Mail Archives: opendos/1997/04/01/12:23:08
On Fri, 28 Mar 1997, Colin W. Glenn wrote:
> OpenDOS should also support single-stepping the boot as well.
???
It *does* already (since Novell DOS 7)! (Though, I think it's not
pretty documented, at least not in the Novell docs.)
Press <F5> or <F8> while the kernel shows the startup message
"Booting DOS...". These keys work very similar as under MS-DOS
(alternatively, under NWDOS and OpenDOS you can press just the
<Shift>-key, avoiding annoying beeps caused by a keyboard buffer
overrun), but:
- Currently, you cannot enter <F5>/<F8> mode, while showing boot
menus (you can do that under MS-DOS/PC-DOS).
- In single-stepping, you will than be asked (Y/N) (assuming an
English localized kernel as it is with OpenDOS) for (almost) any
CONFIG.SYS directive (similar to ? before a line).
In foreign countries (and with no keyboard driver loaded at this
stage), this might be very annoying to some people, e.g. here in
Germany you will be asked for '<Y>es' instead of '<J>a', but
actually have to press the <Z>-key, which on our German QWERTZ
keyboard layout is in-place of the <Y> on US QWERTY keyboards.
Fortunately, Novell had already implemented a cure for this, but
failed to document it:
Using the undocumented YESCHAR= directive, you can select the
character you want to be asked for instead of <Y>, e.g. YESCHAR=J
would fix these problems for Germany.
Note, that as with all other directives (except for SWITCHES=),
the YESCHAR= directive takes effect *after* it is parsed by
IBMBIO.COM, and that's in exactly the order, the CONFIG.SYS file
is interpreted (which is completely different under MS-DOS/PC-DOS,
where the CONFIG.SYS will be compiled in some respect). However,
it is much more flexible.
- If you use the SWITCHES= directive (which is also undocumented
under Novell DOS and OpenDOS), the behaviour may change,
depending on the switches you use and the location of the SWITCHES=
directive in the CONFIG.SYS file. (I would call this a bug, but as
with all those things, it's also a feature. If we change it - and
we should, since it's a remaining security loophole - we should make
it selectable by, of course, one more option.) For equally results
as under MS-DOS, always place SWITCHES= in the very first line of
CONFIG.SYS!
- Using a 3rd party command processor like 4DOS, you cannot single
step through batch files like AUTOEXEC.BAT, since single-stepping
is passed through to COMMAND.COM by some undocumented function,
which is not supported by 3rd party replacements.
This was changed with one of the latest Novell DOS 7 updates
(I think it was silently introduced with Update 14 or Update 15/1),
and currently cannot be found in Caldera OpenDOS 7.01: A new MS-
DOS a-like COMMAND.COM option /Y was added and now single-
stepping is passed to the command processor by giving this option.
(Of course, we should add on this by giving the YESCHAR to the
command processor, e.g. /Y:J...)
Hey, this once more was a heavy ride on undocumented Novell DOS and
OpenDOS... ;-) For more details on these switches and features,
have a look at my NWDOSTIP.TXT file (from MPDOSTIP.ZIP).
Bye,
Matthias Paul
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