Debug mode in SCI32 games

kelmer This is not exactly SCI programming related but... sort of.

I've heard of a debug mode in some sci32 sierra games (LSL7 and torin's passage to be exact). Something like creating a blank file named classes or something. Is there any truth in this? If it's so, how exactly can one get access to it?

kelmer wrote:

This is not exactly SCI programming related but... sort of.

I've heard of a debug mode in some sci32 sierra games (LSL7 and torin's passage to be exact). Something like creating a blank file named classes or something. Is there any truth in this? If it's so, how exactly can one get access to it?


This is true. I heard about it an tried it a long time ago. It worked, but I don't remember how to do it. I'll try the classes thing, sounds farmilliar. I just need to install LSL7 first.
Lars Skovlund The classes thing is correct - however, since it is implemented in
script code, it doesn't work on all games - only those that
include the debug script (which, granted, are most of them).
LSL7 works.
Omer Mor It works in SQ6 & SQ6DEMO too.
It has an extensive debug, similiar to the one found in QFG2. you can even edit the room's path polygon, and save it to file in SCI1 language!
All you need to do is create an empty file named CLASSES in the game's directory, and then when the games starts it asks you where you want to start the game (you choose a room from a list).
In the game you can press anytime the '?' key and get the debug menu.

There is also a debug mode in PQ3 I once read about.
What you need to do there is delete/rename the "version" file, and then when the game starts it asks you on which day you want to start, and some other questions. However, I didn't find any debug menu .

One more thing:
In QFG2 you can get the "regular" debug menu (the one you get when pressing shift-shift-minus) if you switch the interpreter file (scidhuv.exe or something like that) with the one found in sierra's christmas card from 1990 - the 16 colors version.

I hope someone will make a detailed file someday that will have all the known debug modes in sierra games... I don't want this knowledge to be forgotten...
o I just found out that there is a way to enable the debug mode in Laura Bow 2:
You'll need special debug script files that somehow found their ways to the internet. They can be found at: near the bottom of the page.
Very extensive debug mode!
Lars Try this one...

In GK2, enable the debug mode by creating the classes file,
then start the game. When the "where to" dialog box appears
enter 98 in the input field.
Omer Mor Found a new one:
In Police Quest 4, if you rename the file "PATCHES\4.SCR" to something else, the debug mode is enabled, and you can choose where and when to start, and can access the debug menu by pressing the '?' key.
Since you remove a script, and not add one I guess this script only DISABLES the debug mode, so maybe a similar "disabling script" exists in other games.
Can anyone disassemble that script (it's quite short) and shed some light on this?
I can send that file to people who don't have it and wish to investigate on this.
Omer Mor.
Brian_Provinciano There's definately no disabling script in SCI1 games. Not only does the debug mode not work with my single script test games, but through disassembling of the actual SCIDHUV.EXE, I have discovered that it was completely removed.

I have found a very very early VGA interpreter that has a debug mode, but it is incompatible with all other VGA games. And also, though it's named version "X.XXX.YYY" or something, I've found other interpreters to also be named "X.XXX.YYY" which are completely different, so it can't be clearly identified. I plan on inspecting it further, but at the moment am busy with other SCI stuff.

The PQ4 off my collection CD had a level select in it as well. I think I forgot to copy all the files when I copied it to my HD. I didn't realize it at the time, but thought it was odd.

Thanks for posting the info!
Omer Mor Brian,
I think we're not fully understanding each other.
From what I've seen so far, I believe that there are 2 kinds of debuggers in SCI games:

1. The built-in debugger. This one was run when you pressed the "Shift-Shift-Minus" combination, and is a low-level debugger. This debugger was built in the interpreter file, and was removed in SCI1 games (I too have one SCI1 interpreter with debugger. I think it's from "Jones in the Fast Lane").

2. A script-debugger (I think AGI games had script-debuggers too). Some of those debuggers were activated upon writing a specific sentence (e.g. "Suck Blue Frog", QFG2). Some were activated upon putting an empty CLASSES file in the game's directory. What they have in common is that they are game-specific, and they're found in the game's script files. I believe they were removed/deactivated for some games.

The debugger I mentioned in PQ4 is a script debugger, and the interesting point is that it was deactivated using another script file: "4.SCR". If you remove that file, the debugger is active again! So if someone could disassemble that script file, we'll:
1. understand this "deactivation" mechanism more, and-
2. might find such scripts in other sierra games.

I've written this before, but it's appropriate here too:
There are some files on the net that activates the script-debugger in the Laura Bow 2. This files, when put in the game's directory enables the debugger. I think disassembling those files might be educational as well.

I am willing to send all the files that I mentioned to anyone interested. Just mail me: sitrajunk *at* .
Brian_Provinciano I understand you.

All SCI games had script debuggers, and some had internal ones. However, I have been unable to find any SCI0 games that aren't stripped of their script debugger. The SCI0 script debugger showed info on actors and such (as seen on the menubar in some of sierra's screen shots in a promotional video). It was controlled by a global variable, but since the scripts were removed, it won't work. Setting the global variable would just cause a " not found" error. I believe it was which checked this variable to call the script, though I removed the calls from the template during the cleanup.

The internal debuggers are basically about tracing opcodes, viewing/changing memory/objects.

The script debuggers are actually more useful for the game developers. They include info on aspects of the game relating to the class system.

I highly doubt any SCI0 games (excuding the SCI01 QFG2) were released with their script debuggers, just like no SCI0 interpreters have their symbols left in. I'd probably have to write one myself.

If you ever find any SCI0 games with script debuggers, or more importantly, symbols in the interpreter, please let me know which ones they are.
Omer Mor There is of course QFG1 with a script debugger - you run it with this sentence: "razzle dazzle root beer".
I'm not sure this is THE script debugger that was controlled using the global variable, so you'll need to check this one further.
About the symbols: I think I have all SCI0 games known, so give me a good and quick way to find out whether the symbols were left in the game, and I'll run a check for you. Can I use an hex editor for that?

What about the 4.SCR file from PQ4? Is there anyone willing to disassemble / decompile it? Anyone?
Omer Mor Since there seem to be no interest in decompiling the 4.SCR from PQ4 (which deactivates the debug mode), I might give it a shot myself.

Does anyone know how to do the following:
1. Extract resource from an SCI11 / SCI32 (I'm not sure which one is PQ4).
2. Disassemble scripts from SCI11 / SCI32.

Omer Mor.
HwM Uh... The Police Quest 3 debug mode is activated by setting the attribute on the file "version" read-only...
HwM Also, to be on-topic, my version of Police Quest 4 doesn't have a 4.SCR... It's the disk version, version number 1.000...
Brian_Provinciano I've just finished the 25th script of my VGA template, and have five or so left. I normally would look into disassembling it the PQ4 script, but after the 30 EGA scripts, and now 25 VGA scripts, my head is spinning, heh. I'm going to finish disassembling the last VGA scripts then move on to the SCI Studio VGA program itself. After my brain has relaxed from disassembling, I'll dwell into it.

By the way, don't worry! This topic to totally SCI related! Feel free to continue posting to this, and any more topics like it you wish. This message board is open to absolutely anything SCI!
Omer Mor Thanks Brian.
And HWM:
1. When you change the attribute of the 'version' file in PQ3, do you get other debug mode than the one you get when you delete/rename that file? (not a real debug mode - you just get to choose on which day to start the game)

2. in the CD version that file was in the PATCHES subdirectory. try removing other script files in floppy version and see if that have any effect, or - try to make an empty file named 'CLASSES'. it works in many sierra games. maybe that'll activate the debug mode in PQ4 - floppy version. I don't have that version to try.

3. do you know where I could find that version? how big is it anyway?

Omer Mor.
HwM PQ3:

Yes, indeed, but I thought you didn't get it to work, because you said "However, I didn't find any debug menu ."


There isn't a PATCHES directory at all in my version. I've tried to delete other SCR files, but nothing happend (the game would run normal). CLASSES does nothing... Pressing SHIFT-SHIFT-MIN crashes the game, instead of just displaying "Oops, you did something... etc. " (with SCI1 games). I don't have a clue how to get the version, it most likely the first release of PQ4, on floppy disks... It's 20.455k... And it's SCI32 i presume, bundled with that (at that time) very common DOS4GW extender...

Now, I wonder if anyone checked the rare SCI version of Mother Goose, since I think that one still contains a debug mode... I was checking a savegame of MG, and found strings like:

vanishingX: vanishingY:  About game ^a Help #1 Game Kids #5 Disk #7 Speed Change... ^s -- Faster + Normal = Slower - Sound Volume... ^v Sound Off #2 1 Debug Game`^g :Cast`^c :Ego`^e :Memory`^h :--! :Visual`@v :Priority`@p :Control`@c :--! :WriteEgo`^w :Set Debug`^D Cheat Teleport`@t :Room num`@r :Input`@i :Set Vanish`@y

After disassambling the scripts, I guess that SCRIPT.997 controls it, however I don't know if this is the SCI0 debug-mode you all talk about...
Omer Mor PQ4:

You can try finding the version using a HEX editor (like HEX Workshop) on the sierra.exe file. try looking around the end of the file. newer games also have the compilation time & date, so you can search for '199' which will find you the year string, and usually near it is also the version. I think the version of my PQ4-CD is 2.100.004, but i'm not home right now, so i'm not sure.


I checked out this version too, but you must tell me: do you have the AMIGA version with a PC interpreter, or do you have an authentic PC version of this game? because I've been looking for one for so long!

About the debug mode: This looks cool! I wonder how you can try to access that script. maybe you need to change the global variable Brian talked about about earlier that should put you in the debug mode. I don't know which global variable this is, but you can change those variables in the internal debug mode (using shift-shift-minus).
Brian - what is that global variable, and what value does it need?
HwM PQ4:

The version is: Jan 10 1994 16:29:18 2.000.000


I've got the original PC version... I've talked to you (i suppose), about this subject earlier, however, you never replied at one point...

And I know about this global variable, but yet not found it...
Omer Mor I must have missed your post at that time (sorry), but I just saw it...
Can you put that version on the web?
because my email is hotmail, and it won't be able to handle the whole game...
or maybe we could use ICQ / messanger?

any other rare games on that CD (or others) ?
maybe EGA version of KQ5? EGA version of Jones?
HwM I'll see if I could upload it somewhere...

And I don't know if there are other rare versions of games on that cd... The most games are just in VGA, if I remember correctly... Little sidenote: the EGA version of Jones was kinda wide-spread, if I believe...

Here's the list of the CD (only the Sierra games)

Astro Chicken (from SQ3)
Astro Chicken II (from SQ4)
The Black Cauldron
Castle of Dr. Brain
Codename: Iceman
Crazy Nick's Software Picks (all)
The Colonel's Bequest
Conquests of Camelot
Conquests of the Longbow
Eco Quest I
Eco Quest II
Freddy Pharkas Frontier Pharmacist
Gabriel Knight
Hoyle's Book of games vol. I
Hoyle's Book of games vol. II
Hoyle's Book of games vol. III
Hoyle's Classic
Island of Dr. Brain
Jones in the Fast Lane
King's Quest (+Enhanced version)
King's Quest II
King's Quest III
King's Quest IV
King's Quest V (+ CDROM version)
King's Quest VI
Laura Bow II
Leisure Suit Larry (+VGA version)
Leisure Suit Larry II
Leisure Suit Larry III
Leisure Suit Larry V
Leisure Suit Larry VI
Man Hunter New York
Man Hunter San Francisco
Mega Math (-ed: i think this is a dynamix game)
Mixed-up Fairy Tales
Mixed-up Mother Goose (+VGA CDROM version)
Oil's Well
Police Quest (+VGA version)
Police Quest II
Police Quest III
Police Quest IV
Slater & Charlie go Camping
Space Quest (+VGA version)
Space Quest II
Space Quest III
Space Quest IV
Space Quest V
Turbo Science
Twisty History
Quest for Glory / Hero's Quest (+VGA version)
Quest for Glory II
Quest for Glory III
Quest for Glory IV
Christmas Demo '90
Christmas Demo '92

So all the games released (the CD being from '94), excluding Christmas Demo '86, MG AGI, KQ4 AGI and maybe some others...
Omer Mor The games that I'm looking for are:
Hoyle Classic Card Games
Slater & Charlie

They're all SCI games, right?
Is the Mega Math and SCI game?
Brian_Provinciano I've never heard of Turbo Science, Oil's Well and Slater & Charlie go Camping. Do you have any information on these? Which generation of SCI did they use?
HwM Turbo Science is just like Mega Math, a Dynamix game with a Dynamix interpreter... But this list I posted, wasn't made by myself and contained some errors... Oil's Well is a remake of the original arcade game (by Sierra) and does use the common file system, PATCH files et al, but most likely isn't anything like SCI... Mixed-up Mothergoose SCI is ofcourse SCI0... Hoyle Classic Card Games is SCI1... And Slater & Charlie is SCI... However, I do not know what kind of SCI... When I let the game display the "Oops! You did something we weren't expecting." message, it gives version 1.cfs.08... So it most likely is SCI1... It's a edutainment game, click-and-see-what-happens... I believe some of these games were available at The Underdogs, but due to the bannings of some games, the downloads could be removed... EDIT: Megamath & Turbo Science are in fact Sierra games, but were developed by Jeff Tunnell productions.