Re: How does linux boot - best way 2 figure it out

From: Alvin Oga (aoga_at_ns.Linux-Consulting.com)
Date: 10/22/04

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    Date: Fri, 22 Oct 2004 00:53:12 -0700 (PDT)
To: Ritesh Raj Sarraf <riteshsarraf@users.sourceforge.net>

    On Fri, 22 Oct 2004, Ritesh Raj Sarraf wrote:

    > Now here is what confuses me !

    best way to learn how a PC boots..

    take the dumb/silly/antiquated BIOS and throw it away ...

            - now figure out how it boots

            - the CPU does jump to 0xFFFF FFFF as its first instruction
            after power on and reset and internal self-check

            what it does after that, is up to you
            ( what you put into the ROM at 0xFFFF FFFF aka BIOS )

            - you will first need to define your interrupt vectors
            - than a keyboard scanner so you can "tell it what to do"
            - than a serial console so "you can see"

            - than you want to read the disk sector
            ( the 512 byte at track-0, sector-0, head-0 (aka boot loader) )
                    - anything after that will be part of the filesystem
                    of how the heads and tracks are mapped

            - gazillion fun things to do in hw or sw or fw

    - the silly ami bios or phoenix bios or xxx bios restricts what
      you can and cannot do

    - for more fun, use a pdp11-34 or pdp11-70 or a 8080/6800
      and use the switches to load your "boot program"
      or the cassette tape ... or floppy disk or hard disks
      or nowdays, the usb stick or the network

    c ya
    alvin 

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