WHY IS SIRI LIMITED TO THE IPHONE 4S?
The cynical answer, of course, would be that Apple is withholding it from other iOS devices in order to spur additional upgrades to the iPhone 4S.
A non-cynical answer would be that Siri depends on certain hardware in the iPhone 4S that doesnt exist on any other iOS device. But what, exactly? The iPad 2 has the same CPU (A5) and same amount of RAM (512 MB), but no Siri, no text dictation. No one at Apple has an answer for this other than to say that Siri was developed alongside and specifically for just one device: the iPhone 4S. And as good as Siri is, I get the impression that Apple is far from satisfied with where it stands today. The Newton was killed by that egg freckles stuff it never recovered from the public perception that its handwriting recognition wasnt good enough. If Siri is any less accurate on older iOS devices than it is on the 4S, Apple isnt going to allow it.
Dont forget that theres a server/cloud-based backend that is required for Siri to function. I cant help but suspect theres some truth to this tweet from Mark Crump, speculating that Apple might be limiting Siri to the 4S simply to restrict the server load while the service is beta. There could be 100 million iOS 5 users by the end of this weekend; there will only be 1 or 2 million iPhone 4S users.
the simplest explanation I have heard goes something like this:
when you bought the iPhone 4, you didn't do it anticipating Siri. Apple does not "owe" you Siri (this comes out as admonishment, I know, but bear with me)...Apple spent money buying Siri, they spent money developing it, etc. Giving it to you for free won't earn them anything for that investment. Using it as a "ploy" to sell new hardware will allow them to recoup their expenditure
yeh it's pretty obvious it's a marketing trick. They want you to upgrade if you "WANT IT". Just like with their Macbook Pros, I love my 13 but there's no high-res antiglare sceen option, if you "WANT IT" they make you pay more money for a 15/17" ProHeyyyy, check it out, good old John Gruber himself decided to join the conversation!
Source: http://daringfireball.net/2011/10/iphone_4s
I agree with him that to say that it's for marketing reasons only is the "cynical" answer.
There's more behind it than that.
This info from the Siri Team:
The Fourier comb and Markov filter -- essential to turning a stream of words into a tiny handful of contextually-cogent bytes -- runs in one of the two PowerVR GPU cores that is in the newer A5. The 4S has extra links between the GPU output and the baseband chip so that the Siri application has its own dedicated connection to the cloud processing farms (currently, just the one in Philadelphia), piggybacked on the primary stream to and from the cell.
This shows it will only work on the 4S and maybe iPad 2S..
It's a conspiracy I tell you! Ignore what the developers say...they are just paid shills!!!'
Get a life losers....