The idea comes straight from the world of PCs : there you can if you want to wipe the system clean and install almost anything you like. From MS-DOS to Windows 2, Windows NT, OS/2, dozens brands and copies of Linux, Unix mutations the list is almost endless.
The onboard ROM on a "PC" will happily run whatever's on the disk or CD or DVD or other boot device. This is a 1970'as design which has not changed.
If you are missing device drivers for a certain device on PC then it (a) defaults to basic functionality (b) this device does not work at all but it is not always a stopping block.
I did not know what the obstacles are on smartphones. I was hoping to find and understand more details.
The MTK65XX chip set is an Arm CPU for which Windows have a new system. Some Chinese tablets now sell with Android or Windows.
Thanks for the explanations.
Well then think of it this way, Install XP on a computer. Take the hard drive out and try to boot on another one. It won't work unless you have all the drivers or extremely similar hardware.
I don't have a complete understanding of ARM, but I assume these Qualcomm SoCs have the TPM built in. Its almost the bottleneck with using WP8, but we'll have to wait for HTC to release a potential dual boot Android Windows Phone. Things will align sometime.
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OK Here is how PC/Windows works:
When Windows boots it uses a thing called "HAL" (hardware abstraction layer) - and whilst booting it tries its best to cope with a number of chipsets, disc drive controllers, and other core hardware components. This is done on the fly because there are only so many chipsets out there and the drivers aren't that large. If you boot Windows in debug mode you will see it loading one million drivers for hardware which you definitely not have - and when you actually install it it does the same - it does not ask you " what CPU / north bridge / south bridge / other DMA/ chipset / and everything else you have?". It just tries it all and loads what fits. The only things left out are whatever you can load later, eg specific sound card drivers, wifi, video card etc.
So this is a marriage between the PC's BIOS ROMs and the OS - so that with one single CD you can install pretty much anywhere. And this idea and technology has been around since the 70s.
For Linux/Unix/OS/2 and anything else on the PC the idea is pretty much the same: the BIOS has " started " the machine for you, and you simply run your "application" which in most cases is a complete OS!
For example I once wrote a memory tester that booted straight off the drive, without any other OS being present, it is that simple once you have the BIOS in place.
In my complete ignorance of how smartphones are made, I assumed that the hardware manufacturer of each phone provides a BIOS which can provide basic services like on the PC. Is that what we call the "bootloader" ? Looking at the "scatter files" it appears there is a whole lot of binary images before the "android" image.
Are these images the "hardware layer / BIOS" then? And can we consider the "android" image to be the actual OS?
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