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

[Alvin Oga <aoga@ns.Linux-Consulting.com>]

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