[OpenBIOS] Architecture

Tim Small tim at swift.amat.com
Mon Jul 5 11:27:11 CEST 1999


I am wondering if anyone has any recommendations for a general book which covers
x86 assembly, with a decent overview of x86 system architecture.  I've previously
only used 680x0 assembly.  So far, I've found this book in my local book shop:


Which looks quite good, but isn't exactly cheap!  I downloaded the PPro reference
manuals as PDFs from Intel, and although they seem pretty well written, they're
only really useful as a technical reference.

Kevin P Lawton wrote:

> > this BIOS, but I still think it is the way it should be done, since if=20
> > you want a 16-bit (old and crappy) IBM-PC compatible BIOS, you just keep
> > the one that is in your computer right now.
> >
> > So because of this I believe that your project won't benefit from my work
> > since you will need an IBM-PC compatible BIOS, right?

Well, not necessarilly.  As I've said - I don't know very much about the i386
architecture, but this is what I was thinking:

. Do minimum required in 16bit mode
. Switch to 32bit mode
  . Machine setup
  . Options/setup menu option
  . Insert your must-have feature here ;-)
  . Boot strap operating system

Wouldn't it be possible to add 16 bit support as a module which gets loaded at
bootstrap stage?  Either as a replacement 16 bit BIOS which is loaded by the
32bit one, how about trying to provide a 16bit interface with the 32bit BIOS
(although I'm not sure this is possible (32 bit disk drivers for DOS?), I don't
really know a lot about the x86, outside of 32 bit userland!).

> Actually, for booting a 32-bit OS, your BIOS may work.
> I have no problem having an optional 32bit only BIOS.
> We definitely a 16-bit one though for MS stuff though.

Yes, I agree - I seem to hit an average of about 2 irritating problems a week
caused by old and buggy PC BIOSs, and this is the only way I'll be able to flash
the lot into oblivion!  ;-)

> Actually, please join the developers list for freemware,
> and post something there about it.  16-bit stuff complicates

Hmm, development tools.  Can anyone see any obvious pitfalls in using software
like Bochs, and vmware for development and debugging?


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