Today I have received my first Android device, to be more precise a GOClever Tab A102.2 tablet. I have noticed that it runs as operating system Android 4.0.4 so I though why not update it since the latest one is 4.2? I went to Settings > About > System Update however it asks for a update.zip file which I have to place in NAND or SD card.
Searching through the internet I have found that some devices connect to the internet and check for updates when prompted while others need to be updated with vendor specific versions (I guess that's the case for me).
Now I wonder, why do some devices need to be updated with vendor specific versions? The way I see it, Android is just an Operating System and thus not tied to the device so theoretically if I wanted I could ditch it in favor of some other operating system (say a linux distro) so whether the update comes from the vendor or not should be irrelevant.
Also, can vendor specific versions of Android be updated (through some other means) even though the vendor didn't release an update for it?