Help with new BBA adapter (cont. from Cluster)

[semicolo]

Well the transfer speed shouldn't be a problem since the dc G2 bus is 400 Mbps when ethernet is 100 Mbps, it should be ok with some buffers.

I've got 2 or 3 ethernet cards with a realtek 8139 too.

[RangerGuy]

OK, I checked the NIC card I have, and unfortaunately, it is not the same chip. However, when I get the opportunity, I will take a picture of it, and post it.

[semicolo]

one could use the realtek 8100 too, it's the same as 8139 but has physical layer integrated, with the same problem of interfacing it onto the G2 bus and obtaining the chip in small quantities.

[wiatr]

If the homebrew BBA is feasible, I think that we would instead have to obtain the chip in huge quantities, since every single DC owner would probably ask for one.

Any idea of how much a homebrew BBA would cost (supposing the G2 / Realtek interfacing coud be easily solved) ?

I also wondered, since the modem extension is included by default in each off-the-shelf DC package, if it could be possible to re-use the modem extension, but twist it to interface itself with a realtek system to go ethernet.

What do you think about this?

[Alexvrb]

I find it very unlikely that the masses would be interested, especially because it could never be cheap, affordable maybe, but not cheap enough to buy on a whim. Anyway, you still might need to buy in fairly large quantities, depending on the chip. A lot of times there's a relatively large minimum order, you know? So unless you can scavenge from cheap PC networking hardware, no individual could really get it rolling anyway. But that's assuming someone had a design for a fast, simple ethernet interface.

[semicolo]

Supposing the G2 / pci can be done by a CPLD and we make about 100 boards, these two pieces of hardware would cost about 15 US$ (and a realtek ethernet pci card can be found for 10 US$ I think).

Well not a bad idea for the modem thingy, we'll have to figure if the chip used are pci ones (like in winmodems) and if it's the case reuse the bridge. Darn I think I dumped mine already...

[Mental2k]

so could we load on homebrew using this?

[Chaotis]

I'm still here, just been out of town snowboarding for a few weeks. Also have several other projects on my hands so any work I've done has been really slow.

I still haven't been able to find any other networking chip for sale that doesn't have a minimum quantity of like 500+ so if anyone knows of one please let us know. I guess the other way to go is find a common ethernet card and use it (or pieces of it)?

Just a passing thought, anyone think it would be worthwhile to just build a g2 to pci adapter and use an ethernet card to do the rest of the work? I don't mean trying to build one where you could put any pci card into it, just an ethernet card or perhaps several different ones unless they are very different hardware wise. No idea as to the difficulties in this idea. :-/

I went through all of my spare hardware, and in about 8 ethernet cards I didn't have any realtek ones. x.x

[STC-Fan]

Crikey... never in my right mind did I imagine anyone else would have thought of actually trying to build a replacement BBA! But that's mainly because up until now I've only been visiting the B00B! DC Research forums which are sadly rather idle :P

Not that I'm trying to build one, but I have thought about it on occasion, including the idea Chaotis mentioned, though it would probably be quite hard to do. Having said that, getting the pinouts for a PCI port would be handy to start with. I just did a Google Search and came up with this.

(EDIT: And I suppose a pinout for the BBA connector would be very useful as well, though I couldn't find that on Google. A bit of DC reverse-engineering would probably be needed to produce details like that.)

[semicolo]

Well I started thinking of using a cpld for bridging the G2 to pci
I found some verilog source on the Internet (copied there : ftp://semicolo.homelinux.org/dreamcast/verilog.php.html)
Credits go to Ben Jackson.

In early thinking for now (well in fact I've got all the needeed hardware but the pci connector)