On Tue, 4 May 1999, Alistair Riddoch wrote:
> David Murn writes:
> >
> > On Mon, 3 May 1999, Alistair Riddoch wrote:
> >
> > > The problem is that the only disk driver we have working yet is the one
> > > that uses BIOS routines to access the disk. After DOS is loaded the int 13h
> > > entry in the VII which initially points to this BIOS routine is replaced.
> > >
> > > BootELKS gets round this by having an image of the VII before DOS was
> > > loaded, and loading this into the VII before the kernel is started, giving
> > > the kernel access to the BIOS routines.
> >
> > Oh, in that case it's easy, we simply write a little chunk of code to put
> > at the start of a disk, which simply copies the VII to some point later in
> > the disk, to be retrieved by a DOS program.
>
> The problem is that with palmtops which boot from ROM we don't have access
> to the machine until DOS has started. There is no boot disk, so we cannot
> put any code on it.
Here's what I'd like to see with booting ELKS from a palmtop:
1) boot to DOS, with as little in-memory as possible (this is 620 Kbyte or
so on an HP200LX, I believe)
2) have a boot loader that allocates all of the available memory from DOS
in a single block
3) use that block as the memory that ELKS can play in
4) only change the interrupts you need to (keyboard, serial, timer), and
possibly chain some of those (like the timer interrupt)
With a system like this, you could even exit ELKS to return to DOS if need
be. Unfortunately, I have no idea how much effort this would be to
create. I suppose I can start looking at the code when I get back home
(next week), just to get a feel for the scope.
As a plus, you could use the DOS services in the same way that you can use
BIOS for operations today. This would make it possible to use a DOS file
as an ELKS boot disk, which would be nice for the HP200LX, for instance,
which uses its memory above 640 Kbyte as a proprietary persistant RAM
drive. You could even access Stacker drives and the like.
Hmm...maybe ELKS would be better marketed as Unix-on-FreeDOS?
Shane
