11 Jan
2006
11 Jan
'06
3:07 p.m.
On Wednesday 11 January 2006 05:59 pm, Scott Stevens wrote:
On Wed, 11 Jan 2006 17:07:15 -0500
"Roy J. Tellason" <rtellason at blazenet.net> wrote:
I would tend to agree with this.
On Wednesday 11 January 2006 12:16 pm, Dave
Dunfield wrote:
Yes. There are some folks who are using linux to do realtime control,
but it takes some kernel hacking, and I am not up on the details of what
needs to be done to accomplish this at the moment. Look on linuxcnc.org
for more info on that...
My feeling on the matter is that when a computer is being used to
image and/or salvage data off of non-native disks, it is being
used as a piece of test equipment, not as a general purpose
computer. As such, it's 'legitimate' to run it as root, dig deep
into the driver hierarchy and kernel, etc. >
Observations about the floppy interface in NT/2K/XP are accurate.
> The native floppy driver is hard-wired to expect Microsoft-format
> floppies, even to having the boot sector information being
> critical. (Try clobbering a boot sector and then reading an
> otherwise valid diskette--you'll get a general failure). Sydex has
> quietly made a tidy side business of licensing a kernel mode floppy
> driver for NT and 2K/XP (in addittion to Win9x VxDs) to firms
> needing CP/M (using a DLL interface) or other direct access
> (driver access) to "alien" diskette types. We're currently
> working on a Vista driver. Operations like "sync to the index hole
> and read a bunch of IDs nonstop" are atomic functions with the
> driver.
>
> While this will keep most of our customers happy for the short
> term, I expect that floppy-less Windows PCs will shortly become the
> rule. We're actively investigating the possibility of a USB add-on
> floppy drive that will be able to handle most formats. I also
> anticipate that FDC chips will become rare birds, so implementation
> of some sort of FDC through software of FPGA would seem to be the
> wise course. I've investigated downloading special firmware into
> floppy USB chips, such as that used on the Teac FD-05U, but Teac
> has not been forthcoming on the controller chip details being used
> in any particular model.
Stuff like this makes me *SO* glad that I don't run any m$ crap later
than 98, and that I run mostly linux, not to mention not having
gotten rid of any of my CP/M boxes...
I expect that Linux would have similar issues. Basically any OS which
uses protected mode will likely disallow application program direct
access to system resources, and not expect interrupts to be generated
from elsewhere. Any general purpose multiprocessing OS, will likely
have issues with real-time critical operations as well. I was corresponding with someone trying to get
ImageDisk running DOSemu
a while ago, and ran into some of these issues. I pointed out at that
time that the only "proper" way to do a program like this under Linix
or any other "real" OS would be to put the analysis function and
flexibility to read foreign formats into the floppy driver, where you
do have direct access to the hardware, and each phase/operation can be
initiated in hard real-time by the interrupt generated by the
completion of the previous phase ... this is exactly what Chuck is
describing with regard to his enhanced drivers.
I haven't gotten into programming under linux to this extent, but I'd
guess so. There's "user space" and "kernel space", and all
sorts of
other things to consider. At this point in time there are _so_ many apps
that I find useful that I haven't yet gotten around to poking around on
the programming side of things... :-) A lot of the real power of a diskette
imaging/analyzing system will be deep
within the system. So making distinctions between 'user space' and
'kernel space' might be interesting, but ultimately are irrelevant.
Maybe relevant in terms of what you have to do while programming, though.
Just a guess, as I haven't ventured there yet.
A piece of test equipment is designed for a specific
purpose, and a computer
repurposed to something like this will be as well.
Yup.
Only problem is, I really don't have enough room here to stick another
machine dedicated to reading CP/M disks, so I guess one of my other boxes is
going to have to do...
--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, a critter that can
be killed but can't be tamed. --Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin