Dungeon Master for Apple IIGS 2.0 and 2.1 differences

[ChristopheF]

the IIGS version that did NOT work with the ROM 3 Apple IIGS, a later version DID

Can you elaborate? What were the issues with ROM03? Game not starting, freezing ? Do you know which version of the game?
I have tested Dungeon Master version 2.0 and 2.1 (both English, available for download here: http://dmweb.free.fr/?q=node/626) in the GSport Apple IIGS emulator with both ROM01 and ROM03, and both games run fine with both ROMs. However I've never played the game on a real Apple IIGS. Maybe the emulator behaves differently than the original hardware?

There are very few differences between 2.0 and 2.1 (based on my ReDMCSB source code):
- Obviously, the version number itself, as shown in dialog boxes and also used in the version sensor (not used anywhere in the original dungeon)
- Minor changes (looks like small optimizations in 2.1) in 3 graphic related assembly routines
- Version 2.0 reads mouse position directly in memory / 2.1 calls OS function ReadMouse
- Amount of memory not allocated by the game (left to the system) reduced to 16K in version 2.1 instead of 64K in version 2.0

[slickrcbd]

I'd have to get my IIGS out of mothballs to test.
What I recall was that if you tried to play the "adult" dungeon with my copy of Dungeon Master on a ROM 3 IIGS, the game would crash, IIRC with a "Fatal System error" and the sliding Apple, but I'm unsure. If however you held down the <OPTION> key to play the "Kid's Dungeon" it would work.
No such problems existed on my ROM 1 IIGS.

However another person who had played DM at my house purchased it a year later and it ran just fine on his ROM 3 IIGS.
It was a third person with a ROM 3 that we discovered this issue with, by me bringing the game disk over to his house so he could try it. I had him go through the "Kid's Dungeon" to get familiar with the game and it worked fine, then it crashed when he tried to play the real game.I was panicked, I thought my disk got damaged in transit despite using protective disk cases and since it was copy protected, it was my original and DM was my favorite game and I would be SOL.
Then I got home and everything worked fine. Experimenting with my other friend's ROM 3 we discovered that my version did NOT like the ROM 3 and would crash when you clicked on "Enter", but strangely enough would let you hold down <OPTION> to enter the "Kid's Dungeon", which I thought was an Easter Egg as I was also apparently missing the small card that talked about it.
I'm sorry I can't be more detailed, this was 30 years ago. All these events happened around 1990 or so. I think I had DM in 1989 and the other friend got it in 1990, but I could be off by a year and it was 1990 for me and 1991 for him. I don't remember. I should point out that I was in junior high back then as was everybody mentioned here except the parents.

[ChristopheF]

Thank you for all these details. Your memory is still very good after 30 years (probably the trauma of thinking your copy of the game was broken!).
Your description of the issue allowed me to reproduce the issue: in my earlier tests, the emulator was configured with 8MB of expansion memory, and in this case there is no issue. However, with ROM03 and no expansion memory at all, I can exactly reproduce the issue you described: version 2.0 (early 1989) can load the kid dungeon but fails to load the main dungeon. Version 2.1 (late 1989) fixed this issue (the memory allocation change I mentioned).
I have added that piece of information on http://dmweb.free.fr/?q=node/626

[slickrcbd]

I recall that the ROM 3 had slightly less than 1.25mb of RAM compared to a fully expanded Memory Expansion Card in a ROM 1 (the ROM 1 came with 256K built in and a 256K Memory Expansion Card, that could be expanded to 512K (768 total) or 1024K (1280K total).
I don't recall exactly what it was, it was probably 1216K or 1,152K due to the way memory worked on the platform due to the nature of the 65C816 processor and how clunky the 24-bit addressing was to accommodate backwards compatibility with 8-bit code that used 16-bit addressing.

[Gambit37]

This was quite a deviation from the original conversation

[ChristopheF]

You're quite right Gambit so I've split the topic.

[slickrcbd]

I'm afraid I never noticed any differences besides the newer version of the game running just fine on the ROM 3, while the original version crashed.
Then again, I did not play DM that much on a ROM 3. I've never beaten the game on a ROM 3 or gotten that far.
It's not like DM is a good game for two players.

Honestly, I just figured the updated version was a bug fix release to let it run on the ROM 3, as I never saw a change log or anything like that.

[ChristopheF]

You are right, there are no differences apart from the few I have listed in the first post of this topic (the list is exhaustive).
So it really looks like it was a bug fix release for ROM03 computers.
I wonder if the change about the mouse was made to fix another issue in some configurations or if it was made only to conform with the best practice of using an official API rather than reading data at hardcoded memory addresses.