Replace GD-ROM with Flash Card?

[angelwolf71885]

Well this mod we could use cf card like the Sega Naomi i think they used a new bios i think i am unsure but would be a cool mod.

well the NAOMI was deigned to load from flash carts to begin with those big card things that plug into the scsi ports
to even use the GD drive for the naomi/2 you need a most up to date bios the origanial naomi required revision H not sure what 2 required

ive been wondering the last few days might it be possible to mod the naomi bios to accept dreamcast games and use the designed for naomi ROM cart
or even see what the naomi dose to load from flash cart and replicate it into the dreamcast

[bart_simpson]

Well it should run dreamcast games as its like the same just the arcade version.
Good luck

[l_oliveira]

ive been wondering the last few days might it be possible to mod the naomi bios to accept dreamcast games and use the designed for naomi ROM cart
or even see what the naomi dose to load from flash cart and replicate it into the dreamcast

Perhaps an hacked/modded Dreamcast BIOS for working with NAOMI would do that job ?

[angelwolf71885]

Perhaps an hacked/modded Dreamcast BIOS for working with NAOMI would do that job ?

it might the naomi and dreamcast are basically the same just with different bios's and the naomi has double ram
much like the dev kit bios was able to be modified for the dreamcast

[Bad_Ad84]

The link83 bios isn't the dev bios that's modded to run on the dreamcast. Its the dreamcast bios that has had the dev intro added to it.

[runkthepunk]

it might the naomi and dreamcast are basically the same just with different bios's and the naomi has double ram
much like the dev kit bios was able to be modified for the dreamcast

The link83 bios isn't the dev bios that's modded to run on the dreamcast. Its the dreamcast bios that has had the dev intro added to it.

So just want to clarify if the NAOMI bios was flashed to the Dreamcast and someone skilled with replacing chips (like Bad_Ad84) fitted the correct amount of ram to the DC board, GD ROM NAOMI at home is possible? It seem like it would be more complicated than that otherwise wouldn't it have already been done.

[angelwolf71885]

The link83 bios isn't the dev bios that's modded to run on the dreamcast. Its the dreamcast bios that has had the dev intro added to it.

i thought it was the dev bios modified to run millCD and retail thanks for clarification

So just want to clarify if the NAOMI bios was flashed to the Dreamcast and someone skilled with replacing chips (like Bad_Ad84) fitted the correct amount of ram to the DC board, GD ROM NAOMI at home is possible? It seem like it would be more complicated than that otherwise wouldn't it have already been done.

i dont think it would work with naomi bios in dreamcast because the games are coded different

but what ive been wondering might be possible is running the dreamcast bios on a naomi might be possible
but getting the rom cart to work would be a challenge

also why the naomi games wouldn't work on dreamcast is they are designed to be run from the rom cart
witch has 3 scusi or G! port or what ever the hell the connection is called that connect the GD drive to the dreamcast
the naomi rom cart has 3 of those ports

[splith]

So just want to clarify if the NAOMI bios was flashed to the Dreamcast and someone skilled with replacing chips (like Bad_Ad84) fitted the correct amount of ram to the DC board, GD ROM NAOMI at home is possible? It seem like it would be more complicated than that otherwise wouldn't it have already been done.

No, it wouldn't work at all. There is a lot more to a NAOMI than just a 'modded dreamcast'. NAOMI's have ASICs and other things that the dreamcast doesn't have.

[sonicdude10]

I've been thinking on this for a while. While I have no technical expertise in stuff like this I do have a basic understanding.I've come to this conclusion. With Dreamshell 4.0 being out and SUPPOSEDLY having support for HDD, my best bet for this would be an FPGA like the Everdrive flash carts. If the coding for it was done right, it could even "fool" the Dreamcast security check and boot into a custom loader screen. The FPGA mimics the GD ROM drive and interfaces to 1 or more SATA ports. SATA II should be plenty fast for this. To take this further, make it so that any SATA storage device is supported including DVD drives and other what not. Granted you won't get to play DVD movies but custom ROMS that exceed the 1.2 GB limit of GD disks would be able to run. Once I start learning coding in college I may take a look at the communication protocols in the Dreamcast and see if I can make an adapter to take the GD ROM port and convert to SATA. If I ever do this and were to get enough interest, other things could be possible with the FPGA. USB device support. Homebrew Ethernet adapter. Perhaps even an MPEG adapter that fits in the expansion slot for true DVD video support. All ambitious ideas for a dead console. The life of a "stone age gamer" person. Go ahead and shoot my dream down. Most likely won't ever happen. If people really did care as much as they say they do, something would have happened already. It's been 13 to 14 years since this console came out. The Xbox 360 has been around for like 6 to 7 years and there is already a DVD bypass device for it to boot disk ROMS from the HDD. How's that fair? Blame it on consumer interest? Meh. Gotta stop before I explode from anger at this.

[Calpis]

All excellent ideas that are extremely valuable to this discussion, I highly suggest you blog your technology musings so I can, uh, read, them there.

[cybdyn]

not only you thinking of this idea - sd/hdd cd-dvd drive to DreamCast. there is nothing impossible, all sega dreamcast HW is based on old style
technology of 1998-2000 years.

theoretycally its possible make SATA (1/2) controller in FPGA, but i think its complex, you need fast chip and actually SATA protocol is not just seriallized ATA protocol in real. so better try use converter IDE->SATA first.

i think there are two way of making device of GD-EMU:
1 - HW gd-emu board for g1 bus like original
2 - SW based emu - it works like SD-mod, that is based on changing the syscalls (or bioscall) that work as driver for gd-rom, so we can rewrite code for any device we made , and remap syscall with ours. so in this way you can make your own device, using G1 or G2 bus.

i work on this idea, when i got free time. i plan my test-board will work similar to PSIO project that is for PS1.

as for now i stuck on installing KOS compilers. i can compile only asm files. but then i start assemble test board to DC and launch IPL code.

[cybdyn]

sonicdude10 - so what is your plan or it was just a dream?)

[sonicdude10]

sonicdude10 - so what is your plan or it was just a dream?)

not sure at this point. I need to get into my collage coarse first before I decide on this. It would make for a good term assignment in the programming area. So this is currently a dream that could turn into a plan. As for converting the G buses to IDE, that would most likely be the best bet. From what I can remember the communication signals are somewhat like the older 50 pin SCSI format yet far different at the same time. The FPGA used for converting the G1 bus to IDE would need like 100 pins in it to work and stuff like that costs money not to mention the custom PCB needed. The idea for the homebrewed ethernet adapter and MPEG will be harder. The ethernet port will be simple enough since it has been made by Sega. The difficult part will be the hardware MPEG decoder in the FPGA on the G2 bus. Not only will there need to be the code for the FPGA but also code for it to run in tandem with the CPU and a custom BIOS will most likely be needed. Perhaps it can be made to load through Dreamshell. All of these things I want to try and most likely will but I can't promise anything now. Gotta learn coding, Dreamcast communication protocols, FPGA coding, PCB designing, and other little things before i can even think about doing this. If I succeed on the IDE adapter I know there will be a market for it. Same for the ethernet adapter since it would most likely be cheaper than the real thing. The hardware MPEG decoder is the wild card here. For it to work the user would need the IDE adapter to hook up a hard drive with DVD movies ripped on it or an IDE DVD drive. You tell me people. Would it be worth while to you Dreamcast fanatics to have it play DVD movies or would having a storage medium option in place of the GD-ROM be enough? How about the network adapter? Am I wasting my precious brain on this or are there some people interested for this sort of stuff? Seems to me that the original people working on the GD to IDE boards either gave up or went into hiding. Someone has to do something to keep this ancient marvel of hardware alive. I may be a newb here but I want to do my part and also make a buck or two while at it. I can't promise anything but to try when the proper time comes for me to do so. That time being when I learn enough coding to understand the language scripts.

[cybdyn]

g1-bus is very similar to ide bus with addional sound channel through AICA for playing CDDA music on background.



making of MPEG decoder in FPGA is hard and can be worthless thing. as i know DC can play AVI movies on software level. cause SH4 is pretty fast (200Mhz).

[Hamster]

I have two GD-ROM Drives that use the drop in assemble from the Dreamcast, the Later model GD-Rom drives didn't use the Drop in unit from the Dreamcast (but the laser/motor assembly is the same)

so basically, what im saying is the "arcade" GD-ROM System has an interface board the interfaces between the GD-ROM (Dreamcast drive), and the Net Dimm Interface.

I would say it would be more feasable to use an Arcade GD-Rom drive to Dump the Dreamcast discs or arcade discs, then it would be to make a CF adapter for the Dreamcast.

[cybdyn]

never seen before Arcade GD-ROM drive.

i'm developing new scheme of ps/dc emu. if some one interesting in this can fint it on haunted360's PSIO site.

[dark]

As regards the entire thread here - can't one simply do the bios mod and flash the chip with the latest dreamshell release? As a result, dreamshell will boot up on system startup without need for the GDRom drive - and then games could be run from an SD card adapter? Even if this is slightly beyond the comfort range of your typical non-technical DC user to solder in a new chip piggybacking on the bios, wouldn't this be a hell of a lot easier and cheaper than making any kind of hardware gdrom emulator, with the exact same result? And if money was the motivation to do any of this, then this could be offered as a service for the non-technical people to pay someone to install the mod? Sounds like we're already there, pretty much ;)

[sonicdude10]

As regards the entire thread here - can't one simply do the bios mod and flash the chip with the latest dreamshell release? As a result, dreamshell will boot up on system startup without need for the GDRom drive - and then games could be run from an SD card adapter? Even if this is slightly beyond the comfort range of your typical non-technical DC user to solder in a new chip piggybacking on the bios, wouldn't this be a hell of a lot easier and cheaper than making any kind of hardware gdrom emulator, with the exact same result? And if money was the motivation to do any of this, then this could be offered as a service for the non-technical people to pay someone to install the mod? Sounds like we're already there, pretty much ;)

Problem with that is you're limited to a maximum of 32 GB on SD card and it uses the serial connection so load times are rather slow. Some games won't play at all due to how slow it is. That's why we need something to interface with the G1 bus. A person could use any size of HDD, CF or SSD for game storage and load times would be at a reasonable if not insanely fast speed. If the coding supported it, one could use a CD or DVD drive on it and run burned games from DVD or CD to save the precious GD ROM.

[splith]

http://jscustom.theoldcomputer.com/i...omi-GD-ROM.jpg
That's the NAOMI GDROM drive.

[cybdyn]

ye, sd mod for serial connector is more siplest thing for DC now. but it's enough

for non-tenichal users its not big probler unscrew console, and replace the native gd-rom board by emulater, that has same size of geometry and same conector as origianal.