Multi-Mega / CDX switchless region free mod + Mega Amp

Hi

2 months ago, someone did the switchless mod on my Multi-Mega (this one http://wolfsoft.de/wordpress/?p=478)
The mod is working great, but there's a twist: the japanese and European Megacd bios won't load automatically by themselves, instead I get the region error message... But when I use an Everdrive, and press "Run CD" from its menu, then the selected bios and game loads perfectly. So the bios are there, they just need a little help to boot.
No problems with US bios and all carts from every regions are accepted.

I noticed as well that when you press on the reset button to change the region, Euro loads in 60hz by default, US as well, but Japan loads in 50Hz, and that would be great if it was changed to 60Hz by default too. You have to shortly press the reset button to switch between 50 and 60Hz.

I contacted the guy who mod the console, and he's going to check inside and post some pictures.
Does someone here have a clue about what can be wrong? This is an amazing mod but it's a bit annoying to have to use the Everdrive to boot...

Also, I wonder if someone here knows if it's possible to install the Mega Amp on a Multimega?

 

x

 

No it's a Multi-Mega, not a CDX. Indeed this mod is very clever, but also quite difficult to make. The wiring seems ok, but I'll ask the guy to double check the wiring he did to the US bios (the one that work) and compare it to the 2 others that don't boot. But again, when I run the Multi-Mega bios from the Everdrive menu (NOT from a bios FROM the Everdrive), everything work, so it is very weird. What do you mean by "the PIC is programmed wrong"? Could it be that the 2 faulty bios have problems while the US one is ok?

 

Hi,
I've just finished a switchless Megadrive + 32X + MegaCD, so I suppose the MultiMega switchless is somehow similar.

The PIC is the small chip which is running the program cycling trought US->JAP->Eu for the language and the video output, and can also do the same thing for the bios of the CD part.

What intrigues me is your JAP50Hz since if Wolfsoft is using the same PIC code as the Megadrive switchless from Seb is not possible.
I think there's a mix up between PAL60hz and Jap50hz.

It can be 2 wires inverted or the order of the multibios "usa.bin + pal.bin + jpn.bin" which is different from what I used if I remember correclty (USA --> JPN --> EUR).
I'll check that.

EDIT: Yes, I used the USA-> JPN -> EU (then Columns in my case) order.

Edit: Yeah I think I get it. There's 2 PIC code for the switchless Megadrive: the Seb's code (from the Saturn's mod) and the Dforce3000 (http://www.dforce3000.de/?uid=12). They don't need the same order for the mutlibios.

 

Ok, so you mean it's somehow the PIC that is not programmed correctly, in the right order? We used the Seb code. Should we try the other one?
When I said that Japanese bios booted in 50hz, I meant that it was the default setting, but if you press the reset button it switches in 60hz. All the other bios boot first in 60hz, then by pressing reset it switches in 50hz, but the Japanese is 50hz first. Which is annoying.

Here is some pics of the switchless mod, under construction:

 

Here's some more:



What is weird is that if the PIC code is the problem, and the order usa.bin + pal.bin + jpn.bin is wrong, how is it possible that when I start the CD from the Everdrive menu, then the correct bios is loading without issues?

 

Hi,
Sorry for my bad english.

There's 2 points in this mod:
- The PIC16F630 which is running the cycling program between video and language (NTSC US / NTSC JAP / PAL 60).
- the 27c4002 Eprom (I use a 27C4096 for mine) for the BIOSes of each region.

When you'are cylcing trought the video/language mode, you also send info to pin 38/39 of the bios. Yellow and blue wire here:


So when you are cycling to each mode, you are sending to the bios in logical binary: 0/0, 0/1, 1/0 (and eventualy 1/1, and don't know really well how seb's code is working) so you are cycling also between BIOS of each regions. But you have to program the Eprom with the BIOSes in a specific order

To me it is either:
- yellow and blue wire are inverted in your console
- the order of the BIOSes in your Eprom and the program in your PIC are not matching. (result that it's trying to load a japanese CD bios when your console is in 50hz and you got your region error).

 

x

 

It's a spaghetti mod because Wolfsoft use somehow the same piggyback method as Mmmonkey (here).

By replacing the whole thing with a single Epprom it's much tidier (like mine here)

 

Ok, so would that be possible to re-programm the epprom with a region free bios instead, or is that more complicated than that?
The Multi-Mega is very different than a Mega-CD, and that's maybe the reason why Wolfsoft is somehow using that method.

We'll first try to correct the problem by checking the order of the bios, and if the cables are inverted, as you pointed out. It look like it's something like that, cause I can see that the order of my Multi-Mega is US -> EUR -> JAP, and not US -> JAP -> EUR... which could explain why my Japanese bios is loading in 50hz by default.

 

The mod seems identical from what I'm seeing:
- JP1/2/3/4 are for language/video mod when they have +5V or are grounded.
- PIC16F630 cycling by reset switch
- Dual LED
- piggyback Epprom
- additional line for 32x via A/V output

The only difference I could see is Mmmonkey (and me) has to use an signal inverter.
Let's say I want US console with a US CD bios: I need +5V/+5V on the JP, but 0/0 on the bios.

From what I read on Wolfsoft, they don't use it. They wrote:

and I don't understand this part and it seems contradictory. I'm still at work I'll take a look mor closer at home.



Edit: A quick fix could be measuring your yellow and blue wire on your Eprom and see in which order they alternate between +5V and 0 (after checking you have not invert them).
From that you will be able to program your BIOSes order accordingly to your PIC.


Edit 2: And yes, if you don't care about the esthetical differencies of your BIOSes, you can drasticly simplify this mode by adding a single regionfree bios.

 

Yes I don't understand it either. My Multi-Mega is now follow the cycle US -> EUR -> JAP, which is in contradiction with the first statement. Thanks for your help, we will try to invert cables first and if it doesn't work we'll do some reprogramming.

Also, is there someone here that tried the Mega Amp that Helder is selling onto the Multi-Mega?