format b:
, then sys b:
. (I assume your floppy is B: in all that
follows.) You can also use mtools to manipulate a floppy image in a
file but you have to get the boot block from DR-DOS or FreeDOS to pass
to mformat.
dd if=
dev/fd1h360 of=floppyimage/.
floppyimage
can be manipulated as a DOS drive. The file you
want to edit is probably /etc/mtools.conf
. Alternatively, if
you know how, you could set up the loopback device and mount the
floppyimage as a DOS filesystem. Using mtools, you can copy
configuration files between the "floppy" and your host system and
edit them until you are happy with them.
ASK_BOOT
option with a short timeout and ANS_DEFAULT=ANS_NETWORK
.
This will enable you to boot the 286 normally if you need to fix
anything. All network cards, even the very old ones, should accept a 8
kB boot PROM. The compressed 16 bit images in Etherboot are under 8 kB.
Burn it into a PROM or find someone to do it for you. If you are using
a larger PROM, make sure you have burnt it in the right portion of the
PROM, or burn multiple copies in the address space to be sure. See
here for some things to watch out for.
mknbi-dos
program. Use the program to create a tagged image in the directory that
tftpd fetches from, typically /tftpboot
. The command is
probably: mknbi -x -x -r floppyimage -o /tftpboot/286boot
.
(The two -x
flags print out verbose information.) Check that
the /etc/bootptab
entry for the 286 specifies 286boot
as the file to load.
Tip: You can do a mdir directly on the netboot image if you use the offset parameter of mtools. In $HOME/.mtoolsrc, put
drive t: file="/tftpboot/dos.nb" offset=4096
Then you can do
mdir t:
4096 is the sum of the header size (512) and the startup segment size (3584). It may be different for other versions of mknbi-dos.
Caveat: For this trick, access other than reading only may not work. You may be able to rewrite things on the "disk" with mcopy, etc. but the declared size in the header will not get updated. If you wish to modify things you should work on the "disk" image, then rebuild with mknbi-dos.
Caveat: If you do your arithmetic you will see that the amount of XMS memory in the typical 1 MB 286 is not quite enough to hold the whole of the 360 kB floppy. After deducting the HMA, one is left with 320 kB of XMS. Provided you don't fill the "floppy" to the brim and use up the last "sectors", you should be ok. One way to be safe is to make a 320 kB "floppy" using 8 sectors per track instead of 9. And of course you could add more XMS and download larger "floppies".
Hint: Using an executable compressor like lzexe
or
pklite
might allow you to squeeze more programs onto the
"floppy". See a site like
Simtel.Net for such
programs.
Note: Of course, this technique works for 386s and higher. However you may want to consider netbooting Linux with an initial ramdisk instead of DOG.