I was trying to get into more of the Ram VS Rom limitation. The SuperCD card is basically 2meg of RAM. I'm thinking in a technical terms are there somethings a HuCard rom can can do that RAM can't?
First,
instant access to a wider range of memory. And the second is reusable data. A level or area can be build of assets reused from other areas, partially or completely - and not look the same. Those are the two strengths of hucard vs CD (specially format/design).
A much better way to ask my question to clear things up is this, are we saying that if NEC had said we want to send out a SFII demo to stores that consisted of just 1 Level, and just 2 characters and nothing else, no continue screen, no selection screen, simply let's say, Chun Li level and just Chun Li Character and Ryu. Nothing else. No nother screens. That that would not fit in a 2Meg HuCard?
Not bit for bit of the hucard version. Ignoring sprite frames for just for a sec, you still need game logic/code. You still need sprites sheets. You need animation tables. Etc. These are lookup tables with timings per frame, sequences of frame animation, meta-sprite object to low level object (real sprites). That can take up a nice chuck, especially for a fighting game with a lot of animation - not just the literal pixel frames themselves. Then add the actual pixel frames in. Samples take up space, so put them in ADPCM ram (whether you use ADPCM to play them or not. ADPCM access for read/write is slow, but fast enough for PSG PCM driver to read out and play). 2megs is 256k. Code+lookup tables are probably going to be 64k+ at minimum, but probably more. And BG data could remain all in vram (i.e. it's a separate read and load from CD). And assuming no chiptune music driver (CDDA instead). You have roughly 192k best case scenario and probably 128k worst case, left over for sprite frames. Split the difference and say it's 160k free for sprite frames. Dhalsim's fighting sprite frames (and projectiles) as 130k in the PCE hucard. That's more than half of the available sprite reserved CDRAM right there. Some characters have a little less and some have more space requirement. So could you do it? Yes, but it wouldn't be exactly like the hucard. There would be missing frames of animation.
And that's assuming all areas load from CD (map/stage/character select, continue/loose screen, etc). If this were SGX SCD, you could probably just get away with it. With its additional 24k of ram, plus having two VDC's you could have more room in each VDC. I.e. preload a few sprite frames stay in vram memory. But back to the PCE, so if the scenario you chose had two chars that required less than a total of 160k (or whatever is really available) of sprite frame ram - then sure. But what good is that, if you have to cripple other characters to conform to that?
A full 1/8 card size of the entire finished game 1 level, 2 characters, but without all 12 characters, 12 full levels, 2 bonus levels, all the speaking for the continue screens, start screen, settings screen, selection screens, all the unique endings for each individual character, the intro animation, etc? That was more what I was getting out, is there some thing different when using 2Meg card vs 2Meg ram from the SuperCD card?
Between a 2meg hucard(rom) vs 2meg CDRAM (ram)? No, no difference. But what you're missing is that the the SF2 game itself doesn't neatly divide each stage area into
evenly divided parts. If you forced it into such, something would have to give. And like I said previously, rom has the direct ability to reuse any asset of the entire rom for whatever purpose. It's a form of compression. And it's makes design mechanism that still gave advantages to hucards over CDRAM. And it's not like that 20meg hucard has lots of wasted space, because it doesn't. It's packed. Even the BG tiles are compressed (which, with a rom that size you'd figure there wouldn't be a need to for such relatively small screens).