<P>Hi All ,</P>
<P>I am trying to understand the boot sequence of PC BIOS</P>
<P>I have got an rough idea it is as follows</P>
<P> 1. system power up and fetch up first from ffffff0 addr. <BR> 2. there is a near jump to code to get system in to flat or protected mode<BR> 3. then we can jump to further secod stage bootloader after neccessary HW init.</P>
<P> Plz Somebody correct it and explain it in detail .<BR> <BR>Second thing <BR> My BIOS image is ok abt 10 KB (suppose)<BR> and i have chip of 256KB So my image is like this</P>
<P><BR> ------------------------- lower most address(00000)<BR> Second stage bootloader : </P>
<P><BR> <BR> Protected mode init code :</P>
<P> </P>
<P><BR> Basic HW init Code : </P>
<P><BR> ..ffff0 jmp instruction to Basic HW init code( at bottom ) <BR> --------------------------- uppermost address(ffff...)</P>
<P>(Fig is reversed as per normal figures in books for memory )</P>
<P><BR> <BR>And I want to know where to place this small code in BIG chip</P>
<P><BR> ---------------------Chip start addr<BR> <BR> where to place my code in it ??? </P>
<P> <BR> </P>
<P> </P>
<P><BR> ----------------------chip end addr</P>
<P> </P>
<P>I think start and end of both will be in same direction so it may be like this</P>
<P> --------------------------lowest address for chip<BR> (free space with ff ff)</P>
<P> ------------------------- lower most address(00000)<BR> Second stage bootloader : </P>
<P><BR> <BR> Protected mode init code :</P>
<P> </P>
<P><BR> Basic HW init Code : </P>
<P><BR> ..ffff0 jmp instruction to Basic HW init code( at bottom ) </P>
<P> --------------------------- uppermost address(ffff...) both for chip and code <BR> <BR> </P>
<P>Plz comment and correct above information . </P>
<P>Thank you </P>
<P>Ramesh Chander</P>
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