Yep, they're required: Android Compatibility | Android Open Source
On that page, go to the "Current CCD" link on the left, then check out section 7.2.3. Pretty interesting read.
Type: Posts; User: KevinWorkman
Yep, they're required: Android Compatibility | Android Open Source
On that page, go to the "Current CCD" link on the left, then check out section 7.2.3. Pretty interesting read.
This list has a nice comparison of Android devices: Comparison of Android devices - Wikipedia, the free encyclopedia
Although it doesn't have any physical buttons listed... are you sure you're...