Dreamcast N64 mod

[phisejr]

make an Emulator on the Dreamcast to run n64 games ? would you think thats possible or even worth it?

[skroooagh]

From what I understand (which isn't a hell of a lot, honestly) N64 emulation is entirely possible for some of the smaller-sized N64 ROMs out there. The reason this hasn't happened is that:

A) it won't be easy
B) it would take a lot of time, which most DC dev'rs don't have
C) you'd pretty much need a emulator built/optimised around whichever ROM you wanted to emulate, so it doesn't seem like it'd be worth the effort for just one ROM

That being said, if a N64 emulator was ever developed, I'm sure a common source could be used to let individuals create optimisations for their favourite roms. Personally, I'd love to see some of the classic games like Mario Kart/64 on DC, but I can accept that it may never happen.

[Maturion]

I think it could happen. Just look at Bleem. GPF has made a "proof-of-concept" N64 emulator by the way.

[|darc|]

Because of the Dreamcast's lack of RAM, it won't happen.

[Ex-Cyber]

I'm pretty sure that the RAM issue is negotiable to some degree. The CPU still seems to be on the slow side for emulating the N64 CPU, though. In any case, a playable emulator would take a lot of dedicated coding effort; it's not just a case of porting some existing one.

[|darc|]

I'm pretty sure that the RAM issue is negotiable to some degree. The CPU still seems to be on the slow side for emulating the N64 CPU, though. In any case, a playable emulator would take a lot of dedicated coding effort; it's not just a case of porting some existing one.

Well, you probably have more experience with this sort of thing than I do, but I don't think there's any realistic way to handle a ROM other than to load it into RAM. As I'm sure you're aware, there are plenty of games that are much larger than the Dreamcast's total RAM, even without worrying about the N64's RAM and the memory needed for the emulator to do its thing. So while it's very likely possible to create an Automobili Lamborghini emulator and quite possible to create a Super Mario 64 emulator, there are going to be games that are impossible no matter what.

I would say that CPU-wise, it's possible, perhaps just because Rand was considering doing one before he decided to do bleemcast (this would also require a hardware attachment to the G2 bus).

[Ex-Cyber]

Well, you probably have more experience with this sort of thing than I do, but I don't think there's any realistic way to handle a ROM other than to load it into RAM.

Well, I'm basing my opinion on a few key facts:

1) N64's cart interface runs much slower than the rest of the system (which, incidentally, is a big part of why it has so much RAM despite being cart-based)
2) ROM data doesn't need to be modified, so it doesn't necessarily need to be kept in RAM
3) Dreamcast has an MMU

The idea is to cache parts of the ROM in RAM as needed. The entire ROM would be mapped, but it would be paged in when an uncached piece is accessed. As to how games actually behave, it's still mostly speculative, but I would expect that most N64 games don't do very frequent cart access during gameplay. There would surely be some noticeable pausing/stuttering in some situations; the main question is how frequent it would be.

[Ex-Cyber]

(bleh, double-post)

[Christuserloeser]

The idea is to cache parts of the ROM in RAM as needed. The entire ROM would be mapped, but it would be paged in when an uncached piece is accessed. As to how games actually behave, it's still mostly speculative, but I would expect that most N64 games don't do very frequent cart access during gameplay. There would surely be some noticeable pausing/stuttering in some situations; the main question is how frequent it would be.

AES4All (Neo4All/AES) is using the MMU like you described. Works good for games well above the Dreamcast's RAM but starting at about 30 MBytes or something the loading really gets noticable. Exceptions are certain games like Shock Troopers where there's no noticable loading despite the game being 60 MBytes or whatever in size.

I would say that CPU-wise, it's possible, perhaps just because Rand was considering doing one before he decided to do bleemcast (this would also require a hardware attachment to the G2 bus).

Yup, found this post of Rand a while back - especially the last bit I found interesting:

Yes, we were looking into an adapter for the N64 cartridges -- mostly to avoid legal issues with disc images and piracy.

There were two basic concepts -- a serial-based one for games that could fit into RAM and a full G2 port adapter that sat between the DC and the modem (or BB).

The smaller carts wouldn't have been a problem, and it would have been an issue of whether or not the cost would support the ability to run the additional, larger ones.

Effectively, the smaller carts are "preloaded" at boot, and for a very small number of titles, we could patch the game code to allow 'intermission' type loading if the game was "close" to fitting but was a high profile title.

The cost to develop a full G2 device was high, but solved lots of other ancillary problems (mostly timing- and transfer- related).

The game would run through software emulation -- not a huge leap, considering the processors are VERY similar.