Boot process of embedded system is similar to PC from overview level, but slightly different from microscopic level.
Here's the boot process of an Android device:
PC-BIOS/BootMonitor, MBR and GRUB/LILO etc are all combined in one
Boot Strap Firmware called
init.S initializes stacks, zeros the BSS segment and calls _main() in
main.c initializes hardware (clocks, board, keypad, console) and creates Linux tags which in turns loads Linux Kernel image in memory.
Linux Kernel sets up the system, loads drivers and starts running the first process
init process involves setup of File System (mount points of
/sys etc are created at this point) and execution of
init.rc: It is boot-up script which uses Android-Specific syntax.
Zygot process in init.rc brings up
Dalvik VM and starts the system server.
All these are happened before Boot Animation is displayed.
For more details of processes, check out this article: http://www.androidenea.com/2009/06/android-boot-process-from-power-on.html