Dumping Bioses

[BKK]

Is there a simple way to dump a Mega CD 2 bios? Preferably a method which doesn't involve removing the EPROM.

[xelement5x]

Is there a reason you need an original dump? Most of them have been around for awhile.

You may be able to do a rom dump with a flashcart and utility, but I've never seen anything like the talked about really.

[Mad Moham]

As far as I'm aware, every version of the CD bios has been dumped already and isn't hard to find.

Can you explain what you need it for? If you're just trying to reflash another CD unit then you're probably better off with one of the dumps that's already been made available.

[BKK]

I just want to dump a potentially undumped bios.

[BKK]

Anyway, I've found two methods;

http://www.retrodev.com/transfer.html

Unfortunately version 1.1 which supports dumping bioses only has files for US Sega CDs. Maybe that just needs the region code changing.

This old flash cart also seems to support dumping the bios.

http://products.genny4ever.net/megacart_v1x.html

I'm not aware of any modern flash carts which support dumping the bios.

[Mask of Destiny]

My "Transfer Suite" works fine with my region converter tool. Be warned that there is a small flaw in that there are a couple of bytes from the BIOS that are overridden by a register value when read from the normal address. I should really update it to read from a mirror instead. This doesn't really matter for actually using the dumped BIOS, but if won't technically be bit perfect to what's in the ROM.

For what it's worth, it should be pretty straightforward to write a dumping tool for a more recent flash cart, especially one like the Mega Everdrive that has a USB serial connection.

[BKK]

Oh, cool, thanks for responding. I'll go ahead and make a cable. If the bios is something new then I'll eventually need a good dump for the sake of preservation, but a bad dump should be enough to see what bios version it is.

Yes, I thought that there might already be a dumping tool for modern flash carts, which is why I started this thread. Well, I don't have a flash cart, but it's something that I should probably get anyway.

[zyrobs]

I just want to dump a potentially undumped bios.

Can you post a photo of the actual rom ic? As far as I know the only undumped ones are on alternate region multi-megas (if they even use a different bios), and a few very early mcd1s (those had a LOT of revisions, not all are dumped).

[BKK]

I don't have the unit yet, hopefully it should arrive next week.

[zyrobs]

Out of interest, what kind of unit is it, and how do you know it has an eprom?

[xelement5x]

Well keep us informed, my interest is piqued at least

[BKK]

Yes, I'll post when I have more info.

[BKK]

Well, it's something new.

Ver 1.11
From a prototype unit dated 92.9.25

[BKK]

It's basically a JP MCD1 bios, even down to the open option (which obviously doesn't work). Region locked hardware and software. Lots of hand written stickers on the chips. Board "E2200JAPCB", I'm guessing lots of differences to the initial retail board, but can't find any pictures of a JP one. My spliced up cable didn't work correctly, so wasn't able to get a usable dump. I'm going to order some connectors and make a proper cable. I'll make a thread with a more indepth look once I get the bios dumped.

IMG_4385.jpg

NEC JAPAN
D27C1024A-12
9025K9002

EPR-
V1.1
283?

IMG_4395.jpg

[zyrobs]

Wow, a lot of patch work on that board, looks like one of the chips was even reflown (or replaced).

Note that the "EPR-" part is possibly not part of the chip ID. While Sega indeed uses that prefix for eproms, it seems they only do it for data that went into production - prototypes don't get that identification. But, the EPR- text stays there, because it was their standard sticker to put on eprom windows.

The chip is socketed, so I'm sure that plenty of people could dump that for you, in case you can't handle it. Don't remember anyone in the USA from the top of my head, though...