Genesis limitations for arcade ports

racketboy

Established Member
I was just thinking, what were the main things holding the Genesis back from having better arcade ports of games like Street Fighter 2, Samurai Shodown etc.

Do larger sprites take up too much memory. Stuff take up too much cartridge space or what?

I'm just curious
 
I'm not familiar with the Genesis or arcade version of either of those games, but it could be a number of things. VRAM capacity is one issue. If the sprites are really big, you might not be able to DMA in the new ones fast enough to squeeze in during VBlank. Also sprites larger than 32x32 need to be rendered using multiple hardware sprites so the sprite limit could come into play (though I doubt this would be the case for a fighting game).
 

Des-ROW

Established Member
The sprite limitation would be the reason why the character Earthquake didn't make it to the MegaDrive release of Samurai Spirits.

Other things that the MVS hardware has over the MegaDrive is that it can display 4096 different colors on-screen (from a 65536 color palette), can display up to 380 16x512 sprites, and that it performs zooming by hardware.
 

ExCyber

Staff member
The main thing is ROM size. Bigger carts cost more money, and presumably it would eventually get to where you'd have to spend twice as much money on ROM to make the game subjectively look, say, 20% better. This is ignoring the bigger business aspect of having to invest in an entire cart run. I strongly suspect that most VRAM issues could be mitigated with game-specific allocation techniques.

Also sprites larger than 32x32 need to be rendered using multiple hardware sprites so the sprite limit could come into play (though I doubt this would be the case for a fighting game).

Well, Earthquake is rather wide, but the VDP's 16-sprite line capacity should be more than enough to render two guys as wide as the screen. It's more likely to be a problem for a horizontal shooter (or maybe a bullet-heavy vertical one like Varth).
 
But in a shooter the massive boss doesn't contains dozens of full animation frames, only a few small animated parts. Actually, in many shooters, when the boss if REALLY big, the bulk of the boss that has no animation is done using background tiles.

So, I guess the problem with fighting games wasn't that the character sprites were big. It was because they were big AND there are lots of different frames that need to be swapped quickly.

In the Genesis/Sega CD version of Samurai Shodown, they decided to take out Earthquake, that would surely hog the system, while in the SNES version all characters became lemmings to allow Earthquake to be in.
 

ExCyber

Staff member
But in a shooter the massive boss doesn't contains dozens of full animation frames, only a few small animated parts. Actually, in many shooters, when the boss if REALLY big, the bulk of the boss that has no animation is done using background tiles.

I was talking about the problem of having lots of bullets flying around onscreen going over the VDP sprite limit. You can only have 16 (or 20 I think if it's in 40-cell mode) sprites sharing the same scanline before the VDP stops drawing them (probably memory access reasons).
 

racketboy

Established Member
Originally posted by ExCyber@Oct 24, 2003 @ 02:27 PM

But in a shooter the massive boss doesn't contains dozens of full animation frames, only a few small animated parts. Actually, in many shooters, when the boss if REALLY big, the bulk of the boss that has no animation is done using background tiles.

I was talking about the problem of having lots of bullets flying around onscreen going over the VDP sprite limit. You can only have 16 (or 20 I think if it's in 40-cell mode) sprites sharing the same scanline before the VDP stops drawing them (probably memory access reasons).

well obviously the DC doesn't have that problem -- Mars Matrix -- AGHHHh!!!!
 
Originally posted by ExCyber@Oct 24, 2003 @ 02:27 PM

But in a shooter the massive boss doesn't contains dozens of full animation frames, only a few small animated parts. Actually, in many shooters, when the boss if REALLY big, the bulk of the boss that has no animation is done using background tiles.

I was talking about the problem of having lots of bullets flying around onscreen going over the VDP sprite limit. You can only have 16 (or 20 I think if it's in 40-cell mode) sprites sharing the same scanline before the VDP stops drawing them (probably memory access reasons).

It stops because the VDP is only fast enough to render that many sprites per line. Unlike on modern systems where the graphics are rendered to a framebuffer and then displayed, the old 2D consoles rendered everything more or less in real time. When you're running in 40 cell mode the VDP has a higher clock so it can render more sprites. And it doesn't not render the sprite completely, it just doesn't get rendered on that line. The only time a sprite wouldn't be rendered in its entirely is if the overall sprite max (which is 80 in 40 cell mode) is reached or if the per-line limit was reached on every line that the sprite was displayed on.
 

Alexvrb

Established Member
Originally posted by M3d10n@Oct 24, 2003 @ 11:48 AM

In the Genesis/Sega CD version of Samurai Shodown, they decided to take out Earthquake, that would surely hog the system, while in the SNES version all characters became lemmings to allow Earthquake to be in.

What's wrong with pitting lemmings against each other in a fight to the death??
 
I would say it was completely cartridge size limitations... they managed to get Big Bear in the Genesis conversion of Fatal Fury 2, and he was pretty big. I doubt that 2 large characters, even if they were composed of 8x8 tiles, would be in excess of the sprites per scanline limit, as this (going by ExCyber's figures) would be 128 pixels wide (per scanline) on a 320x224 screen, and 160 on a 256x224 screen. I am also lead to understand that you can get more sprites per scanline if you update the screen a certain way, but I'm not at all sure about that or the details of it... it was supposedly a trick that Eternal Champions used for more sprites and an expanded color palette. I guess it worked by drawing the screen once and then redrawing it again with a different color palette.

That being said the SNES version of Samurai Showdown was a funny joke. I like the Genesis version okay but I do miss the sprite scaling effect.
 
You can increase the number of sprites per frame with raster effects (You have 2 sprite lists in RAM and you change a VDP register so it switches between the two part way through the raster), but you can't overcome the per line limitation. Eternal Champions changed the color pallete mid-raster to get more colors on the screen.
 

Des-ROW

Established Member
Originally posted by RadSil@Oct 25, 2003 @ 10:08 AM

I would say it was completely cartridge size limitations...

Hmmm... I would not know... especially considering that even the games ported from MVS to Sega Dreamcast have smaller character sprites, take for example, King of Fighters 98/99/00/01/02 or Gekka no Kenshi 2.
 

Alexvrb

Established Member
Originally posted by Mask of Destiny@Oct 25, 2003 @ 03:11 PM

You can increase the number of sprites per frame with raster effects (You have 2 sprite lists in RAM and you change a VDP register so it switches between the two part way through the raster), but you can't overcome the per line limitation. Eternal Champions changed the color pallete mid-raster to get more colors on the screen.

I know the SCD version of Eternal Champions used HAM to get ~256 colors.
 
Originally posted by Alexvrb+Oct 26, 2003 @ 02:42 AM--><div class='quotetop'>QUOTE(Alexvrb @ Oct 26, 2003 @ 02:42 AM)</div><div class='quotemain'> <!--QuoteBegin-Mask of Destiny@Oct 25, 2003 @ 03:11 PM

You can increase the number of sprites per frame with raster effects (You have 2 sprite lists in RAM and you change a VDP register so it switches between the two part way through the raster), but you can't overcome the per line limitation. Eternal Champions changed the color pallete mid-raster to get more colors on the screen.

I know the SCD version of Eternal Champions used HAM to get ~256 colors. [/b][/quote]

There is no such thing as HAM on the Genesis. HAM is a video mode exclusive to the Amiga. All Eternal Champions does is swap out pallete during HBlank.
 

it290

Established Member
Really? I know the Genesis doesn't have HAM proper, and I know Eternal Champions doesn't use it, but I could swear I've seen a similar mode used for still pictures. Although I suppose if it did have it they could have made all those Sega CD FMV's look a lot better. Obviously due to the way HAM works it would be useless for actual in-game graphics.

Also, I think it might have been possible to include Earthquake in the Genesis verison of SS (although they might have needed a larger ROM which would have driven up production costs)- perhaps they just decided not to put him in because the character would be too big to play with/against without being able to zoom out.
 
HAM is this strange mode on the Amiga that gives you more bit-depth in one of the channels (red green or blue) by modifying it with the adjacent pixel or something screwy like that. There is no way to replicate this behavior on the Genesis.

However, both machines share a different technique to produce more colors onscreen which involves changing the pallete between scanlines. The Amiga is a little better at this since, the copper can take care of it whereas in the Genesis the 68K has to do it.
 

it290

Established Member
Right. So the technique in Eternal Champions is basically the same as that used in the Amiga game 'Lionheart'?
 
Originally posted by Alexvrb@Oct 26, 2003 @ 06:56 PM

Who says Hold and Modify cannot be done in software?

Do a google for eternal champions CD 256

I can assure you that HAM can't be done in software. There's a lot of confusion about it because there are 2 ways to get more colors onscreen on the Amiga, but only one of them has a name. One of them, HAM, is a feature of the Amiga hardware, the other one which I described above can be performed in software and can also be done on the Genesis. Since most people don't know the difference between the two, they started calling the technique to get more colors on the Genesis, HAM, because they knew the technique could also be done on the Amiga and there was a technique to get more colors called HAM on the Amiga.

Eternal Champions CD changes the pallete during HBlank, despite what some websites may say.
 
So, if the palette was changed during hblank, then only one part of the screen (or certain numbers of scanlines) could have different colors? That is, from a certain scanline on during drawing, the colors must be completely different?
 
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