iPad 3rd generation will not support iOS 9. (iDevices running on A5 chip, including the odd out A5X)
I think Apple will do something weird next year, having iPad mini 1st generation and iPad 3rd generation running iOS 9, but not on iPhone 4S and iPad 2.
My prediction on iOS 9 compatible devices:
iPhone 5, 5c, 5s, 2014, 2015
iPad 4, Air, Air 2, Air 3, mini 2, mini 3, mini 4
iPod touch 6
I think iPad mini 1, iPad 3 should not make it into the list. This will make the lineup consists of A6, A7, A8 & A9 chip only. I think this will make the engineering smoother in general for the entire lineup.
Then in iOS X, maintain the same lineup i.e. iPhone 5 and 5c can still run iOS X.
I am still using a Late 2008 MB at work. I replaced the HD with an SSD and I have no speed issues at all. Looks like I'll be keeping it for a while longer. Color me impressed. A 6 year old lap top running the latest OS without a problem. Runs all the apps fine inc PS6 (not for heavy lifting).
I have a mid year 2009 Macbook Pro at home. Same thing. I replaced the hard drive with a SSD. It is quite fast. I would, however, enjoy some of the newer capabilities in terms of things like being able to stream from a Mac to an Apple TV. IN some ways I prefer the older Mac because of things like the built-in DVD burner, which I still use.
In case anyone was wondering, I was able to upgrade from 10.7.5 to 10.10 (DP) without any issues at all. I had a test Mac that only had 10.7.5 installed so I ran the upgrade and it worked fine. I can test from 10.6.8 if anyone is interested?
And my Early 2008 MacBook Pro is smiling from USB port to USB port.
Ran every Mac OS beautifully, from what it came with right up to Mavericks. Stuck more RAM in it in 2009 to bring it up to 6GB. Still chugging along nicely.
Its not just a problem of processor but also RAM. The iPad 1 had the same processor as the iPhone 4 but could not run iOS 7. We will just have to wait and see.
All devices running on iOS 7 has at least 512MB RAM, so you are right. Getting rid of all A5 equipped devices seems to be the reasonable choice, and iPad 1 ran on iOS 3 4 5, so assuming the same logic, iPad mini 1st generation run on iOS 6 7 8 and then discontinued. That's just my opinion
I have a mid year 2009 Macbook Pro at home. Same thing. I replaced the hard drive with a SSD. It is quite fast. I would, however, enjoy some of the newer capabilities in terms of things like being able to stream from a Mac to an Apple TV. IN some ways I prefer the older Mac because of things like the built-in DVD burner, which I still use.
You should be able to stream from iTunes to your Apple TV - I can and do that occasionally, although at home I have other more capable devices. As far as burning DVD's I haven touched a DVD in years. In fact, on my old MB I removed it an put in another SSD. I was given a DVD set of a television series for my birthday and couldn't watch it. No DVD or CD players in our house. I felt justified in bittorrenting the series.