Aiwa Mega-CD Game Unit BIOS Dump [MPR-15768-T] [2.11c]

Actually, truth be told, whenever I do buy from them it's usually over their AU$40 free shipping value anyway.
You can never have enough spare components... right?

Yep, if it is anything everyone needs it is more Mega Drive 1s that look like that one above. Everything swappable, everything pluggable.

I didn't even think about desoldering some SMD electrolytic caps I did the other week. Just twist, twist, free! Did damage one board though... hmmm hindsight...

 

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I did use tweezers for poking the tiny, tiny resistors but the SMD capacitors worked better on removal by fatiguing the metal legs with pliers!
Strange way to do it, probably a high amount of risk, but meh LC 475... dime a dozen until I break them all...
Might actually increase their value! :triumphant:

 

When i did the recap on the sega cd, i used small cutters to cut the capacitor where that lip is at the bottom. The plastic base then slides off, clean the crud from around the legs and desolder the legs from there. No torn traces and no trying to desolder with the layer of crud.

 

Metal fatigue is more fun though! :wink-new:
I did see a guide on the net that cut through the metal barrel of the capacitor...
Turns out all the plastic bases were pretty much brittle anyway... they just fell apart!
Such a pleasant smell too. Reminded me of Game Gear... :dejection:

 

He means surface mount tweezers:

http://uk.farnell.com/xytronic/226/tweezer-desoldering-smd/dp/4683614

 

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They are crap anyway, I have owned a pair for years and never use them.

If you already own a soldering station - http://www.ebay.co.uk/itm/CSI-TWZR-...rden_PowerTools_SM&hash=item4ab4a79c14&_uhb=1

 

Do you want/need a region free bios made out of this ?

 

Cant have too many region free bios variants!

 

Hahaha, yes please! The more the merrier! :congratulatory:

 

I have 7 variants sitting on my Everdrive MD. Model 1 J,U,E, model 2 J,U,E, and US CDX. I had 2 more but they were no use to me and went to the garbage bin. I have no Wondermega or Laseactive.

I see no difference externally between the US CDX and US model 2 BIOS minus the revision version. Changes must be "under the hood".

 

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That's a lot of BIOS! I'll probably start hoarding BIOSes and paperwork soon too.
I mean unless anyone else out there wants to pop them into one giant zip file for me?
Damn that would be handy :victorious:

 

Here are all the ones I have at the moment:

https://mega.co.nz/#!xZxAjCra!PJOdKRVZWpVhOGW8vepx013jIJ8emzJtWaCdwMa-kAs

 

Many thanks kind sir! :encouragement: Damn that's a lot of BIOS!

 

Hahaha, what's your mind doing down there? In that gutter! :boxing: ?

 

Okay folks have fun ! Aiwa MEGA-CD bios hacked for your enjoyment:
View attachment MPR-15768_hacked.zip

It was like 5 minutes to hack it after having work in so many different BIOS ROMS ... :triumphant:

Edit:

Hack explanation:

change 1:
Sub CPU BIOS is extracted, analyzed and patched to aways success checking SEGA LOGO test without actually check it.
Cub CPU checksum is repaired and it's re-packed using Nemesis algorithm then re-inserted on the BIOS.

change 2:
Mega Drive CD BIOS is changed to not jump into region lockout warning program. Text message area is reused for part of the SEGA licence screen hack.
System BIOS subroutine at 0x0000364 is changed to jump inside of the region with the region warning message, a jump is added to a copy of SEGA licence code taken from a disc which was pasted at 0x0008900.
License code offset is loaded with the BIOS memory address range as data source then it jumps to the real SEGA licence display routine that were originally refered to at 0x0000364. Game executes after the correct logo for the BIOS is displayed.

 

Jolly good work! Thanks for doing that and thanks for the explanation too!
If only my sockets had arrived, I'd try plonking it on an EPROM and testing on the actual unit... oh wait..
That would mean I'd have to repair the actual units...
Although I was thinking, in theory I should be able to just throw some voltage at the Game Unit and it should boot up right?
Video output is on the Game Unit, all the circuitry is there too...