[Gllug] Building a system from scratch

Dylan Brewis dylan at exoletus.fsnet.co.uk
Sat Apr 20 00:09:30 UTC 2002

Cheers for the pointers, but my quandary remains.

I remember the Cambridge Research (I think?) 4-bit machine screwed to a 
wooden board; tapping hex-coded machine code directly into memory and running 
the program with something akin to (hex-code of) JMP xx.

Then there was a Commodore PET; many hours spent POKEing values to screen 
memory for sprites!

VDU statements, *FX, OSWORD

Implementing 'overlays' in BBC Basic and raster-timed colour tricks in 6502 

I still have my first hard drive (a 'Winchester'); albeit opened up to show 
the inner doings to an incredulous drunken (maybe stoned) audience at some 

When my father's IBM PC arrived, it worked WITHOUT a floppy! No 
floppy=cassette loading of programs, put in a boot disk and get DOS.

Oh, the liberation! 64k (if u were lucky, 128) to 640 in one fell swoop 
(well, if u decided to upgrade)

Am I rambling? Maybe it's the Gin!

On a windose system, I know what happens between power-on and login dialog or 
usable desktop. I've read the powerup to bash howto - it tells me what 
happens. But Win95 loads EMM386.whatever as a DOS driver because of legacy 
protected(/real?) mode Intel stuff. The equivalent information is not in the 
howto (or have I just been blind to it?)

How does Linux (for that mater *nix) relate to the BIOS? Is it ignored after 
the POST and bootstrap, or does the Kernel hook it up later? (for example) 
When I wanted to manipulate the parallel port under W, it was easiest to call 
a 'DOS-mode' driver (of sorts) to do the peeking and poking - is the 
equivalent true in *nix (I don't even know where to look for the underlying 
info to work it out!)

I feel, it's almost proud, but words are falling asleep as the Gin keeps 
arriving. Still, I've gone from 1 Win98 machine and a Win95 laptop to a five 
client Linux network with server and gateway in a year. As a hobby. Got round 
NFS, automount, NIS, blah blah. Haven't managed to print yet (but done some 
CD writing, audio sampling and scanning. Hey, who cares about the details?

I might, if I were naive, say "what is the difference between the kernel, a 
module, and a daemon". In reality I suppose, "what issues/facts/situations 
lead a programmer to decide between a kernel patch, a module and a daemon." I 
can think of NFS as an example. If I read the stuff right, it's gone from 
daemons to kernel/module, yeah - so an individual function can be implemented 
in many ways as many system levels. I know how to decide between a background 
task (I knew them as TSR's) and a (virtual/DOSmode) device driver. (in the 
end the answer seems to be "Don't use Windows."

I'm looking for something like this...:

"The core of a Linux system is the Kernel, which must necessarily do this. 
For the sake of portability, these functions are often implemented as 
modules, but you can build a monolith...

"Once the kernel is loaded it has to do this because and then it can do this 
so that this can happen. Memory paging is implemented like this because it 
relates to swap space and hard drives thusly."

I don't want to know this stuff when I wake up tomorrow morning - I expect to 
be learning more the day before I die (bigger lessons to learn THAT day!) but 
WHERE OH WHERE is the information. It's a fscking swamp and I'm drowning!

On Thursday 18 April 2002 14:13, Dylan Brewis wrote:
> Hey guys,
> I *upgraded* to Linux about a year ago, and the learning curve seems to 
> levelled out at last. I'm not at a point where I want to go from using a 
> distro (SuSE7.3 at present) to building a system from the ground up. I 
> the only way to get a feel and understanding of how the system really works 
> is to do that.
> I've checked out LinuxFromScratch, but to be honest that's no more 
> informative than footling around in the man pages: it says 'install these 
> packages in this order and with these options' which is just about a manual 
> installation so far as I can see.
> So, can anyone point me to some decent resources - books or on line - which 
> will help with the 'how it all fits together'; 'what the options mean'; and 
> 'why things work how they do' questions? I've had several trawls thru 
> LDP etc..., but to be honest I'm caught in the *to study a subject, 
> understand it fully before you start* paradox!
> Cheers!
> Dylan
> -- 
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