#133 Incompatibility of the Warp (normal and aggressive) in Amiga emulation of Denise

[Anonymous]

I've noticed something rather strange, that I can't quite explain to myself and it's with the new Amiga game called "Tiny Pixel Adventure."
https://hoogames2017.itch.io/tiny-pixel-adventure

I started the game in latest Denise nightly, with Kickstart 1.3, 512kb chipram + 512kb slowram, OCS chipset and with only one drive (DF0). It ended, with the game-menu appearing and then, when the first level was supposed to start, only graphical garbage appearing on the screen. I used the aggressive WARP for loading and the floppy-speed of the Amiga emulation was set to 1 (normal speed).

Then I thought to myself, "Sad, seems like this nice new game need more memory than my real Amiga-500 machine has," and I tried it in Denise with 1MB of chipram and 512kb slowram and then the game ran normally with Kick1.3 and OCS. So it seemed clear to me in this moment, that this game apparently needs more than 512kB of chipram.

Then I contacted the game's programmer and asked him, if there's a chance, to make this nice game workable with 512kb chipram + 512kb slowram too and he answered, that this should actually be possible. Sadly I don't currently have a working real Amiga500 available in the moment, to test it there, so I loaded the game in WinUAE (version 5.2.0), with the same configuration as mentioned above and there it suddenly ran perfectly normally, even with 512kb chipram (and Kick1.3, only one drive and OCS).

I really wondered about that and asked myself, how it could be, that with the same configuration, the game produced graphical-garbage in Denise and I had the idea, that i could try to load the game without WARP in Denise and see what will happen. First i turned off the aggressive WARP and tried it with the normal WARP, but this changed nothing and still there were graphic-garbage, when only 512kb chipram was used. But then i tried it completely without WARP in Denise, and then it suddenly worked normally without garbage, even with only 512kb chipram (same behaviour than WinUAE then). In WinUAE, on the other side, the WARP has no influence at all, it works with and without the WARP, but in Denise, the WARP has to be turned off, it seems. So, here's the situation:

WinUAE (v5.2.0):

• the game runs, with or without WARP, perfectly fine with 512kb Chip RAM + 512kb Fast RAM, Kickstart 1.3, one drive and OCS. This means, the game would also work normally on all normal A500 Amigas, that have a A501 RAM-expansion (alot users have this, cause this was the standardsetting back then)

Denise (latest nightly):

• the game runs, as long as no WARP (whether normal or aggressive) is used, also with 512kb chipram + 512kb fastram, Kickstart 1.3, one drive and OCS.

• when WARP is used in Denise (no matter if normal or aggressive WARP), the game only produces graphical garbage. but when the user set 1MB chipram, then it works without garbage, even when a WARP is used in Denise (rest of the config again is Kickstart 1.3, OCS chipset and only one drive).

Sadly I can't say at the moment, how a real Amiga500 behaves here (perhaps you have a working one handy and could test it against), but isn't it strange, that here in Denise, the activation ot the WARP, seems to lead to the situation, that apparently more chipram is required then, to run this game without graphical glitches? I never had something like this, in all the years, in which I emulate Amiga-software. Have you ever had a case like this, Piciji and can you reproduce it, on your PC? I just thought, I'd report this thing, maybe it's some kind of bug or something, and if not, then it wasn't so bad, to have reported such a special case, because this is a rare behaviour. How can an emulator-WARP can have influence on the memory, a user needs, to emulate an Amiga-game without problems? Maybe you have an idea?

[PiCiJi]

the game runs, as long as no WARP (whether normal or aggressive) is used, also with 512kb chipram + 512kb fastram, Kickstart 1.3, one drive and OCS.

when WARP is used in Denise (no matter if normal or aggressive WARP), the game only produces graphical garbage. but when the user set 1MB chipram, then it works without garbage, even when a WARP is used in Denise (rest of the config again is Kickstart 1.3, OCS chipset and only one drive).

For me, the situation is exactly the opposite. With 1 MB of chip RAM (A600 or A500+) and no other RAM, I get the problem described. 0.5 chip + 0.5 slow (A500) works for me with Warp. (in most cases)
The same problem occurs in WinUAE with 1 MB of chip RAM. Unfortunately, I don't have an A600 or A500+ (which have 1 MB of chip RAM) to use. My two Amigas are A500 OCS and ECS, each with 0.5 of chip RAM and 0.5 of slow RAM.
There seems to be a bug in the game. If you wait too long on the title screen, which can easily happen with Warp, the problem occurs. (1 mb chip and no other RAM) Denise's Warp is faster than WinUAE's. That's probably why you didn't notice the problem in WinUAE. If you can confirm this, perhaps the developer should test the game with an A600, which uses a 1 MB chip and no other RAM.
note: I don't have tested combinations with fast RAM.

edit: The problem is mentioned in the comments on the game's homepage on an A600.

[Anonymous]

Hello. First of all, I have not tried it with Amiga-modell A500+/A600. I had tried it with ECS A500 together with 1MB Chipram + 512kb Slowram and then the behaviour is exactly like I had written, here on my PC (tried it again today). But you are right, when I try it without any Slowram, which I did the first time today, then the game constantly crashes. But this crash is not, what i meant, when i wrote about this graphic-garbage problem of the game, because without Slowram, the game goes into a blackscreen and that's it.

Then i tried out, what you had written (wait longer on the game's title screen) and for this, I used no WARP in Denise (together with 512kb Chipram + 512kb Slowram and Kick1.3 with Modell A500, exactly like I did it some days before) and then indeed, the game brings this graphic-garbage and then crashes, also when no WARP is used. So this waiting-time really seems to be the problem here. Together with a WARP it crashes more often then, because time goes by, alot faster in the title-screen when game runs faster. :-) And also in WinUAE, I could recreate this behaviour of the game, when i wait longer in the title-screen, so this seems to be no problem of the emulators, but indeed a problem of the game, or better lets say, one of the two problems of this game.

Problem (1) of this game - if the user waits a bit in the title-screen of the game (for example two or three minutes or more) and only then starts the game, it brings graphic-garbage and crashes (at least in the most times, I also had it one time, that it nevertheless worked then, but in most times, it crashes then). And of course, together with an activated WARP of an emulator (Denise or WinUAE), these two or three minutes waiting-time, is reached alot faster, depending on how fast the PC of the user is.

Problem (2) of this game - if the user has no Slowram in his Amiga-machine (like for example a standard Amiga-600 has it (1MB Chipram and 0kb Slowram)), then the game crashes all the time. Not with this mentioned graphic-garbage screen, but with a black screen, before the first level should begin. Game definitely needs Slowram, for whatever reason?

I hope a V1.1 of "Tiny Pixel Adventure" comes out, that has these two problems solved. Overall, it's a good new game, especially considering, it was made with something like a construction-kit engine. For that, it's really nice, because most games like that, aren't really good in my experience, but this one is well done.

So, what matters to Denise here is, that it's not an emulator bug, but a problem of the game, that also happens in WinUAE for example. You'd never guess, that waiting a bit longer on the title screen would cause such a problem, but of course in hindsight, it makes sense now, because it mainly occurred with WARP enabled and time passes faster on the title-screen, with this function activated. lol , crazy thing.