Qbix wrote:

Well finster made a patch that will run the game. I don't know if the patch works with 0.57. But I think it would.
If somebody tests it.
There is no objection of putting the patch here as well.

Is that a Bio Menace patch or a DosBox patch?

Finster DOSBox Author […]
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Finster
DOSBox Author

Joined: 26 Oct 2002
Posts: 48
Location: Germany

Posted: Thu Feb 20, 2003 8:19 pm Post subject:
hell, those games are buggy... they do some weird things with the interrupt table (comparing things that dont make any sense). I have attached a small patch which has to be started in dosbox before one of those games are executed. it's a simple fix writing the value 0000 at the memory address 0000:0006. Works with all three bio menaces. stupid games...

Originally posted by Snover Well, um, er, if DOSBox is supposed to emulate DOS then it should work even if the program is broken,

That's the consequence of programming an emulator that only emulates what's needed to run DOS games and not a "complete" emulator.

Nicht Sehr Gut wrote:

That's the consequence of programming an emulator that only emulates what's needed to run DOS games and not a "complete" emulator.

You would be supprised how complete dosbox has become 😀
Many games use undocumented side-effects and do weird stuff.
Especially the graphics department(VGA BIOS) is a good example of this.

But you are right offcourse. The only reason the interrupt handlers are located at an other location is that we supply the features instead of bitwise emulating/copying them.

Originally posted by Qbix But you are right of course. The only reason the interrupt handlers are located at an other location is that we supply the features instead of bitwise emulating/copying them.

This is also why 286/386 action games run properly on DosBox, but are useless on Bochs.

Uh, is the reason that happens because of the massive amount of computing power needed to emulate stuff with Bochs?

Originally posted by Snover Uh, is the reason that happens because of the massive amount of computing power needed to emulate stuff with Bochs?

Well, it's related. The reason it needs all that extra computing power is because it needs to emulate every single aspect of the PC.

It doesn't help that their VGA displays are extremely inefficient. Reminds me of when I was using the Amiga's "planar" graphics to emulate a PC with Windows 3.1 (which would normally use "chunky" graphics processing).

Even 8086 action games will be poor performers until their VGA is optimized.

Please define planar and chunky. Thanks. 😁

Originally posted by Snover Please define planar and chunky.

*grumble* Can't remember al the tech info, so I'll have to kind of paraphrase.

The number of colors you have on-screen is dependent upon the number of bitplanes in the computer's display.

1 Bitplane gives you 2 colors
2 Bitplanes gives you 4 colors
3 Bitplanes gives you 8 colors
4 Bitplanes gives you 16 colors
5 Bitplanes gives you 32 colors
etc...

Planar graphics render every bitplane separately.
Chunky graphics renders all bitplanes together.

Planar graphics excelled at at graphic manipulation. It allowed for easy, smooth scrolling (this is why scrolling was easy on the Amiga and hard on the PC) and especially handy for parallax scrolling. Planar graphics chips allowed you to render each "plane" of the background independently.

Chunky graphics chips had no hardware support for these kinds of things. That's why if you dig up old ads for some action games for the PC in the late 80's/early 90's and it featured smooth-scrolling, the ads would make a point of telling you about it. It was a major achievement of the programmer. It's why Jeff 'The Yak' Minter hated the idea of programming the PC for so long (IIRC, when VGA came out, he said it was almost worthless).

It did have one (very big) thing going for it, however, SPEED.

Attempting to run a game like DOOM on an Amiga was extremely difficult due to the (at-the-time) huge number of colors needed simultaneously and the need to update the entire screen with all those colors constantly. Chunky graphics chips did that easily.

Since then, modern graphics cards contain most of the advantages of both without the weaknesses of either. I still miss things like grabbing the screen and sliding it down to see what screens were behind it.