warning
The information on this page is for expert users only. The directions you can read here instruct
you on how to edit a binary executable. Editing binary executables can cause system crashes and loss
of information on your computer if not executed correctly. Follow these instructions at your own risk.
I strongly advise you NOT to follow these instructions because doing so is probably an infringement of copyright law, or
will at least be in conflict with the maker of the binary executable.
The information given here can be applied to -any- executable that has been compressed with the lzexe
utility. ZZT is just an example.
Now to the good stuff
introduction
ZZT contains a large number of standard messages and strings. These messages are
embedded in ZZT and cannot be changed by the user with ZZT OOP programming. However, there are cases
where a programmer doesn't want to see certain messages, or the standard messages are not really
appropriate in his game. Let's face it: "You don't have any of ammo!" doesn't sound so cool in a gangster type game.
Certainly not when it's been used in a hundred western type games before.
You have a moral obligation when you start spreading altered versions of ZZT. The purists among is
argue that spreading mutilated version of ZZT will only cause a big mess and is basically bad form. I personally
subsribe to this opinion as well.
Please note that the gamer is always in control of which zzt.exe he uses to play your ZZT game. You can only
advise the gamer to use an altered version.
When ZZT was built its main distribution channel was the Bulletin Boards which was basically the precursor to
the internet. Communication speeds were low (1200 baud, 2400baud, 9600baud, etc) and downloading files was a pain.
When Tim Sweeney made ZZT he wanted to make his executable as small as possible and he probably wanted to protect
his sources. So, he used a very popular tool in those days for compressing executables. This tool was called lzexe and
it compressed the executable and placed a tiny decompression routine at the end of the file. As soon as the executable
was started the original source was uncompressed using this routine. This technology is much like today's self-extractors,
with the added feature that the extracted executable was started automatically. If you want to know more about lzexe
and the compression algorithm it uses, go to www.stud.enst.fr/~bellard.
what you need
You will be downloading some stuff that is compressed using WinZip. Get a shareware version of
it here.
You need the standard ZZT package containing the ZZT.EXE executable file. This is
the one we will be changing. You can download ZZT from either one of these web sites:
Next, you need a tool to compress and uncompress the ZZT.EXE file. It is called unlzexe and you can get that here:
lzexe91e.zip for Dos/Windows (85Kb)
You also need an editor that will allow you to change strings and bytes in ZZT.EXE. You -could- use standard editors like
vi (linux/unix) or edit (dos) or even notepad (windows), but please take care. Editors will sometimes add stuff to your
files, thinking it is a simple text file. Remember that we're editing a binary executable here. We must be careful
about what we change. Altering stuff that's shouldn't be altered (like actual programming) will probably result in crashes
and possible loss of data.
The editor I use under windows is WinVi. This is a free vi editor for windows that is really, really good. You have to know
vi, though. If you don't know how to use vi, then please find something that you can use. You can get WinVi at
www.snafu.de/~ramo.
Download and unpack all these files into one directory. You now have all you need to alter strings in ZZT!
what you do
Before you do anything, make a backup of your ZZT files. Then, you execute the following command:
unlzexe zzt.exe
lzexe will have created the following files:
ZZT.EXE - 96,080 bytes
ZZT.OLZ - 47,764 bytes (this is a copy of the original)
Start your hex editor and load up ZZT.EXE. You can now search for the string you wish to change. I looked for the "You don't
have any of ammo!" message and it looks like this in WinVi:
You can edit this string, but you have to keep in mind that the string you put in there must be the same length as the
original or ZZT will crash!! I changed the string into "...loser...". It looks like this in WinVi:
When you're done editing just save the zzt.exe file. It should still be the same size as before (96,080 bytes).
If I loaded up a game and started shooting on a board where I had no ammo, it would come out like this:
If you're satisfied with the result, you can compress zzt.exe back again using the command:
lzexe zzt.exe
The ZZT.EXE that was there is renamed to ZZT.OLD and the current ZZT.EXE is like the one you've come to know and love, but
with your own messages.
So that's basically it. If you need help you can email me here.
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