Which iPhone, iPod touch and iPad models fully support iOS 4? Which models partially support iOS 4? For models that "partially" support iOS 4, which features are and are not supported?

Please note that all models that fully support iOS 4 also fully support iOS 5. Models that only partially support iOS 4 do not support iOS 5 or later versions of the operating system at all.

The initial release of iOS 4 fully supports all iPhone 4, iPhone 3GS and original iPad models. iOS 4 does not support the original iPhone and original iPod touch at all. No other iPod models support iOS 4 at all either.

Based on e-mail received, there is little confusion about the above, as it is rather straightforward.

However, Apple also notes that the 32 GB and 64 GB configurations of the third generation/Late 2009 iPod touch are fully supported as well, whereas the iPhone 3G, 8 GB configuration of the third generation/Late 2009 iPod touch, and second generation iPod touch are supported but "not all features are compatible."

Identification Help

If you are not sure which iPod touch you have, these models can be sufficiently identified for the purpose of iOS compatibility via model number in small type on the back of each device.

All configurations of the 2nd Gen and the 8 GB configuration of the 3rd Gen are model number A1288 and the 32 GB and 64 GB configurations of the third generation iPod touch, on the other hand, are model number A1318.

Everyi.com's Ultimate iLookup feature also can identify these devices by EMC number, order number (referred to as "model" in software), and their serial numbers as well.

Partially Supported Models & Features

Specifically regarding which features are "partially" supported, in separate support documents for the iPhone and iPod touch, Apple noted that all iPhone 3G and 3GS models and all second and third generation iPod touch models support "home screen folders" and the "unified inbox and threading for mail" features and these iPhone models also support Internet tethering, where available.

However, the iPhone 3G, 8 GB configuration of the third generation/Late 2009 iPod touch, and second generation iPod touch specifically do not support:

• Multitasking
• Data protection
• Bluetooth keyboard support
• Home screen wallpaper

Somewhat oddly, Apple's official support documentation does not explicitly mention that that the 8 GB configuration of the third generation iPod touch does not support the above, although marketing copy does correctly mention this limitation.

Unofficial "Jailbreak" Options

When reviewing the above list, most users likely understand that older hardware may not be capable of multitasking well or processing the encryption required for data protection, but home screen wallpaper in particular has hit a nerve with some. Semi-officially, as first reported by Gizmodo, Apple found that the "icon animation with backgrounds didn't perform well enough" on the "partially supported" models. Presumably, Apple found the lag time when using a Bluetooth keyboard to be unacceptable on these models as well.

As is typically the case, hardworking hackers quickly have jailbroken iOS 4 and when jailbroken it is possible to run the operating system with unsupported features to varying degrees of success on "partially supported" models. However, performance and battery life may suffer and the device may run hot as well. Even when running iOS 4 officially on the iPhone 3G and second generation iPod touch, some users documented substantial slowdowns compared to earlier versions of the operating system using iOS 4 features that Apple found to run at acceptable speeds.

As Apple, naturally, does not support jailbreaking, EveryiPhone.com cannot recommend that users of partially supported devices take this route, but the option exists for those who like pushing their hardware to its limits and can accept the consequences -- potentially both good and bad -- of doing so.