Making a BBA?

katana 9x4 · Post by **katana 9x4** » Wed Jan 12, 2005 9:35 pm

Does anyone know if it would be possible to make a BBA? I am tired of looking around for the stupid things and never finding them, ebay has them occasionely but the prices tend to be rather high by the time the auction is about to end so yea, making one, possible? or no?

blinx3.0 · Post by **blinx3.0** » Wed Jan 12, 2005 9:47 pm

It could be possible but rather hard and time consuming aswell. Its a possability but i wouldnt say yes.

neoak · Post by **neoak** » Thu Jan 13, 2005 12:27 am

You need to reverse engineer the thing to know how it works. Also, because getting the exact version of the Realtek 8139 NIC that the BBA has is probably impossible, a microcontroller might be the solution.

But for now, Nope.

Matt · Post by **Matt** » Thu Jan 13, 2005 10:14 am

Basically what blinx and neoak said. It would be hard, you'd have to find the chip then design somesort of circuit from scratch, or reverse engineer the original circuit and then try to make it compatible with the DC.

Pyrosurfer · Post by **Pyrosurfer** » Thu Jan 13, 2005 2:20 pm

No. Sorry. The bba uses propietary sega chips that are ONLY found on the bba. You could build a 10/100 adapter but it would not be "seen" like a bba (no games would work with it).

neoak · Post by **neoak** » Thu Jan 13, 2005 7:54 pm

Thats why reverse engineering and a programable chip are necessary.

It can be made, but you would need to check the PCB traces and how it communicates. Maybe in 2 years ill give it a shot in the lab when the time is right. The DC scene might be dead, but not for me. The ability to load Homebrew w/o modchip, and Keyboard & Mouse are a plus.

Studying Electrical Engineering. I Love it... but kind of hate math...

However, don't wait for me. Gotta sacrifice a BBA and that is... well... burning money...

Pyrosurfer · Post by **Pyrosurfer** » Thu Jan 13, 2005 9:28 pm

I am pretty sure there is no chance to make a game compatible bba without the sega chip that is onboard. Both the chips on the modem and bba allow pci hardware to be used with the dc. The modem sega chip has 8 PCI bit in, and I think the bba has 16 in. The realtek chip is commonly available, I once had a network card with that chip.

You could use a buffer on the modem chip to get 16 bit in. I think you would need some sort of hacked modem driver though.

I always imagined you could make your modem interface visible as a modem but acting as a bba:
Network Card 16bit interface---> buffer--->Sega Modem chip 8 bit IN<----8 bit Conexant Rockwell Modem chip.

*by using an isa network card buffer may be able to be avoided. I don't think the sega chip was designed for isa though.

Have the network card's power completely cut off at first, and Conexant's on.

Dial up as normal until your dc has been through all the correct modem messages.

Use an instant switching device to turn off conexant, and turn on the network card.

Sega chip will now be "talking" with the network card.

If ethernet is indeed completely "connectionless" I think this might work. Depending on how long it takes a network card to completely power on and recognize stuff you might need to switch the data lines instad.

Your MAC addresses would be different though.

I don't know very much about networking, this was just a thought I had a year ago.

katana 9x4 · Post by **katana 9x4** » Thu Jan 13, 2005 9:53 pm

Well you guys know way more about this than I do it seems lol, and me not being the smartest person when it comes to electronics doesn't help either... maybe I'll just keep searching ebay in hopes that somebody put one up with a reasonable buy it now amount.

Pyrosurfer · Post by **Pyrosurfer** » Thu Jan 13, 2005 10:04 pm

One of the reasons I don't think my idea would work would be the lack of dc drivers for the network card of your choice.

dcmodder · Post by **dcmodder** » Fri Jan 14, 2005 8:15 am

so the answer in a nutshell is no.

JASaxman · Post by **JASaxman** » Fri Jan 14, 2005 3:10 pm

I actually wrote to Sega after recieving an email from them telling me I may be able to get the schematics for it. That was about 3 weeks ago, and still haven't heard back from them.

Does anyone remember that one company many moons ago, that ran one last batch of them? I was going to try and see if they still had the chip dye's, etc, and if they would be able to do another batch if they could get another 1000 pre orders. Its a long shot I know, but you always need something to do while on your lunch break.

Keebler64 · Post by **Keebler64** » Sun Jul 09, 2006 12:12 pm

Has there been any followup on this?

Prophet][ · Post by **Prophet][** » Sun Jul 09, 2006 5:48 pm

there has been talk since I can remember first joining these forums and nothing has ever happened and it never will.

Ex-Cyber · Post by **Ex-Cyber** » Mon Jul 10, 2006 3:02 am

I actually wrote to Sega after recieving an email from them telling me I may be able to get the schematics for it.

Schematics are useless for manufacturing if you can't get the parts, and I daresay you won't be finding the GAPS bridge at Radio Shack.

Prophet][ · Post by **Prophet][** » Mon Jul 10, 2006 4:06 am

You are correct. There are SEGA prepiatry IC's in the BBA which you will not get. You may get a schematic for them if you are a company and pay a third party licence fee which wouldn't be cheap.

Sonic-NKT · Post by **Sonic-NKT** » Tue Jul 11, 2006 1:44 pm

sad thing, i would love to have a BBA...

GyroVorbis · Post by **GyroVorbis** » Tue Jul 11, 2006 2:02 pm

It's very sad. Imagine what you could do if we knew how to homebrew BBAs.

Once we figure out how to get a homebrew online, BBAs could possibly quit being so expensive and hard-to-get. Whoever made the homebrew BBA would certainly make a profit off of it, because who doesn't want a semi-cheap BBA?

Then with the whole scene getting these BBAs, and homebrew games getting online, the Dreamcast's online play could become mainstream again. That would kick ass.

Ex-Cyber · Post by **Ex-Cyber** » Wed Jul 12, 2006 7:34 am

Ross L. wrote:Isn't there a way to figure out the IC's? Or am I not understanding what an IC is.

Yes, they can be figured out, or rather cloned close enough that the software wouldn't mind the difference; the problem is actually making the clone. The main issue is a chip called "GAPS", which is a Dreamcast expansion bus to PCI bridge; the other main chip is a standard Ethernet chip that can be found on almost any $10 PCI card (having the exact version would probably not be necessary; an RTL8139D or RTL8139B shouldn't have any differences that the software would care about if memory serves, and the PCI bridge could likely be hacked to paper over any minor differences). Hobbyists and small-scale manufacturers can "make" custom logic chips at relatively low cost by using field-programmable gate arrays (FPGAs). The problems with this approach are:

- Designing a PCI bridge isn't exactly a weekend project that any random guy can take on

- It's unlikely that GAPS could be cloned in the cheapest devices due to its complexity

- Without a boot disc or BIOS replacement, extra components would be needed to upload the bitstream to the PLD, adding to the cost (unless a flash-based PLD such as the Actel ProASIC series is used, though that's more expensive than Xilinx/Altera's cheaper FPGAs last time I checked)

- A separate SRAM chip would probably have to be added; I think that GAPS has 32KB of internal RAM to use as a transfer buffer for DMA, but I don't see any solid info on this.

Depending on how complex the RTL8139 is, it might even be possible to just fake the PCI aspect and clone the whole thing in a single FPGA (+ SRAM + Ethernet transceiver), but I wouldn't count on that being feasible, and it's not a project that J. Random Hacker is likely to take on any more than cloning a PCI bridge.

Sonic-NKT · Post by **Sonic-NKT** » Wed Jul 12, 2006 1:02 pm

i know almost nothing about all this, but i know that i would pay up to 70-80? for a BBA... and there are many opensource online games which should run on the dreamcast... just thinking about crossfire

if anyone would start to work on it, i would donate!