ImageDisk project is canceled

[Scott Stevens]

On Thu, 22 Dec 2005 20:36:46 +0000 (GMT)
ard at p850ug1.demon.co.uk (Tony Duell) wrote:

> > 
> > On Thu, 22 Dec 2005 00:26:44 +0000 (GMT)
> > ard at p850ug1.demon.co.uk (Tony Duell) wrote:
> > 
> > > To get back to disk imaging, I may be stupid, but I do
> > > wonder if it's  actually possible to write such a program to
> > > run under linux or any other  multi-tasking system. 
> > > 
> > Since it's possible under Linux or one of the BSD Unixes to
> > completely compile out support for the floppy controller, it
> > should also be possible to pull said kernel code out, and
> > create a (super)user-mode module application out of it to do
> > whatever you want with the disk controller.  More of this sort
> > of thing should be done, in my estimation.  (my two cent
> > opinion, I know, since I should do-it-myself).
> 
> You are, IMHO, missing the point. Under linux, you have an
> ioctl() call  that lets you send any ocmmand bytes you like to
> the FDC. You can  therefore get that chip to do anything that
> it's capable of. And that  call takes care of setting up the DMA
> controller if you need it, making  sure the DMA buffer doesn't
> cross a page boundary, and all the other  nasty little details. 
> 
> Actually sending a ReadID command is not a problem.
> 
> The problem is that the ReadID command reads the next sector ID
> to come  round to the head. The only way (that I can see) to
> make sure you've not  missed any is to keep on sending ReadID
> commands (and getting the  results) until you get the same ID
> again that you got from the first one  -- i.e. the disk has gone
> round once. 
> 
> The problem on a multi-tasking OS is that your task might be
> switched out  half-way though this. You might therefore miss a
> sector ID entirely. And  how ever many times you repeat it, you
> can never be sure you've not been  unlucky and missed the same
> one each time.
> 

It's not difficult to boot linux in single user mode.  And then to
think of it as an infinitely flexible MS_DOS type of OS.  After
you've gotten the image safely stored somewhere, boot it to a time
sharing mode to move the image around and/or explore it.