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ADDHELP.TXT
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1994-09-03
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ADDHELP.EXE : adds help
screens to .COM files
version 1.0 August 1994
written by John Nurick
70162.2472@compuserve.com
Description
===========
ADDHELP.EXE modifies .COM files so that they display a help
message when invoked with the standard '/?' parameter, just
like standard internal and external DOS commands.
This manual also gives instructions for adding a `/?' help
screen to a batch file.
Contents
========
Background..........................................2
Using ADDHELP.EXE...................................2
Instructions ....................................2
Limitations and Caveats .........................3
Patching ........................................4
Self-checking programs and anti-virus systems ...4
Help Message Hints ..............................4
Adding Help to Batch Files..........................5
Disclaimer..........................................5
ADDHELP.EXE INSTRUCTIONS 2
Background
==========
There are so many useful little utility programs that it is
almost impossible to remember what they all do, let alone the
command line parameters and switches they need. A few offer
help if you invoke them with no parameters, or with a
particular parameter (e.g. /?, /h, h, ?, -h, /help). Others,
especially TSRs and mini-programs created from DEBUG scripts,
may ignore such parameters and do unexpected things to your
system.
DOS 5.0 made a start in clearing up this mess. All
standard DOS 5.x and 6.x commands, internal and external,
display a brief explanation of their use and syntax if they
are invoked with the /? switch. ADDHELP.EXE lets you bring
most .COM utilities from other sources, including the ones
you create from DEBUG scripts, into line with this convention.
Using ADDHELP.EXE
=================
ADDHELP will modify practially any .COM file so that it will
display help information when invoked with /?. Almost all
programs will work absolutely as normal after modification:
see *Limitations and Caveats* below.
ADDHELP.EXE takes a .COM file and an file of ASCII help
text and creates a new .COM file with code to display the help
message or run the original program. ADDHELP can also dis-
mantle a file it has modified and recreate the original .COM
and help text files.
Syntax:
ADDHELP /A[dd] STANDARD.COM HELP.TXT MODIFIED.COM
ADDHELP /E[xtract] MODIFIED.COM HELP.TXT STANDARD.COM
ADDHELP (display syntax message)
ADDHELP /? (Display help screens)
STANDARD.COM [pathname of] program without help facility
HELP.TXT file containing help text
MODIFIED.COM [pathname of] program with help facility
ADDHELP.EXE INSTRUCTIONS 3
Instructions
(1) Suppose you want to add a /? help facility to the utility
STANDARD.COM (see "Limitations and caveats" below for
information on what kinds of program may not be suitable
for ADDHELP).
(2) Prepare an ASCII text file containing the help information.
Let's call it HELP.TXT. This should not exceed 20 to 23
lines, to allow room for the DOS prompt. If it displays
nicely with the command TYPE HELP.TXT, it will work.
(3) Issue the command
ADDHELP /A STANDARD.COM HELP.TXT MODIFIED.COM
ADDHELP will display progress messages (or error
messages!). If all goes well, MODIFIED.COM will behave
*exactly* like STANDARD.COM except that when you issue
the command MODIFIED /? it will display your help screen.
Suggested working practices
Keep the original .COM files in one directory or disk, and put
the modified ones in another, and the help screen files possibly
in a third. Alternatively, rename the original file first, e.g.:
REN STANDARD.COM *.C_M
ADDHELP /A STANDARD.C_M STANDARD.HLP STANDARD.COM
Limitations and Caveats
The original and modified files ("STANDARD.COM" and "MODI-
FIED.COM") must have different filespecs. If they are in the
same directory they must have different names, but if you
specify different drives or directories they can have the same
name. You must specify the full name (including extension) of
each file. With this exception, ADDHELP output files will over-
write existing files of the same name without warning.
ADDHELP has worked on every .COM file on which it has
been tested. But it has not been tested on and is not recom-
mended for .COM files which act as loaders for large programs
(e.g. WIN.COM in Microsoft Windows or WS.COM and WORD.COM in
some versions of WordStar and Microsoft Word). ADDHELP will
not create a file if it would exceed the 64k .COM limit.
Do not use ADDHELP on programs that modify their own .COM
files in the course of ordinary activity. See "Patching"
below.
ADDHELP.EXE INSTRUCTIONS 4
.EXE files cannot be modified in the same way as .COM
files. To confuse matters, files with a .COM extension can
sometimes be in .EXE format. ADDHELP can identify most .EXE
format files and will refuse to modify them.
Patching
Special care is needed when patching a program modified by
ADDHELP (e.g. to change colours or hot keys).
MODIFIED.COM contains all the code and data that is in
STANDARD.COM, but not all of it is in exactly the same
locations in the file. Consequently, attempts to patch bytes
at particular locations may have unpredictable results. This
is true whether you are patching with a disk editor, a
separate configuration program, or (and especially) a self-
modifying program.
You can avoid this problem by using the ADDHELP /Extract
command line switch, which extracts code and data from MODI-
FIED.COM to restore copies of STANDARD.COM and HELP.TXT. These
can then be altered as necessary before being re-combined into
a new version of MODIFIED.COM by running ADDHELP in the usual
way.
The copies of STANDARD.COM and HELP.TXT produced by
ADDHELP /E are identical to the originals, except that if the
original STANDARD.COM was shorter than 32 bytes, the extracted
reconstructed version will be padded out to 32 bytes.
Self-checking programs and anti-virus systems
Some programs check themselves when they run to detect unau-
thorised changes such as those made by a virus. They should
also detect the changes made by ADDHELP. If this happens,
there is nothing for it but go back to using STANDARD.COM.
If you use an anti-virus system that keeps track of legal
executable files, you will have to register MODIFIED.COM with
the virus checker.
Help Message Hints
Use any editor or word processor that can produce plain ASCII
files to create your help text. To save disk space, keep the
text as short as you reasonably can, and make sure it fits in
23 lines or fewer so that the beginning does not scroll off
the screen. It is a good idea to include copyright details of
the original program and the fact that it has been modified by
ADDHELP.
ADDHELP.EXE INSTRUCTIONS 5
Adding Help to Batch Files
==========================
It is easy to make a batch file display a help message in
response to the /? parameter. For example:
@echo off
rem DEMO.BAT
if "%1"=="/?" goto HELP
rem Put batch file commands here!
echo Hello World!.
pause
rem End of batch file commands
goto END
:HELP
rem Put echo commands for help message here
echo.
echo DEMO.BAT
echo Demonstrates use of /? help switch in a batch
file.
echo Syntax: DEMO (runs main batch code)
echo DEMO /? (displays help message)
echo.
:END
Disclaimer
==========
The author gives no undertaking or warranty as to the per-
formance of ADDHELP.EXE or its suitability for any purpose
whatever, and accepts no liability for any loss or damage
resulting directly or indirectly from its use.
On the other hand, he doesn't ask anything from its users
either, except perhaps to be told of any bugs they find or
improvements they make.
ALWAYS KEEP BACKUPS OF EVERYTHING!!!