technical question about ROM/RAM cartridges

[CHAZumaru °_°]

Hi to ya all, I'm new to the board and an active Saturn defender.

I have a pretty technical question to ask to SNK conversions living encyclopedias, confirmed Saturn developpers or (don't ban, wait and read ^^) emulator creators. In a nutshell, to anyone with a deep hardware basis.

The Sega Saturn has 2 (official) RAM cartridges to increase it's RAM for games such as SNK or Capcom arcade convertions...

But there are also 2 games, "The King Of Fighters'95" and "Ultraman Hikari No Kyojin Densetsu" that use a specific ROM cartridge. Let's forget about the second game and focus on KoF'95.

What I would like to know -the most accurately possible- is :

WHAT is in the ROM cartridge of the game ?

What is stocked in it ?

And why did they pick a ROM cartridge instead of a simple RAM extension (like they did afterwoods for obvious financial reasons) ?

A programmer I know (who has no experience of the Saturn) made the hypothesis that there’s a DSP inside the ROM, like the Sega Virtua Processor in Virtua Racing for Megadrive/Genesis system.

But the Yamaha SCSP DSP which serves as an link between the 68EC000 sound processor and the Audio-RAM would have been able to play that role, wouldn’t it ?

I also found out on gameFAQs a guide from John Hokanson Jr mentioning this :

“King of Fighters '95 used a special 1 Megabyte ROM cartridge that

predated the use of RAM cartridges. The ROM cartridge came packaged

with KOF '95, and was manufactured by SNK and Sega. It included all

the additional textures needed by the game in self-contained ®ead

(O)nly (M)emory chips.”

I know that textures and backgrounds are dealed by the VDP2 chip. Is the cartridge related somehow to the VDP2, giving him special access to the ROM information ? Therefore the disc information would be sent to the VDP1 and the the cart’s info to the VDP2 ? But then how come the ROM cart is only 1MB ?

I’m asking this after having searched for an answer for a whole week as this question emerged after a long forum discussion .

We can’t find any answer, please help us, we’re dying (almost).

Thx

CHAZumaru

 

[printf]

I'm no expert on SNK conversions, but I'll try to help you with this one...

WHAT is in the ROM cartridge of the game ?

As for Ultraman, I don't know. Animation frames maybe?

With KOF95, from all the info I have read in reviews, on the web and in faqs, I think it goes something like this:

- a mask programmed ROM cartridge

- with 2 megabyte of data

- holding all of the background pictures (screens)

With this kind of realistic setup, the SNK programmers would only have to load animation frames from CD, which could be compressed data. This should be kind of fast, and give a lot of memory for the animation data once it has been put into usable layout.

This is all based on unreliable information, so don't take it too serious.

I know that textures and backgrounds are dealed by the VDP2 chip. Is the cartridge related somehow to the VDP2, giving him special access to the ROM information ? Therefore the disc information would be sent to the VDP1 and the the cart’s info to the VDP2 ?

All 2D for tiles and backgrounds will be handled by VDP2, all textures (for sprites) and other objects (polygons) need to be sent to VDP1. Yes, some of the info from the cart probably goes to VDP2. VDP1 gets all of the sprite texture data, which is loaded from disc i think. In the game, you don't need to change the background in a stage, but you'll change sprite data all the time. Getting them from external ROM would be too slow, so I don't think the cart has animation frames on it.

I don't own the game, so I have no idea. Maybe my guesses have helped you a little.

 

[Curtis]

Duplicate thread - use the one in the Dev section and only post in one forum please.