Is there a simple way to dump a Mega CD 2 bios? Preferably a method which doesn't involve removing the EPROM.
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Is there a simple way to dump a Mega CD 2 bios? Preferably a method which doesn't involve removing the EPROM.
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.
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.
I just want to dump a potentially undumped bios.
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.
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.
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.
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).Quote:
Originally Posted by BKK
I don't have the unit yet, hopefully it should arrive next week.
Out of interest, what kind of unit is it, and how do you know it has an eprom?
Well keep us informed, my interest is piqued at least ;)
Yes, I'll post when I have more info.
Well, it's something new.
Ver 1.11
From a prototype unit dated 92.9.25
http://i.imgur.com/9ASQ89H.jpg
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.
Attachment 11575
NEC JAPAN
D27C1024A-12
9025K9002
EPR-
V1.1
283?
Attachment 11576
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...
Yeah, the "EPR-" was printed on the sticker, the "V1.1 283?" (I think the last character is Japanese) was hand written.
I also got a MD2 with it, the shell has some differences to the the retail release, but the board seems to be final "PC BD MD2 VA0", "171-6349B" (I can't actually find any references to that part number, but maybe it just hasn't been documented yet). The latest chip I could see on it was 9233, or middle of August 1992, so from around about the same timeframe as the MCD2. Despite both MD2 and MCD2 not getting released until April 1993, MD2 seems to have been a bit further ahead in terms of development. There are MD2s with 1992 serials, but the earliest MCD2 serials are 1993 ones.
Yes, it shouldn't be difficult to dump, but I'll see if I can get it done myself first.
Also, Asian NTSC Multi-Mega (MK-4121-07) and Linguaphone Education Gear (They're essentially the same thing) have a version of 2.21, but with 1994 copyright, so a different version than CDX and PAL Multi Mega (MK-4121-50) which have a 1993 copyright. So that's at least one more that is undumped (assuming that they share the same version).
Interesting, it just occurred to me that I've never seen any Japanese MD2s or MCD2s disassembled, so I can't tell if any of those numbers are early or not.
Nor any for the Asian Multi-Mega or the Linguaphone, but those are way outside my budget.
Here's the earliest VA0 JP MD2 board picture that I could find online (right click>view image for full size);
http://i.imgur.com/BFDm5g3.jpg
The latest chip that I can see on that is 9246, or November 1992.
Here's mine;
Attachment 11578
Attachment 11579
Actually looking again, whilst the board appears to be the same, the chips have different part numbers and manufacturers.
As for Asian Multi-Mega and Linguaphone Education Gear, the former isn't that rare. Going by serial numbers, at least 5,000. Compared to 20,000 for Europe/PAL, and 90,000 for CDX. Apart from the model number, Asian Multi-Mega looks like a European one, so one might come up cheap. I'll keep an eye out for one, I'm sure it will be a lot cheaper than what I paid for these :P.
For Linguaphone, yes, they really are rare, out of the few serials that I've seen, maybe in the hundreds, and to make matters worse, I don't think they were sold to consumers. Whilst researching that I came across some software for it, which I don't think has been documented in English before (and only a handful of pages in Japanese). I created a page on segaretro about it. It seems that even less of that survived than the hardware.
It's not that those Multi-Megas are rare, it's that they are very expensive... They are up on ebay all the time.
Well, it's all relative, but this Asian one (+ games) went for $150 a few months ago, and that was listed as Asian. I think that's reasonable, and loose PAL ones can go for cheaper, so I think with patience, and a keen eye then it should be possible to pick one up for a reasonable price. I'll be keeping an eye out anyway.
I dumped a Japan very early Mega CD BIOS a while back after someone asked about it, but no one seemed to want the file.Quote:
Originally Posted by Mad Moham
There is a thread on here where i offered it, i had asked about region free BIOS inistially.
Which one was it? I'm interested.Quote:
Originally Posted by CasetheCorvetteman
Let me find the thread.
Here it is:
http://www.sega-16.com/forum/showthr...gion-free-BIOS
Further on in that thread i have a photo of it.
Ah, I see, it was the Rev B chip. I do have that, I'm not sure if it was from you though (hard to keep track). Either way, thanks for dumping it, it's an EPROM so having more dumps of that confirms that the chip did not suffer any data loss.Quote:
Originally Posted by CasetheCorvetteman
I've got a MCD2 if you'd need pictures or something, but right now it's in storage and a bit out of my reach.Quote:
Originally Posted by zyrobs
Interesting find on this early MCD2 though BKK, definitely looks unique.
That unit looks like a prototype for the Funai manufactured MEGA/SEGA-CD unit.
CDD is the microcontroller chip which drives the CD drive. It's a 4 bit CPU with a embedded ROM program which defines the behavior of the drive. The prototype has a sticker with the code "PU300" written on it's CDD chip. A couple minor patches (a small breadboard with a small transistorized circuit patch and few wires) probably to fix minor design errata. The heatsink also is too small for that design, which suggest they noticed it was insufficient and later got reworked to have the much bigger area we see on final units.
There are units with Hitachi (JVC drive on SEGA/MEGA-CD1), NEC (uPD75006) and SONY (CXP5084) CDD. The BIOS made for units with NEC CDD (Wondermega 2, X'Eye, Funai SEGA or MEGA-CD) will not operate on a board with SONY CDD as detailed at the service manual. BIOS for systems using the SONY CDD work fine anywhere.
Have you managed to dump the BIOS?
Yup, I'd definitely like to see pictures, the more the merrier.Quote:
Originally Posted by xelement5x
Thanks for your input, I haven't had the time this week to spend on attempting to dump the BIOS, but hopefully I'll have a bit more time next week. Failing that I can always send the EPROM to someone else to dump. All Japanese Mega CD2s were manufactured by Funai, so presumably none use the Sony CDD. Incidentally, the earliest Sony Sega CD model that I've seen was from August 1993, so quite some time after Funai started manufacturing them. I guess that's when Sega issued the "Differences between Funai and Sony" Sega/Mega CD units technical document.Quote:
Originally Posted by l_oliveira
So it's probably a good idea not to use this too much? Fortunately I've only had the opportunity to use it for a short time for testing on the day that I received it anyway.Quote:
Originally Posted by l_oliveira
Well, I gotta comment that the CD1 has a small heatsink but the IC it uses for 5V conversion is slightly better in efficiency department than the plain 7805 IC.
I would avoid using a prototype console as wearing it down you are reducing it's value. It's a historical item. ;)
Yeah, I wasn't planning on using it very often. Bios dumped now;
http://assemblergames.com/l/threads/...er-1-11.64045/
If you still have it disassembled, could you please make some screenshots of various parts of the board, and the ICs? Especially the bios chip, I can't quite read the markings on it.
edit: does the Megadrive have a serial sticker on its back?
Yeah, I'll document the various ICs when I get the bios chip back. The Mega Drive doesn't have any stickers on it.
Sounds great!
And thanks for dumping and sharing the bios chip!
Could you be more specific on which bytes need to be read from somewhere else?Quote:
Originally Posted by Mask of Destiny
I wrote a dumper
http://www.sega-16.com/forum/showthr...CD-bios-dumper
and my dumps are either undumped versions or suffer for the problem you mention.
From what you say I believe it's the latter, so I'd like to fix that.
You plan to update your "suite" what good news, on this subject an option of the choice of the communication port (controller port 1 or 2 and "ext" of the firsts md...) would be welcome !Quote:
Originally Posted by Mask of Destiny
anyone that have this file can repost now that assembler is dead?Quote:
Originally Posted by BKK
edit: nvm, its here
https://segaretro.org/Sega_Mega-CD/Boot_ROM
It should be noted however, that this is not in any way a prototype model 2 bios. 1.11 is just the last version of the original model 1 japan bios. and its a really rare version. I've only seen it in an actual japan model 1 once in my life. I believe it was never on factory units, and only found on units that were sent to sega for repair.
https://segaretro.org/images/2/2e/Se..._Bulletins.pdf
lists the header of the last japan model 1 cd bios, the checksum given $f074, is the same as this. So its definitely not a prototype model 2 BIOS.
actually my mega CD is V1.11 model 1 interesting that it could be a refurbished unit from Sega how did you come to that assumption? I can confirm that it contains the JVC laser and the main board is slightly different with an extra populated Chip ( top right ) which is left out of a PAL UK unit which just has the empty space on the main board see PhotoQuote:
Originally Posted by deadscreem
Attachment 15372