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{{WorkInProgress}}Technically speaking, there is no BIOS. Typical configurations of true embedded systems implement a bootloader instead. This software is executed by processor right after it comes out of reset. Like BIOS, bootlader is responsible of:# initializing the majority of hardware components - for example processor main PLLs and SDRAM controller# loading operating system kernel; once this step is completed, bootloader or any part of it is not involved anymore until next bootstrap.Bootlader usually implements a console - for example via UART port - that allows human operators to interact with the machine. This is extremely useful, for example, for maintenance operations and for development purposes.
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==Introduction==
[[File:Dm8148-block-diagram.png|300px|thumbnail|center|Naon SOM architecture]]
The first notable difference is about the integration level. By definition, system-on-chip such as DM8148, are designed to address embedded systems where footprint - in terms of PCB area and power budget - has to be minimized but, at same time, no significant compromise in performance is acceptable.
Reading of [[Deploying Embedded Linux Systems]] is recommended to complement issues here described.
==Where is the BIOS?==
==What about GPU?==
Modern PC graphics card integrates cards integrate a processor called GPU (Graphics processing unit) that is provided by accesses a dedicated SDRAM bank.
From the functional standpoint, on DM8148 graphics processing is performed by some blocks that are integrated in the chip. They are:
# Imaging Subsystem (ISS)
# Media controllers.
These blocks are tightly coupled with main general-purpose CPU (ARM Cortex-A8) and with SDRAMthrough a 128-bit wide 500 MHz internal bus called System Interconnect. All of these entities share the system SDRAM. SDRAM is managed by sophisticated DMM/TILER module that optimizes its usage and implements priority management.