Re: Booting with an "extended" floppy

[Thierry Laronde]

On Fri, Feb 02, 2001 at 05:08:50PM +0100, Thierry Laronde wrote:
> 
> There is a part of a floppy that is lost because
> of the formatting informations. Roughly, the "real" size of the media is
> 2MB. 

This formulation is, at best, ambiguous. In fact, the 1440 Ko come from
the 2 * 80 *18 *512 of the physical formatting. From these 1440 Ko a part
is lost with logical formatting (file system). So, without fs you can
use the whole 1440 Ko for data.

But physically, floppy readers and floppies can allow almost 1840 Ko by
playing not with heads (there are two), but number of tracks and
sectors. The problem is that, by default, BIOS finds the information
about floppy in the DDPT, where only "standard" formats are put.

Thus it seems (to answer my question) that if I want to use the whole
disk for data, without file system, I need, at least, to format the 
floppy with 18 sectors by track for the tracks where there will be stage2, 
and give GRUB other CHS parameters for the rest of the floppy, and
"trick" by giving the blocklist notation as if there was everywhere the
same CHS parameters (thus putting stage2 and menu.lst on the very first
tracks).

But, by now, using the "classical" 1440, grub allows us to use the whole
place for data, because it recognizes blocklist notation _and_ is able
to install itself with this kind of information (when LILO recognizes, 
AFAIK, only fs for installation, and blocklist for use --- and that's 
another point in favor of the GRUB ;).
-- 
Thierry LARONDE <address@hidden>
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