Setting up GENS (mainly BIOS files related)

Hello gentlemen. I've been having some trouble setting up GEMS to run some games I have. I'm interested in making it run an .iso file which, supposedly, contains a large number of Mega Drive games. I used to run a 16-bit Mega Drive console and got a bit nostalgic.

So, I downloaded the newest release (Gens 2.14 win32 binary) from the official GENS homepage. First thing to note is that, instead of having the folder format described here (the BIOS, BRAM, SRAM etc subfolders) my Gens folder is pretty simple. Here, have a look:



Anyway, I unzipped the .zip file to a newly created C:\Gens directory.

So, after noting this, let's try to play some games. I downladed the Berzerk v 1.00 ROM from the site's main page to test it and it ran fine. It's a .BIN file. However, my original intention was to run the games in the .iso image I downloaded (I mean, come on, it has Sonic 1 and 2 in there), so I tried to open it in Gens (open rom -> choose SEGA CD images -> the .iso file i have) and then I get the message that my BIOS files are not correctly configured.

It's ok, I tell myself, I'll search around a bit. From the GENS tutorial and this thread it is made obvious that I needed to download some BIOS files for 32x and CD gaming and then locate them from inside the emulator. To find a downloading source, I consulted the .txt file included with the Gens package, and it links to this page.

However, my problem is that the only German (?) I know is football-related. =/ Also, that site looks like it's redirecting me somewhere else, and I do not like this.

So, my questions are the following:

1) Is there any other source where I can download the BIOS files from?

2) What's with the lack of subfolders in my Gens folder? Is it ok if I create them myself?

Thanks in advance

Note: I mounted the ISO file I downloaded with Magic Iso and copied its contents on my hd, and noticed that the files corresponding to the games have a .PRX extension. I have been unable to 'open' them on their own from GENS, though.

1). If you read the AUP for this site, rom and bios requests are prohibited here because they contain information that is subject to copyright. Google is the way to go. Although AFAIK if you are using files in the proper format you won't need them as Gens and Fusion only require Bios files for Sega 32x and Sega CD games (which is why its asking you for a bios when you try to run
the ISO as it thinks you are trying to boot a Sega CD game).

2).Its perfectly ok to create your own folders within the gens folder. So long as you use the options menu's to point gens at the relevant ones (roms, bios, etc).

As for your ISO. It looks like you've downloaded a load of Genesis roms designed for use with a PSP emulator.

The specific ISO support in Gens is to play Sega CD games so you won't be able to 'run' an ISO full of Megadrive/Genesis roms. Gens will think its a Mega CD game and just keep reoprting Bios/Disc/Format errors.
You can however run individual genesis roms that have been saved onto a CD/DVD in the same way you could run them from your hard drive.

Your best bet would be to extract all the roms on the CD to a folder (not the ISO but actually the individual rom files it contains). Then download a batch file renamer like THIS one and rename all the file extensions to .bin.

If the roms haven't been modified in any way to run with the PSP, Gens should now read and run your roms.

As a test once you've extracted the roms, right click one, select rename, and change the extension from .prx to .bin. If it boots then you know its worth using the above mentioned batch file app to rename the others.

Its very easy to do. Once you have booted the Batch file renamer, click on the tab that says 'Extensions'.

Now use the bit at the top where it says 'files' to browse to the folder your roms are in, tick the box that says 'change all extensions to' and simply type the word bin in the box next to it.

Now click start and it will rename every rom extension in that folder from .prx to .bin

Hope that helps.

Quite unfortunately, this option did not work. =/ I propably have the wrong kind of ROM.

Edit: Why is it bad to ask where to download the BIOS files from? To my understanding, those files are necessary for the emulator to run smoothly, and they are also referenced in the release notes of Gens.

Jafil21 said:

Quite unfortunately, this option did not work. =/ I propably have the wrong kind of ROM.

Edit: Why is it bad to ask where to download the BIOS files from? To my understanding, those files are necessary for the emulator to run smoothly, and they are also referenced in the release notes of Gens.

Click to expand...

Because a bios is a proprietary, copyrighted IP, exactly the same as a game rom. So legally its prohibited by this sites AUP.

The AUP is there to protect the site, its owners and its users. Although it might seem hypocritical, that is the nature of emulation where people can actively support it and advise on how to do it but have to tiptoe around the murky legal issues that surround the files associated with use of it.