Re: [ECOS] PC boot image for 720k FDD

["Patrick O'Grady" <patrick at softprocess dot com>]

Most OSs actually write the diskette geometry onto the first sector of the
disk.  hmm... yes, here's how MS/DOS does it:
http://support.microsoft.com/support/kb/articles/Q140/4/18.asp.  Check out
the FAT boot sector section...  you can see that the diskette geometry is
stored there.  Seems like it shouldn't be too hard to add this little
structure to the beginning of the .bin file, and have the code itself use
these parameters to determine how to read the rest of the file.  Those
parameters could be controlled thru configuration or patched before
writing to the floppy...  (Would love to do this myself, but I *still*
can't compile eCos on my BSD system..)  Hope this helps...

-patrick



On Tue, 18 Jul 2000, Bart Veer wrote:

> >>>>> "Vlastimil" == Vlastimil Masek <rur@altavista.com> writes:
> 
>     Vlastimil> Is there any way to make PC boot image for 720kB FDD.
>     Vlastimil> The current floppy disk boot code "gdb_module.bin"
>     Vlastimil> seems to be hard-coded only for 1.44M floppies.
> 
> I suspect that none of the developers of the i386 PC support had
> access to a machine that still used a 720K floppy drive.
> 
> After a very quick glance through the source code, it looks like
> most/all of the relevant code lives in the hal_cpu_init macro in
> hal/i386/pc/<version>/include/platform.inc. To add support for 720K
> floppies you would want to add a configuration option, and then modify
> this initialization macro to cope with different types of floppy
> drive.
> 
> Bart Veer // eCos net maintainer
>