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Boot Sequence: Difference between revisions
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== Early Environment ==
This early execution environment is highly implementation defined, meaning the implementation of your particular BIOS. ''Never'' make any assumptions on the contents of registers: They might be initialized to 0, but they might contain a spurious value just as well. This includes the FLAGS register and the SP register, you may not have a valid stack either! The only thing that's certain, is that the DL register holds the drive code from where your boot code was loaded.
The CPU is currently in [[Real Mode]]. (Unless you are running on one of those rare BIOS' which believe they're doing you a favor by activating [[Protected Mode]] for you. Which means you not only have to write code for activating protected mode on any ''other'' hardware, but should also add a test condition if it's already activated.)
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