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Date:	Fri, 12 Mar 2004 14:59:35 +0100
From:	Matthias Paul <Matthias DOT Paul AT post DOT rwth-aachen DOT de>
Subject:	FYI: JP Software removed support for startup option /Y in 4DOS
To:	opendos AT delorie DOT com
Message-id:	<000c01c4089d$01b8ea40$c03dfea9@atlantis>
Organization:	Aachen University of Technology (RWTH), Germany
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Reply-To:	opendos AT delorie DOT com

[Somehow, the mail seems to have vanished on it's way into
the list, so I am resending it.]

Hi folks,

I assume that quite a few DOS users inhere use JP Software's
otherwise excellent command processor 4DOS.COM as replacement
for COMMAND.COM or FREECOM.

It happens that with one of their recent builds of 4DOS 4.50
(most probably 124 -- the current build is 125) they silently
but deliberately removed support for the startup option /Y in
order to invoke the batch file debugger.

/Y is supported by COMMAND.COM since MS-DOS 6.2, PC DOS 6.3, late
issues of Novell DOS 7, and by DR-DOS 7.02 and higher, and (like
the earlier /D) is used to communicate the user selected skip-
(F5) and single-stepping-(F8)-modes from the DOS BIOS to the shell.

If you had pressed F8 during startup and were single-stepping
CONFIG.SYS, the DOS BIOS would automatically add a /Y to the shell
command line, so that the invoked shell could continue to single-step
through AUTOEXEC.BAT. In particular, this is important when you
cannot manually edit the configuration files, for example, during
CD-ROM boot or such.

(NB. Similar means also existed in the initial version of
Novell DOS 7 and in OpenDOS 7.01, but they didn't used the
command line interface, but communicated the status of the
boot mode through special settings retrieved via the pre-
environment. This internal interface is still supported in
all recent issues of DR-DOS and COMMAND.COM, so that you can
easily mix different kernel and shell versions. Unfortunately,
4DOS does not query this internal interface, although this
would have some advantages as it is more flexible and can
report some further sub-modes to the shell so it could be
even more seamlessly integrated than just using /D and /Y.
Also, this interface could still continue to work, even if
support for the option /Y would be permanently removed in
4DOS. On the other hand, this will only work for the DR-DOS
family, as MS-DOS/PC DOS only support the /Y and /D trick.)

/Y can also be used to single-step normal batchfiles, and
according to Rex Conn, head of JP Software, several system
administrators did complain that users would 'misuse' /Y in
order to bypass some stuff in the startup batchjobs, hence
support for this option was silently removed in one of the
most recent builds (it's still in the help for build 124,
but doesn't work there any more, in build 125 it has also
been removed from the help).
Unfortunately, that they are thereby breaking an IMHO vital
part of DOS compatibility and cause significant inconveniences
to users who have to single-step their startup files in an
emergency case does not seem to occur to them it seems...

So, if you are a user of 4DOS, this mail is intended to inform
you of this modification, which otherwise may escape you until
the next time you have to single-step the configuration files
in an emergency case and find it to be no longer working...

If you do not agree with the change, I would like to encourage
you to voice your opinion in JP Software's support forum and
ask them to reenable the previous behaviour, just as I and several
other users did - so far without success, though. Or, if
you prefer that this option be removed, you can also state
this there. After all, that's democracy... ;-)

Otherwise, I'd like to suggest that you keep hold of the last
4DOS build which still has this option enabled. (I think, it
was 4DOS 7.50 build 122, but right now I am not completely sure
about this, as I didn't had any time to follow and update every
new build in the past few months myself, so I will have to find
out myself now as well.)

Hope it helps to keep you from stepping into a trap by "upgrading"
to the latest build.

Greetings,

 Matthias

-- 
<mailto:Matthias DOT Paul AT post DOT rwth-aachen DOT de>; <mailto:mpaul AT drdos DOT org>
http://www.uni-bonn.de/~uzs180/mpdokeng.html; http://mpaul.drdos.org

"Programs are poems for computers."

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