-iPhone OS and Mac OS X are subsets of OS X, imagine a third way taking both sides into account.
Absolutely. But, as long as it allows me to:
1) install apps without oversight from Apple (ie. direct download and install, not limited to the iTunes store)
2) run apps in the background
3) use Bluetooth HID and FTP
4) use USB interface devices (keyboard, mouse, trackpad, trackball, etc.) and USB storage devices
5) has support for video out and/or remote desktop as the server* and/or Redfly
(* server meaning "display the tablet's screen onto my desktop computer running a VNC or remote desktop client/viewer")
-dual core ARM CPU with some homebrew magic makes sense for power efficiency (everybody will moan if it only has 2h of battery life) and help the tablet stay cool. Ever pushed an Atom netbook to its limits? Felt the heat? And it might be more powerful than an Atom.
An ARM based CPU would be a very good start, yes. And the underlying kernel and OS already run on ARM (on the iPhone and iPod Touch), so the hard part is already done. This "3rd variant of OS X" would only need to have its upper layers tailored to the CPU.
-Remember Steve Jobs insisting on the fact that OS X is CPU-independant by design during the Intel switch keynote? Recompiled relevant apps could still be adapted to a new GUI framework.
It is. The underlying OS for OS X has had incarnations on:
- Motorola 68k family (NeXTstep 1, 2, 3, and 4)
- (a processor family whose name I have forgotten, that was going to be the basis of the the NeXT workstations post 68k family; cancelled when NeXT stopped being a hardware company)
- x86 family (NeXTstep 3, 4, and current Mac OS X)
- Sun Sparc family (NeXTstep 3 and 4)
- HP PA-RISC family (NeXTstep 3 ... maybe 4)
- Power PC family (early Mac OS X)
- ARM family (iPhone OS X)
CPUs already. Adding a new variant of ARM wouldn't be a colossal effort. And, luckily, NeXT's engineers did the right things, way back in the early 1990's, to ensure that adding CPU architectures wouldn't require a complete overhaul nor re-tooling of the platform. Even the recent "universal binary" feature of Mac OS X, as it transitioned from PowerPC to x86, wasn't a new feature at all. "OS X" has had that feature since the early 1990's, when you could use 1 NeXT platform to build, debug, and deploy a single "FAT" binary for 4 CPU platforms (68k, x86, Sparc, and HP PA).
Probably only Linux and NetBSD offer a wider range of hardware platform support than OS X's family of OSes has... and OS X's support is much more uniform and transparent than either Linux or NetBSD's.