Glitches and emulation errors in Mega Drive, Retrocopy 0.720

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Posted by Sasha on Tuesday, March 23, 2010

#31

Sasha

Type: Member
Posts: 185
Joined: 2/19/2010

I know this type of ROM, just rename MD to SMD and try to run game.

Posted by RetroRalph on Tuesday, March 23, 2010

#32

RetroRalph

Type: Administrator
Posts: 801
Joined: 7/19/2009

No there are different types of file, some .MD are actually different and shouldn't be renamed. It seems MANY of them though can be renamed as they aren't the real .MD file type.

The problem is the no-intro group has decided to use .MD for every type of Genesis ROM out there leaving detection up to heuristics and their own database maybe.

Posted by Sasha on Tuesday, March 23, 2010

#33

Sasha

Type: Member
Posts: 185
Joined: 2/19/2010

I found some info:

http://www.dingoo-digital.com/forums/emulation/sega-mega-drive-genesis-bin-md-smd-converter-found

And some documentations about roms

http://www.emulatronia.com/doctec/consolas/megadrive/genesis_rom.txt

Edited 1 times. Last edit by Sasha

Posted by RetroRalph on Tuesday, March 23, 2010

#34

RetroRalph

Type: Administrator
Posts: 801
Joined: 7/19/2009

I added the ability to set the volume (pre amp) for each of the channels of the PSG Sasha, so that may help you even more.

I already tested that software and it doesn't work on my machine so gave up.

Posted by Sasha on Tuesday, March 23, 2010

#35

Sasha

Type: Member
Posts: 185
Joined: 2/19/2010

Yeah now i can emulate volumes of all consoles, thanks my friend

Edited 2 times. Last edit by Sasha

Posted by Eke-Eke on Tuesday, March 23, 2010

#36

Eke-Eke

Type: Member
Posts: 18
Joined: 3/5/2010

RetroRalph wrote:

Hmm interestingly I was looking at some of the NO-INTRO romsets and noticed that not all .MD files are "Multi Game Doctor" files. Seems they chose the .MD extension and decided to mix up plain binary dumps with the other format. Maybe there are even a few .SMD files in there now renamed to .MD?

I'm not sure who is in control of doing that but it seems like a clusterf*ck. This is what happens when you let ROM dumpers that represent 0.1% of the community try and do their own thing. Why they couldn't be bothered to convert them all to proper .MD files who knows.

Anyhow I will add a heuristic that hopefully will detect real .MD files, the other ones (which are the majority it seems) will already work in RetroCopy v0.720 . As for you, the user that uses no-intro.... well it's not supposed to be easy for you, go check their forums you "rom leach" and you will see what they think of you!

Also if anyone here has a real .MD ROM email me, I couldn't find one and I'd like to have a real world test with one. Seems like a dying format.

.md roms (like .gen ones) are just plain .BIN roms so you just need to add extension support, there is nothing special about them, it's just that some people decided that .bin was not clear enough to designate genesis/megadrive .

You seem to be misleading about No-Intro: basically, it is just a redump project which attempts to check that current existing ROM dumps are correct by redumping all the cartridges themselves, they don't have invented a new ROM format or whatever. In my opinion, this is a great idea because goodgen romset is full of duplicated & alterate roms that are listed as good ones when they shouldn't, or "beta" that are actually full retail games. They also focus on listing only RAW binary dump, that means no interleaved (.SMD), without header, clean dumps. I don't know what "Multi Game Doctor" files are but there are only two ROM format for genesis / mega drive : interleaved and normal. Afaik, No-intro romset only include the later ones.

Edited 1 times. Last edit by Eke-Eke

Posted by RetroRalph on Tuesday, March 23, 2010

#37

RetroRalph

Type: Administrator
Posts: 801
Joined: 7/19/2009

Eke-Eke wrote:

.md roms (like .gen ones) are just plain .BIN roms so you just need to add extension support, there is nothing special about them, it's just that some people decided that .bin was not clear enough to designate genesis/megadrive .

Not according to this :-
http://www.zophar.net/fileuploads/2/10614uauyw/Genesis_ROM_Format.txt

cart.txt wrote:

Multi Game Doctor file-format (.MD):
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

The MD file format also doesn't have a header. The interleaving it uses
is equal to the SMD, but without the division in blocks! (Even bytes in
the end of file, odd bytes in the beginning).

THE DECODING A MD (how to convert a MD to a BIN):

1) Get middlepoint (size of rom/2)
2) Get a byte from the ROM
3) If the byte position is equal or smaller than the middlepoint put the
byte in byte position*2 of the destination buffer
4) If the byte position is greater than the middlepoint, put the byte in
(byte position*2) - size of rom -1

Yes well the problem is they chose .MD which is used by an existing format (at least according to that document).

Posted by panzeroceania on Tuesday, March 23, 2010

#38

panzeroceania

Type: Member
Posts: 68
Joined: 8/31/2009

to clarify things, I wasn't referring to the game doctor format, but the name that the No Intro set uses.

It may be just a name, but it's the form my roms come in every time I update.

I use them because they are the most up to date source of clean roms, I don't touch the goodtools sets with a 10 foot pole, and the TOSEC guys are excellent (they actually redump everything and verify it themselves) but they don't release as often and don't have complete sets, No-Intro is complete and constantly updating.

In any case, I didn't mean for this to become a rom source preference debate, it's just that as of right now Retro Copy doesn't recognize the format and there is no way to force it to see them, which is why I brought it up, as mentioned previously it should be an easy fix.

as for the Multi Game Doctor, I don't know of anyone who uses it regularly anymore but I could be wrong .MGD or .GD would seem to be a more logical name in any case.

but yeah, I hope that clears things up, they should be binary data as far as I know.

I wouldn't bring it up if it was just myself, many people use No intro sets for all sorts of system because it's became a name associated with clean files.

Edited 1 times. Last edit by panzeroceania

Posted by RetroRalph on Tuesday, March 23, 2010

#39

RetroRalph

Type: Administrator
Posts: 801
Joined: 7/19/2009

panzeroceania wrote:

In any case, I didn't mean for this to become a rom source preference debate, it's just that as of right now Retro Copy doesn't recognize the format and there is no way to force it to see them, which is why I brought it up, as mentioned previously it should be an easy fix.

I'm fairly sure .MD (in extension) support is in v0.720 . Such that if a .SMD/.GEN/.BIN file are renamed to .MD it should be detected fine. Have you tried that version?

Posted by Eke-Eke on Tuesday, March 23, 2010

#40

Eke-Eke

Type: Member
Posts: 18
Joined: 3/5/2010

RetroRalph wrote:

Yes well the problem is they chose .MD which is used by an existing format (at least according to that document).

Well, this is strange, I never seen a .MD rom before until no-intro people decided to use it and it popped ups everywhere with users requesting .md support.
I think this is a mispelling error in this old document and in fact, according to ucon (a ROM converting utility), Multi Game Doctor format name is MGD (http://ucon64.sourceforge.net/ucon64/readme.html).

What is sure is this is not a very common format (I don't think any of the ROM websites has this kind of format anyway).

Posted by RetroRalph on Tuesday, March 23, 2010

#41

RetroRalph

Type: Administrator
Posts: 801
Joined: 7/19/2009

Eke-Eke wrote:

Well, this is strange, I never seen a .MD rom before until no-intro people decided to use it and it popped ups everywhere with users requesting .md support.

What exactly does ".MD support" mean then? Just the extension type to a rom browser?

Going from the searches I've done some people indeed do have these Multigame doctor files and they referenced them as .MD . This is before No-intro were doing what they are currently doing.

Eke-Eke wrote:

I think this is a mispelling error in this old document and in fact, according to ucon (a ROM converting utility), Multi Game Doctor format name is MGD (http://ucon64.sourceforge.net/ucon64/readme.html).

What is sure is this is not a very common format (I don't think any of the ROM websites has this kind of format anyway).

I think it's both (.MD and .MGD) , there is a thread on the nointro forums about it and the confusion it has caused. I don't think it's very common either but they are still out there. I'd like to see one to test my heuristic for it.

I just think it's bad form for them to come up with something "new" which is taking over something "old", especially when it comes to a header-less file extension. If they are going to take over .MD they should have made them like the .MD format, at least it would be unified then.

Posted by Sasha on Wednesday, March 24, 2010

#42

Sasha

Type: Member
Posts: 185
Joined: 2/19/2010

Friends, it just changed extension from SMD to MD, some guys ask AamirM add MD extension, and it nothing change in detection of ROM, some people for their tastes rename SMD to MD

Extension GEN it tastes of people too, original extension is BIN'aries

Posted by RetroRalph on Wednesday, March 24, 2010

#43

RetroRalph

Type: Administrator
Posts: 801
Joined: 7/19/2009

It's more than a cosmetic thing Sasha. You can't rename REAL .md files to .smd and expect them to work.

http://forums.no-intro.org/viewtopic.php?f=2&t=527&start=0

UpThorn wrote:

As the current maintainer of the TAS community branch of the Gens emulator, it has recently come to my attention that the no-intro tool renames Genesis/Megadrive rom files to use the .MD extension.
This is bad because .MD corresponds to a specific file format where all the even bytes of the ROM image are in the first half of the file, and all the odd bytes are in the latter half. While .MD no longer seems to be in common use, any emulator that still supports it properly will choke on a no-intro renamed .MD file. Please change the tool to rename .BIN files to .GEN instead.

BladeArts wrote:

No-Intro uses the most natural extention and most accurate ROM format. It may conflict with previously established standards but No-Intro uses its own convention and standards. So it's not a mistake, just a different standard. Emulators such as KEGA Fusion and MESS have integrated No-Intro's new standard.

So they are stating they don't care if it conflicts with previous standards. This is what I am saying is bad form, when it comes to headerless files like ROMs being able to detect what you're looking at is important. The only safe way to do this with headerless files is the extension.

Posted by Sasha on Wednesday, March 24, 2010

#44

Sasha

Type: Member
Posts: 185
Joined: 2/19/2010

I just think what this feature may cause bugs, Record input very hard thing

but it will be very cool when few TV set's show recorded game play.

Edited 3 times. Last edit by Sasha

Posted by panzeroceania on Wednesday, March 24, 2010

#45

panzeroceania

Type: Member
Posts: 68
Joined: 8/31/2009

[quote=RetroRalph]

panzeroceania wrote:

I'm fairly sure .MD (in extension) support is in v0.720 . Such that if a .SMD/.GEN/.BIN file are renamed to .MD it should be detected fine. Have you tried that version?[/quote]

I haven't yet but I will ASAP, I remember it didn't recognize them in 0.700 though which was a bother, glad to hear you fixed it, I will test it and get back to you when I can.

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