What would be involved to port dreamcast games to naomi?

[Unessential]

The dreamcast has basically the same hardware as the naomi except for less memory right?

So I'm guessing the only thing stopping dreamcast games from running on naomi would probably be stuff like header information? or certain flags? maybe encryption? or just locking by software?

Has anybody attempted this before and were they successful? or has anybody broken down naomi/dreamcast programs and compared them?

It would be useful for me to run Super Street fighter II Turbo, and Puzzle fighter in a supergun/cab or one of those many unlicensed shmups that popped up after the dreamcast was discontinued as well. There are actually quite a few "arcade" games on the dreamcast that could potentially be backported to the naomi that would work well in a cabinet.

 

[Evan]

I would assume its most like a decent amount of stuff preventing the easy porting, as I bet many naomi games use the extra ram it has, and you would need immense knowledge to port them. Its probably more feasible to port it to the atomiswave, as from what I understand that is near identical to the dreamcast hardware wise, besides the obvious cartridge size limitation. But I have no technical experience in this regard, so what I say with a grain of salt.

 

[the Goat]

Porting Dreamcast games to NAOMI would be all but impossible without the original source code. Dreamcast games are programmed to execute from a GD-ROM. They have loading routines that execute between levels etc. to load data off the GD-ROM into memory. NAOMI games are programmed to execute directly out of memory. Even the GD-ROM NAOMI games are unaware they were stored on a GD-ROM. The entire game is loaded off the GD-ROM and stored in the DIMM board memory before the game is executed.

 

[mathieulh]

Porting Dreamcast games to NAOMI would be all but impossible without the original source code. Dreamcast games are programmed to execute from a GD-ROM. They have loading routines that execute between levels etc. to load data off the GD-ROM into memory. NAOMI games are programmed to execute directly out of memory. Even the GD-ROM NAOMI games are unaware they were stored on a GD-ROM. The entire game is loaded off the GD-ROM and stored in the DIMM board memory before the game is executed.

"Just" write a loader that hooks gdrom reads and redirect them to fetch the data from some location on the dimm board.

Something similar was done for Atomiswave converts, Atomiswave games normally run from rom rather than the dimm board and hw addresses are different.

Nobody bothered with running dreamcast games from naomi despite the fact that the naomi comes with full mapple support (you would need extra work if you want to play Dreamcast games using JVS), because, let's face it, you can just get a Dreamcast. Also some games like Sonic Adventure do not play well with the extra ram and just crash.

To be fair, it would probably be more interesting (and is likely feasible) to port Atomiswave games to the Dreamcast.

 

[ekorz]

Can Naomi 2 run DC games somehow?

with input from a dc/naomi expert, @MetalliC, and also my favorite quote of his, ever

 

[MetalliC]

Nobody bothered with running dreamcast games from naomi despite the fact that the naomi comes with full mapple support (you would need extra work if you want to play Dreamcast games using JVS), because, let's face it, you can just get a Dreamcast.

+1

To be fair, it would probably be more interesting (and is likely feasible) to port Atomiswave games to the Dreamcast.

agree, Dreamcast IMO have much larger fanbase, which will be happy to get some new games from AW

music/sound data streaming speed might be a problem, but in the rest it looks doable

 

[GeekMan1222]

If I recall I think there was a person tinkering around with trying to do this somewhere on the Internets.
Maybe it was just using the GD-Rom emu board to load Naomi games, I didnt pay much attention to be honest.

I am sure if someone tried hard enough you could probably fudge it to work with some clever patches or software hooks to spoof dependencies or other things. The real question as mentioned before, is the need to do so stronger than just hooking a Dreamcast up to a Tri-Sync and calling it a day lol.

How far is someone willing to put in a level of effort into doing it beyond just exploratory tinkering.

 

[Unessential]

hmm. this is all very interesting and insightful. considering how many games were ported from naomi to dreamcast, I wouldn't be surprised if there are "cheats" that do most of the work of mapping GD rom to DIMM automatically.

I've only ever used naomi carts and a net dimm, so it never occured to me that a naomi loaded the entire game to the dimm on boot up, but it makes sense, considering how net dims work it wouldn't be that different.

@'GeekMan1222 GD-Rom emu board to load naomi games? that's the other way around (weren't most if not all naomi games officially ported over to dreamcast?) But It could be helpful if you could track that page down. (I couldn't =( )

@mathieulh I tried hooking up a dreamcast keyboard to the maple port a couple years ago by hacking up a dreamcast extension cable and playing typing of the dead and that lupin typing game... Didn't work, also tried using a dreamcast controller too for other games.

it could have been just a bad connection, I should give it a try again sometime soon. I just assumed the JVS controls would have been tied to the maple controls somehow (maybe just hardcoded in software) and it would just work after porting. But yeah, if i need to use the maple ports, that would require a bit more work inside a cab/supergun to have a seamless setup assuming a game port is successful and is running...

 

[mathieulh]

hmm. this is all very interesting and insightful. considering how many games were ported from naomi to dreamcast, I wouldn't be surprised if there are "cheats" that do most of the work of mapping GD rom to DIMM automatically.

I've only ever used naomi carts and a net dimm, so it never occured to me that a naomi loaded the entire game to the dimm on boot up, but it makes sense, considering how net dims work it wouldn't be that different.

@'GeekMan1222 GD-Rom emu board to load naomi games? that's the other way around (weren't most if not all naomi games officially ported over to dreamcast?) But It could be helpful if you could track that page down. (I couldn't =( )

@mathieulh I tried hooking up a dreamcast keyboard to the maple port a couple years ago by hacking up a dreamcast extension cable and playing typing of the dead and that lupin typing game... Didn't work, also tried using a dreamcast controller too for other games.

it could have been just a bad connection, I should give it a try again sometime soon. I just assumed the JVS controls would have been tied to the maple controls somehow (maybe just hardcoded in software) and it would just work after porting. But yeah, if i need to use the maple ports, that would require a bit more work inside a cab/supergun to have a seamless setup assuming a game port is successful and is running...

As far as I know of, the keyboards were originally wired to the mapple connector to begin with, you probably did have a bad connection.

About the Dreamcast games, I don't think there are any cheats to speak of, I think they just build for different targets in mind with a define for each case.
The GDROM were meant to load entirely to the dimm board at boot because cabinets were designed to run for hours straight and they wanted to minimize the wear on the drive mechanism, it's not like they expected people to change games every few minutes on arcade cabinets.

It appears to me that DIMM boards (not the netdimms) were most likely originally used/intended for development and to be connected to a host development computer via SCSI (beats reflashing an expensive flashrom cart to test builds), instead of designing something entirely new, SEGA just repurposed it by flashing another firmware on those units and pairing them with the GD-ROM drive, later on the design was improved upon and units were supplied with a net daughterboard, presumably when the need for satellite games arised. Why had they not used the already existing communication board for it? I can't tell.

 

[brizzo]

It appears to me that DIMM boards (not the netdimms) were most likely originally used/intended for development and to be connected to a host development computer via SCSI (beats reflashing an expensive flashrom cart to test builds), instead of designing something entirely new, SEGA just repurposed it by flashing another firmware on those units and pairing them with the GD-ROM drive, later on the design was improved upon and units were supplied with a net daughterboard, presumably when the need for satellite games arised. Why had they not used the already existing communication board for it? I can't tell.

The naomi development kits used a standard board set paired with a development rom board (not even remotely close to technology used in netdimm) that connects to cart interface with large ram array and scsi interface connected to host PC. If you look at naomi pcb, you will notice there are components not populated -- they were populated on dev kits. I would suspect DIMM board + GDROM was a cost cutting solution compared to selling operators a new cartridge loaded with expensive flash chips.

 

[mathieulh]

It appears to me that DIMM boards (not the netdimms) were most likely originally used/intended for development and to be connected to a host development computer via SCSI (beats reflashing an expensive flashrom cart to test builds), instead of designing something entirely new, SEGA just repurposed it by flashing another firmware on those units and pairing them with the GD-ROM drive, later on the design was improved upon and units were supplied with a net daughterboard, presumably when the need for satellite games arised. Why had they not used the already existing communication board for it? I can't tell.

The naomi development kits used a standard board set paired with a development rom board (not even remotely close to technology used in netdimm) that connects to cart interface with large ram array and scsi interface connected to host PC. If you look at naomi pcb, you will notice there are components not populated -- they were populated on dev kits. I would suspect DIMM board + GDROM was a cost cutting solution compared to selling operators a new cartridge loaded with expensive flash chips.

Interesting, do you have any source/link for this? I would have loved to see a picture of the old development setup. That said what you described is pretty much a dimm board (in prototype form).

 

[AMS]

I remember the old dev kits are the same a stage kitana ones used also for Dreamcast but combined with a extension PC Card with a SCSI connector. I have to digg in my files I should have some pictures from it

 

[RealMFnG]

This is going to sound facetious and low-tech, but JAMMAizer!

Also, other things to be factored in is porting VMU support over into NAOMI hardware. There was always a team of people that would work on porting an arcade title to the Dreamcast (a director, producer, lead software engineer, QA, localization). They would work on one title at a time and knock it out quickly. And they would have access to the source code. Every DC game is going to be different. If anyone ever tinkered with it, they'd port one title at a time and as a solo effort. Perfect it, write about how it is done so that the effort could foster others to pick up the mantle. But what value is there in doing it other than to show that it can be done? It's such a narrow niche. The convention is port arcade to console. Hardly is there ever a need to go the other way around. And if there was............

.........that is why we have JAMMAizer. Also, Dreamcast isn't the only console with arcade worthy titles either. JAMMAizer and the other two options on the market (JAMMACON and SCART2ARC3.0) allows you to play all those games on a cab. Best of all, you can do that now instead of waiting for someone to figure it out.

 

[MetalliC]

Interesting, do you have any source/link for this? I would have loved to see a picture of the old development setup. That said what you described is pretty much a dimm board (in prototype form).

common older type NAOMI dev board:
https://www.mameworld.info/ubbthrea...d=news&Number=349896&page=&view=&sb=5&o=&vc=1

newer type:
http://www.citylan.it/wiki/index.php/Puyo_Puyo_Fever_(prototype_ver_0.01))

they are basically flash ROM board with SCSI controller chip and UART. not any like DIMM board.

PS: there was old rumors about "DIMM was mainly developed for dev/debug purposes", but they are clearly not true.

 

[AMS]

Cool I have one of those programm Naomi boards laying around and some test cards used on some shows with the flash and the screw down sec chips

 

[MetalliC]

Cool I have one of those programm Naomi boards laying around and some test cards used on some shows with the flash and the screw down sec chips

which games they are ? curious to see PCB photos as well

 

[AMS]

@MetalliC I have a undumped king of Route 66 and a early tech demo of f355 and crazy taxi. And that f355 Card can run on a Naomi 2 system little flaky but it will run will dig it up and make a video


here are some pics:

 

[MetalliC]

looks great!

will dig it up and make a video

please take a photos of BIOS ROM TEST screens, if possible.

 

[AMS]

Sure will do @MetalliC i remember the whole rom test bios was all kinds of numbers and letters verry strange

here you already can see the diff on startup screen of the route 66. No Sega am-2 logo s and other design of the main screen also the game has other game options and colours

 

[AMS]

@MetalliC here