MD Undumped 26.05.09

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ElBarto
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Re: MD Undumped 26.05.09

Post by ElBarto » 03 Dec 2009 21:13

I didn't know if the one we had before was the one present in goodgen, I've checked it's the same so both are good dump.

kiddocabbusses
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Re: MD Undumped 26.05.09

Post by kiddocabbusses » 04 Dec 2009 02:32

Ah, so we have both the US SC BIOs after all? Thanks. :D

I've been trying to look for a Japanese Sega Channel cartridge in my typical import locations, but while I have pictures of what the set looks like I've not seen it for sale. I'd also suspect that there's a version of Sega Channel for PAL Regions. Could anyone try to check on that?

As for the Demo cart, best to give it it's full title "Sega Channel Demo Cartridge #4 (dated 2-16-94) (USA)".
Based on the date of the cart's label and some findings at Sonic Retro, I'd be tempted to classify it as a Prototype, as well.

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ElBarto
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Re: MD Undumped 26.05.09

Post by ElBarto » 04 Dec 2009 09:00

There is not japanese sega channel cart, only the game toshokan one (confirmed by myself).

The Sega Channel was also available in UK (I've myself bought mine there) so maybe there is a different bios (mine is 1.7)
And this cart is not a proto, it's really a demo that show you how long you have to wait for a game etc ...

kiddocabbusses
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Re: MD Undumped 26.05.09

Post by kiddocabbusses » 04 Dec 2009 22:42

Game toshokan?
Could you explain that a bit better?
(and also, the two blog posts I linked before with the unique-looking BIOs cartridge?)

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ElBarto
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Re: MD Undumped 26.05.09

Post by ElBarto » 05 Dec 2009 02:34

Just seen those two links, so there was a sega channel released in japan ..... didn't know that.

The Game Toshokan is the cart that use the modem to download games.
Almost or all the games available were re-release on the "Sega Games Can Vol. 1" and "Sega Games Can Vol. 2" on the megacd.

kiddocabbusses
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Re: MD Undumped 26.05.09

Post by kiddocabbusses » 05 Dec 2009 17:15

Ah, the MegaNet service. thanks for explaining.

Anyway, yes, I was linked to a picture of the JP Sega Channel BIOs by a friend at Hidden-Palace.org and went to research from there. Besides those pictures, I've read these game titles referenced as explicitly related to the Japanese Sega Channel somehow;

1) Dyna Brothers 2 Special; seems to be a special modification of the original game with some new modes and features, which I've noted as being on the Japanese Virtual Console. The rest of these, I'm not sure of any difference from whatever respective versions are out there.
2) Earthworm Jim 2
3) Ecco Jr.
4) Pitfall - The Mayan Adventure

I was also linked to the "Game no Kanzume Otokuyou" ROM, which I heard was ripped from the Dreamcast "Dream Passport 3" ISO, and it explicitly has a variation of the Japanese Sega Channel Logo on the title screen, leading me to think that is also related.

I'm still researching more, since I like gathering this info up. Maybe it'd be useful for a database of some sort, if we get enough Sega Channel content that it would merit such.

eke-eke
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Re: MD Undumped 26.05.09

Post by eke-eke » 28 Nov 2010 18:22

ElBarto wrote:
michal99 wrote:
BigFred wrote:michal, do you dump MD with an EEPROM reader? TheGuru told us long ago the direct reads he did from genesis carts were byteswapped. If so I'm pretty confused on this matter.
I did few test dumps and yes they are if I remember right. I did discuse that with Elbarto, but I would have to look what whas the result, tho.
Yeah of course MD games are byteswapped. Like all the rom from a big endian system (Neo-Geo for example).
The thing is changed that now is impossible as all emulators are waiting for byteswapped roms.
But this isnot really a problem as we can byteswapped them at any moment.
Sorry to bump that old thread but i was doing some research about md ROM dumps and i've actually read that statement a few time.

Problem is this makes absolutely no sense to me. Why should it be logical that ROM are byteswapped ? The 68k cpu access the ROM as word and would not decode instructions correctly if they were byteswapped (i.e not in their original order). You might argue that current dump are not in the correct order but again this is not true: just look at them in an hex editor, instructions are in the correct byte order i.e big endian (msb first). My emulator is running on a power pc architecture and does not need to do anything special to read 68k instructions as word from ROM, contrary to PC emulators (indeed, since 16-bit instructions are stored in big-endian format, ALL pc emulators already have to byteswap them at one point or another).

I only see 2 possibilities that could explain eprom dumps are byteswapped from known dumps:

1) the cart pcb has data lines mixed (D0-D7 on md side wired to D8-D15 on mask ROM side). Has anyone ever checked that ?

2) the dumping software is byteswapping word itself when writing the output file: i have no idea how this kind of tool works but i guess it's very configurable to work with any possible chip.

michal99
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Re: MD Undumped 26.05.09

Post by michal99 » 30 Nov 2010 21:45

Yeah of course MD games are byteswapped. Like all the rom from a big endian system (Neo-Geo for example).
The thing is changed that now is impossible as all emulators are waiting for byteswapped roms.
But this isnot really a problem as we can byteswapped them at any moment.
Sorry to bump that old thread but i was doing some research about md ROM dumps and i've actually read that statement a few time.

Problem is this makes absolutely no sense to me. Why should it be logical that ROM are byteswapped ? The 68k cpu access the ROM as word and would not decode instructions correctly if they were byteswapped (i.e not in their original order). You might argue that current dump are not in the correct order but again this is not true: just look at them in an hex editor, instructions are in the correct byte order i.e big endian (msb first). My emulator is running on a power pc architecture and does not need to do anything special to read 68k instructions as word from ROM, contrary to PC emulators (indeed, since 16-bit instructions are stored in big-endian format, ALL pc emulators already have to byteswap them at one point or another).

I only see 2 possibilities that could explain eprom dumps are byteswapped from known dumps:

1) the cart pcb has data lines mixed (D0-D7 on md side wired to D8-D15 on mask ROM side). Has anyone ever checked that ?

2) the dumping software is byteswapping word itself when writing the output file: i have no idea how this kind of tool works but i guess it's very configurable to work with any possible chip.
I don't know about the 1, but 2 is definitely no. First you're dumping the data directly from the chip itself and the software display the data as it read. Sure you can save them after as you like.

eke-eke
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Re: MD Undumped 26.05.09

Post by eke-eke » 01 Dec 2010 09:21

but 2 is definitely no. First you're dumping the data directly from the chip itself and the software display the data as it read. Sure you can save them after as you like.
Again, I don't know much about ROM dumping software so this might be completely irrelevant but the fact you are dumping directly from the chip does not solve the fact you are using software running on a little-endian machine (most likely) to display big-endian words.

Does software display the state of each bits / data line or directly shows a 16-bits word ? In the later case, I guess it depends how software interprets the data lines to output the word value. I know that flashing software have options to specify the endianness when writing words to the chip so maybe if you set to big-endian and 16-bit mode, words will be read as big-endian (LSB in D0-D7, MSB in D8-15) but displayed in platform native format, i.e little endian.


Anyway, the fact is, 68k is big-endian and so are instructions words stored inside current ROM dumps.
If data in mask ROM was byte swapped and words stored in little-endian, it means bytes MUST be swapped somewhere before reaching 68k data lines.

I've looked at a few cartridge and, providing the mask ROM pinout is conventional (and I guess it is if you are using direct EPROM dump), Data lines are NOT inversed but properly connected, so there is definitively no way byteswapped ROM is the common format. If my logic is wrong, please someone correct me because, as much as I understand you guys know what you are doing and are trusting your dumping hardware/software, I don't see any valid reason that could explain genesis ROM are stored in little-endian internally, this simply does not make any sense to me

z.g
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Re: MD Undumped 26.05.09

Post by z.g » 01 Dec 2010 10:05

in sonic classic collection roms in big endian:
Image

eke-eke
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Re: MD Undumped 26.05.09

Post by eke-eke » 01 Dec 2010 10:34

This ROM is stored in little-endian format, not big-endian.

And if you think about it, it makes perfect sense: Sonic Classic Collection on NDS uses an emulator with the original ROM data.
But NDS CPU is little-endian so they stored the ROM in little-endian format (i.e byte reversed) since the emulator 68k core need to read & decode instructions as words.

This is basic optimization done by emulators running on little-endian platforms (like PC), as I previously explained. In any case, this does not means the original format is like that, it's just the way they stored the ROM data for emulation purpose.

z.g
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Re: MD Undumped 26.05.09

Post by z.g » 01 Dec 2010 11:52

eke-eke wrote:This ROM is stored in little-endian format, not big-endian.
of course :)
with the original ROM data.
it is not original. it seen even on screenshot. in original rom data at offset is GM 00001009-00&J, here GM 00004049-019M. and extracted rom doesnt' work on pc emus.
ps: my post was not as any argument but simple information.

arromdee

Re: MD Undumped 26.05.09

Post by arromdee » 11 Dec 2010 17:49

http://forums.sonicretro.org/index.php?showtopic=21916 reports a dump of a pirate cart several months ago which doesn't seem to be in the database. It seems to fall into the category of mostly original pirates that only use someone else's license and a couple of assets. Should it be included?

The thread also reports a few other recent dumps.

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Macarro
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Re: MD Undumped 26.05.09

Post by Macarro » 29 Jun 2011 08:12

Star Odyssey, recently released

http://www.starodysseygame.com/index.html

MikeHaggar
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Re: MD Undumped 26.05.09

Post by MikeHaggar » 29 Jun 2011 08:39

gigadeath wrote:Other than Beggar Prince, there's Legend of Wukong too, but the latter is too new, dumping and releasing it would be very bad manner...

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