Making SEGA Genesis cartridges

[pbj]

Yep, remove those chips above your eprom and then add jumper wires that will reconnect your chip legs to the appropriate pin on the edge connector.  Look for traces that come off your eprom and go up to the chips and don’t have a direct connection going down.  Looks like maybe pin 9 off the eprom?

[bulldawg]

Is it because those are sram?

[pbj]

You put a non saving game on a saving PCB.  That means when the game is trying to load a certain part of the rom, it’s accessing those save game chips instead.  You need to remove or disable the chips and make a direct connection from the eprom to the edge connector.

[bulldawg]

Well I had read that the hack had a built-in feature to use SRAM to save the high scores but apparently it's not compatible.

[bulldawg]

You put a non saving game on a saving PCB.  That means when the game is trying to load a certain part of the rom, it’s accessing those save game chips instead.  You need to remove or disable the chips and make a direct connection from the eprom to the edge connector.

From what I can tell by removing those two chips it doesn't interrupt the path from the eprom to the edge connector. Or I may be misunderstanding.

[bulldawg]

Removing the two chips worked, did not have to add jumpers. Thanks

[pbj]

So, I took a deeper look at Quarterback Club 96 vs Mortal Kombat Arcade Edition.  I had no idea that there was a single chip 4MB ROM game with saving, and that could actually be a useful PCB for Phantasy Star 4, Beyond Oasis, and some of the new homebrew like Cave Story.  I don't think I've had one of those PCBs come across my desk, but I'll definitely take a closer look.

Anyway, here's how the two headers compare:



Notice that the ROM End address is total nonsense on MK, instead of RA it's got ||, and 5421 instead of E840.  It also points to a non-standard SRAM start and end address.  I've contacted the patch creator about some of his other SRAM patches, most recently his Ghostbusters one, and he and I have a difference of opinion on what "tested on actual hardware" means.  He's playing these on Everdrives, and the layer of emulation those have ignore these mistakes and work anyway, but none of this will work on an actual cartridge.  Even going in and manually correcting this won't make it work, so in short I have never gotten a single one of his SRAM patches to work on actual cartridges. (and I've tried many of them)  He did release a revision of Ghostbusters that fixes some of the header junk.  Still doesn't save on a real cartridge.

 

[bulldawg]

Fyi College Slam is the same way.

[pbj]

Well, all those 4MB Akklaim boards are also ones where you can just simply pry off the ROM, so I actually had about a dozen of them stripped and ready to go.

I gave it a couple of tests with Cave Story.  Once with no modification to the header, and a second attempt where the header had been modified to match Big Hurt on the SRAM start and end spaces.

Anyway, booted fine with both setups but would not save on either.  I like Cave Story as a test because it's fairly tolerant and you know within moments if saving will work or not.  So unless the game is programmed to use EEPROM, I'm doubtful it's going to work.


I've attached the document from the Everdrive website that discusses all the different EEPROMs.  Really the only thing of interest is that Sports Talk Baseball can be directly converted to Wonder Boy in Monster World.

(and College Slam is actually a decent game)

[pbj]

I really need to clean up the first post on this thread and edit it to have all the useful information.

Anyway, this is mostly for my self reference, but here's how to use those old SEGA boards with the chips popped off.  This time with cleaner jumper wires.  The only thing happening on the back is I've cut the line from pin 42 of the EPROM to 5V.  Pac-Mania is a tiny ROM, so I'm pulling the 2MB pin to ground (wouldn't boot otherwise...).  Punisher and Robert Cop 2 are both 2MB, so I jump that pin to a trace running to the 2MB pin on the cartridge connector.

[pbj]

Above games with appropriate labels.






This is actually a borderline good game. Apparently it was an internet meme I missed.






I haven’t figured out how to rewire this particular pcb, but I don’t think it will be difficult.  I find this chip prying to be endlessly amusing.





Anyway, I’ve recently gotten some “really good deals” on cartridge lots but I have to pull the plug on this at some point.  If you want a Genesis cartridge… fairly soon is the time.


 

[Malenko]

great work as always. I still think I missed my calling as  a bootleg/repro artist.

[bulldawg]

So I have tried 2 eproms with Sonic Hellfire saga and neither work. Both show license screen then black. I have tested both with my test cart. The first one I read it and it was a bad write because the data was all messed up. Then second had a good read but still no go.

[pbj]

The public release doesn’t work.  I have a revision.  Did I email it to you already??

[bulldawg]

No that was tmnt.

[bulldawg]

Also does anyone have a dump of Frog Feast for the Genesis?

[pbj]

Sent you the revision.  I don’t have Frog Feast.

 

[bulldawg]

Thanks.

[pbj]

So here's an intro in the next stage of this lunacy...

Picked this up for $15 QMK LQQK mint and CIB



Problem is that Sega used the physical cartridge shape as a region lockout.  I had hoped that Sega would have given up on that given this was a custom shell, but there's that damned Megadrive notch. 



They also used a software region lock on this.  Thanks, Sega. (note to some of you - see that I am wearing both pants and a shirt in that reflection, this is how it should be done)

A simple Game Genie code (RYBA-E61G) will bypass both the physical size issue and software lock, but where's the fun in that



Step 1 is a mod I first did back in the 90s.  This time I routed the region switch out of the back of the unit.  There's already a perfectly sized hole for my toggle switch.  Genesis Model 1 also has this hole... maybe from the molding process?  Whatever, it fits.





I opted to cut a trace and scrap off some solder mask rather than lift a leg on that chip.  All the mod does is toggle between grounding that pin out (Japan) or pulling it to 5V (USA).  There's no need for PAL support in my life so I didn't bother with that mod.

That takes care of the region lock, now you have to make the genesis slot a rectangular shaped hole.

So, you get PL1 to print you some replacement cartridge slot doors.  Then you take a dremel cutting wheel to it, and then you realize the spinning shaft is etching your case, so you go back to old reliable of using your soldering iron to rough cut the plastic, a sharp pocket knife to whittle it, and then a file.  Not perfect but actually fairly pleased with this:



Looks even better with a cartridge stuck in there:




So, there's obviously no point in stopping here so I've got some Megadrive shells in the mail.  I'm sure I could get a cardboard box full of games in Japan for nothing but they're actually fairly expensive on Ebay.  Since the PCBs are the same, I figure I'll just burn the ROMs myself.

 

[pbj]

I mean… might as well lean into it.  My megadrive shells arrived yesterday.

I’m still working out the art template with ginger bae but we’re getting close.  This game may actually be the best graphics I’ve seen on Genesis.



Standard genesis shell in back for comparison.

[pbj]

I had some more pcbs printed up.  If you want one, chime in soon.  I think I have 30ish 2MB EPROMs laying around and this project is done

[Malenko]

I think I need to buy the JAP version of Virtua Racing.

[bulldawg]

Started working on this again.

[bulldawg]

I had some more pcbs printed up.  If you want one, chime in soon.  I think I have 30ish 2MB EPROMs laying around and this project is done




Have you tried to use the surface mount flash chips on these boards? Also have you ever tried doing a 6mb cart?

[pbj]

Okay, dammit, I watched some YouTube video about “Genesis games nobody ever talks about” and got dragged back in for a few more.  These are both interesting games and I had access to glossy labels, a color laser printer, and “gloss print” mode.  The end result was so good it makes me want to redo them all but that would almost as crazy as spending $2,000 remaking genesis bootlegs you can run off a $20 flashcart.



The labels have the slightly translucent look of the originals.  Dragging a fingernail across some test prints was okay, but if you flex the sticker you’ll get crackling.  Not quite sure how SEGA did it, but these are as close as I’ve gotten so far.

 

[pbj]

Another last gasp.  Retro Bit is making “big six” controllers.  These are the old three button shell with the six button dpad and buttons.  It’s messing with my muscle memory but I did okay on Super SF2.  10 foot cord, working with both my actual console and my Retro Trio 3+.A very nice product for $16 shipped.

[mourix]

This is one of the most entertaining projects I've seen here in years.

I'm only 25 EPROMs into my Mega-Tech bootleg effort but love this perfect (almost) trainwreck

[meltedcactus86]

This is awesome! I did a similar project for my SNES. I swapped all my NA cart guts to SFC carts and redesigned the front and rear labels.

https://www.reddit.com/r/retrogaming/comments/1br3a2e/custom_snes_labels/?utm_source=share&utm_medium=web3x&utm_name=web3xcss&utm_term=1&utm_content=share_button

[pbj]

Hey, those look great, nice work.  Where are you sourcing the cases?

I’ve picked up a few Super Famicom carts lately because they’re so ridiculously cheap.  So cheap, relative to American carts, that I’ve contemplated popping the chips off the boards and burning US ROMs.  Particularly the Final Fantasy games that are $5 vs $50.