Making SEGA Genesis cartridges

[Mike A]

Thanks for the love.

They do look pretty sweet.

I am really happy with the way they came out.

[dmckean]

Good stuff!!

The homebrew carts are my favorite.

[PL1]

In other news, I was quietly given some PCB plans for a reproduction board that will supposedly allow a 4MB rom to save to FeRAM.  It uses a 74LS74A flip flop and a 74LS139 2x4 decoder.  I'm pretending I know what those words mean.  I went through many, many PCBs and only found those chips on EA College Football and EA NHLPA93, which are both fairly early EA sports games.  So I went ahead and ordered some more from China.  74LS138N and 74HC00N were on tons of Sega / EA / Akklaim boards but I'm too dumb to look at the datasheets and figure out if they're compatible.  I'll make one cartridge with sockets and see what works, I suppose.  The weird FeRAM chip that literally only Sonic 3 used has also been ordered in bulk.

74LS74A flip flop - A flip-flop is a circuit that comes with two stable states and is usually used to store binary data.  It works a bit like a push-on/push-off power switch where you can set/reset the current state to on or off as needed.

74LS139 2x4 decoder - When the Enable pin is at logic low, the chip uses 2 inputs (A and B) to select which one of four outputs to set to logic low.  (Y0-Y3) The chip contains two of these 2x4 decoders.

74LS138N 3x8 decoder - When the Enable pin is at logic low, the chip uses 3 inputs (A, B, and C) to select which one of the eight outputs to set to logic low.  (Y0-Y7)

74HC00N Quadruple 2-Input NAND Gates - This chip has four negated logic AND gates. If both inputs to the AND gate are logic high, the output is logic low.  If either or both input are logic low, the output is logic high.

None of these four chips have the same function or pinout.


Scott

[pbj]

So, I got my PCBs and components in and made a tester board. 



Learn from me - don't use machine pin sockets for 30 year old recycled EPROMs.  I've subsequently ordered a ZIF socket I'm going to stack on top of it.

You can also see my high tech "edge beveling machine" in the background which consists of dragging the edge of the cartridge at an angle on sandpaper.  This is to make insertion easier and less likely to damage your console.

Anyway, I've got Cave Story booting and playing on a dedicated cart for the first time ever.  It's not saving, nor is it displaying the save game icon (hovering floppy disk), which I find very odd.  I guess there's some mechanism by which it detects your ability to save.  Buried deep on the Cage Story megadrive port website, he mentions that it uses 8kB saves but that he's modded the header to say 32kB to increase compatibility with flash carts.  Well, I had, of course, ordered 8kB FeRAM 1608 chips like what I thought was used on Sonic 3.  Modifying the header back to say 8kB saves didn't change anything.  So I busted out another $20 and ordered a stack of 1808 chips.   We shall see.

This PCB was designed on a French forum and they have the Megadrive section walled off.  I've registered and begged for access but so far no dice.  I'm hopeful that with an 1808 FeRAM chip that this board suddenly becomes compatible with SGDK designed games.  What is of slight interest is that the board supports a 4MB rom and saving games.  SEGA never accomplished this in the 90s.

 

[Mike A]

This PCB was designed on a French forum and they have the Megadrive section walled off.  I've registered and begged for access but so far no dice.

So what did you do to piss them off?

[pbj]

Turns out I have to make "10 quality posts" before I can get into that section.


 

[Mike A]

You're ---fouled up beyond all recognition---.

[pbj]

You're ---fouled up beyond all recognition---.

My joke, except repeated.

 

[bobbyb13]

You can always try posting "Macron is a fascist ---uvula---!" on there somewhere 10 times and see if that works.

Of course you'll need to post that in French I imagine.

You're ---fouled up beyond all recognition---.

My joke, except repeated.

 

[pbj]

Decided life is too short so I’ve been using the Game Genie.  Batman is indeed a very good game, so good tip there.

I finally beat Mystic Defender level 4…. Because I just haaaaaaad to have the “uncensored version” it meant I was very limited on known game genie codes.  You could have near invincibility or unlimited lives but not both (lives takes all five lines on the genie).  Invincibility meant you don’t bounce back when you touch an enemy.  You fall down a pit?  Dead.  That infinite lives code?  9 lives becomes 8 when you fall down a pit.  Lava is treated like a bottomless pit.

So, with invincibility, I was able to make the jumps without having to worry about dodging enemies,  Still barely pulled it off.



Other than that level and the final boss, it’s really not that difficult a game.  Whenever I showed off my region switch on the genesis, this was my go to example.





https://tcrf.net/Mystic_Defender

[pbj]

So, here's a BYOAC World Exclusive.   



I've been badgering the Red Miso team for months and finally got one of their programmers to indulge me.  We went through..... many.... ROM revisions, but now we've got Sonic Hellfire Saga booting and saving on original hardware.  Every EPROM I own is currently being rotated through my Easy UV Bake oven this evening.

Sadly it's not saving on my French Ultimate Console boards, but it works perfectly on my arch nemesis the World Series Baseball 96 PCBs. 

So if you want to find out how much I love you, ask me to make you one. 

 

They should be releasing the new version soon.  There's some bug fixes bundled into it, too.

 

[Malenko]

So if you want to find out how much I love you, ask me to make you one. 

I cant wait till it shows up in the mail, and I love you too.

[pbj]

So, I just spent a… lot… on World Series boards and it turned out the issue with my Ultimate Console PCBs was a lack of a reset line to the 74LS74 chip.

Still working with the Hellfire people to get it saving on these French boards but now I’ve got Sonic Complete and Cave Story saving correctly.

[pbj]

So, I messaged the guy that designed the PCBs and he says he has a personal copy that’s correct and what’s posted wasn’t the latest revision.  I found it simultaneously funny and sad that nobody has noticed this mistake in 7 years.  Really drives home what a tiny niche I’m living in.

Anyway, he claims tying pin 1 of the 74LS74 to Vcc will also make it work, but that some games may require it be tied in to the VRES line found on B27 of the cartridge.  I’ve already damaged my cartridge slot with jumper wires on the edge connectors (one of my female pins is now a folded over scrap of capacitor leg), so I am really trying to avoid doing that more.  So I may revise the Gerber files to either add this line to the chip, or at least a decent solder pad for a jumper wire safely removed from the male edge connector.

That being said, there’s a million places to tap into Vcc, including pin 14 of the same 74LS74.  I’ve done that and tested Cave Story, a new Hellfire Saga revision, and Sonic Complete.  All three saving correctly.  The poor Hellfire saga programmer is learning that the true hellfire was all the UV light I erased those EPROMs over and over in again along the way.  They should be releasing what I like to call the “shut pbj the ---fudgesicle--- up” revision publicly soon.

What this means is that the… let’s call it… sure… $50.. yeah… just $50 I blew on more copies of World Series Baseball 95 and 96 this weekend wasn’t needed.  And I also don’t have to desolder 84 pins unless I really want to. 

But it also means I can make these from entirely new boards and components and no longer have to kill old games.

So here’s your first look at an entirely new (okay the eprom is 25 years old) Hellfire Saga.  This has been fun and I’ve come a long, long way…

 

[bobbyb13]

100% awesome.

Makes me want to buy a Genesis and support your fledgling business.

How much ya gonna charge per cart to recoup development costs on your (ahem...) what, $100 now total in otherwise old neglected pcb carcasses?!

[Malenko]

He's in for way more than that, cause he spent more than I have and Ive spent a couple hundred.

[pbj]

I’m probably in two grand but I’ve been at this about 18 months.  EPROM prices have gone insane but I don’t think I’m quite ready for surface mount rom chips.  Give it six months and I’ll revisit that.

But cracking the issue with this Ultimate Console PCB has opened up a whole new world of modern homebrew games.  Hellfire Saga is actually quite good now that I’m allowing myself to play it beyond save testing.

Here’s Malenkos art package on regular paper tacked with a glue stick.  Photo paper and glossy labels coming soon.

 

[bobbyb13]

I figured you were into it for a few bucks.
This video game hobby thing is a slippery slope on all fronts.
It's alarming how much worse pinball is. 
For a year and a half of product R&D that isn't that bad!

Love the story of this game coming together as it has.
Although we weren't playing it on a Sega system my son Tyler was already kicking ---my bottom--- at every Sonic game we had by the time he was 7.  Maybe even 6.
I haven't played any since as I've been distracted with these big ass wood boxes for so long now.

I wonder if he is even aware of the Hellfire Saga at this point.

Nice work gents.  That is some legit lookin stuff.
 

[pbj]

Photo paper arrived, so I figured I'd share an old trick I like to call... uh.... how to get a 10.59" wide image printed onto letter paper.  Your printer can do it but it will gripe at you.

Create a document that's legal size.

Set your leading edge left margin to 0.2".  Ignore any and all warnings.  Insert your 10.59" image aligned to the left margin.

Cut a 3" wide strip of paper.  Overlapping as little as possible, tape it to the right edge of the page.  You've got very little margin for error here.




And here's more or less the final product.  Someone buy one, plz. 

[bobbyb13]

Love it.
I'll support this habit.
How much $$ do I send where/how?

[pbj]

You can’t get just one game.     

Materials cost on this one… I’ll have to add that sad number up. 

Have you picked up a Genesis console yet?

[bobbyb13]

Agreed on games!
I need to pick up a console still.
I have seen a few second hand ones in stores here so it may not be so difficult to get a functional one.
Any recommendations on generation to shoot for?
I've noticed that the serial numbers begin with a letter.

I am nearly finished with a scart rgb modded Sony TV at this point but I don't know what video connection any particular Genesis uses- and what I find here may be a built for (not just in) Japan version.

How slippery the slope.

You can’t get just one game.     

Materials cost on this one… I’ll have to add that sad number up. 

Have you picked up a Genesis console yet?

[pbj]

Genesis 1 or 2.  Both output native RGB and you can get SCART cables.  Avoid Genesis 3.

They also make HDMI clones.   

 

[pbj]

Took matters into my own hands with a cordless drill!  And now we’re running primo homebrew in EA shells.

 



Ordered some more of these PCBs but went blue mask this time.



I’m low on SEGA shells, I’ve got plenty of EA.  I did the math.  SEGA carts running me about $8, EA about $7.  Haven’t gotten my hands on a big cart lot in awhile, so I may have to start ordering repro shells.   

[pbj]

Guess who just bought a box full of complete copies of NFL 94 starring Joe Montana.   

Losing access to the laser printer has kind of sucked.  I was getting very sharp and vivid labels.  The downside was the image was matte and if you peeled back and reapplied the sticker, the image was pretty much ruined.  I guess the inkjet stains the paper, so they're very tolerant of adjustments, but if you have a sweaty thumb or something you're going to smear the art.

So I've been playing around with AquaNet.  You can spray it indoors, it dries quickly, it adds a nice 70s vibe to your workbench.  Even with very misty, light coats, it causes the ink to bleed and soak into the paper a little bit.  Makes it surprisingly resistant to moisture, though.

Went back to Minwax Polycrylic polyurethane clear coat.  Two very light coats and you don't get any image changes, but now you've got a leathery texture.  Short of the back of the sticker getting soaked, moisture isn't going to do anything to the image.

Didn't photograph so well, but here's a side by side.



Clearcoat on the left labels, AquaNet on the right.  Spray painting mailing labels.  This is what my life has become.

 

EDIT: Here's a better pic.  AquaNet on the left, clearcoat on the right.

[pbj]

 

[bobbyb13]

Well ---steaming pile of meadow muffin----
I've used AquaNet to put bicycle handlebar grips on for decades.
Nice and slick when first shot, stupid sticky afterwards.
Funny because a brilliant half-mad and very lovable guy from NYC I was lucky to know taught me it's usefulness in that manner.
Also easy to experiment with as my mom had a pink can of that ---steaming pile of meadow muffin--- in the bathroom ever since I could remember.
Now I do too. 

NEVER would have considered its potential usefulness as an ink sealer.
Solvents are interesting things when aerated, and may be the differeence between the ink jet and laser prints actually.

I know from fiberglassing stuff that if you use oil based colors with styrene they bleed like f'n crazy.
All the paint used is water based so it isn't solublized with wet resin.

Curious to know how this works with your label testing.

And I still want to buy some carts.
 

[pbj]

I’ve been slowly reprinting all my AquaNet era labels and redoing them with clearcoat.  HP sent me a third cartridge.   

Anyway, fixing to mess up Joe Montana….  Revised PCBs arrived from China.  Sonic blue this time.

[Mike A]

Has someone designed a 3d printed shell?

I have a 3D printer that actually works.

I have no 3D design experience so I need a model, but I can hit the print button on my machine.

[pbj]

For storage there are these...

https://www.thingiverse.com/thing:766810

 

[pbj]

One of the new boards populated.  These things take me almost an hour to assemble and test.

 





And here’s the “final product.”  Nearly $20 each in materials cost.   

[Zebidee]

Maybe you could try doing the ICs with solder paste (apply from a syringe) and hot air. Applying lines of solder paste along those rows of pins would be easy, and then you blast it with (temperature controlled) hot air. Takes a little practice to work out how much paste to put on etc., The solder naturally tends to clump onto the pins anyway. Easier than soldering each individual pin anyway.

I use a "JCD 858D", which is a clone of some other brand. It was cheap (like ~US$50-70 or so) but it works well, allowing you precise control of both temperature and fan speed. I use it for all my SMD stuff in particular, but keep finding more uses. Love it for heat shrink tubing, I cringe when I see people using cigarette lighters.

I just googled " 858D" and got clone hits on ebay for under $10! Not sure I'd trust them. Described as a "Hair Dryer Welding Tool". FFS, don't use these things to dry your hair! You'll have a bad-hair day.

https://www.ebay.com.au/itm/265812816698?chn=ps&_ul=AU&_trkparms=ispr%3D1&amdata=enc%3A1Y-f6aMXgQYOW1HBTRQKmgg65&norover=1&mkevt=1&mkrid=705-139619-5960-0&mkcid=2&mkscid=101&itemid=265812816698&targetid=1598469862718&device=c&mktype=pla&googleloc=1000286&poi=&campaignid=19657035767&mkgroupid=143201283022&rlsatarget=pla-1598469862718&abcId=9305369&merchantid=614912741&gclid=CjwKCAjw1MajBhAcEiwAagW9Ma-cOSS-FDzE67-t3I1K6-mbPjsbU1ZPDJ4anxE51SumG-CV98f0zhoCBocQAvD_BwE

[bulldawg]

I have a ton of 32pin m27c400 chips is there anyway to use them instead of 40pin m27c400?

[pbj]

Probably.  Do you have a datasheet?

[pbj]

[bulldawg]

Probably.  Do you have a datasheet?

No I don't.

[pbj]

I think I found it.  It looks like it would work but you'd have to make some kind of adapter to reroute the pins.  The 27C160s are about 75-80 cents each in bulk, so I'll let you make that determination as to "is it worth it."

 

[pbj]

Off topic, but this is where I ramble anyway so I'll post it here. 

I got tired of fighting my Retro Duo, which is a clone NES/SNES.  When it works, it works, but I've had to open it and reinforce the PCBs, replace most of the internal wiring, reflow the power jack.  Just on and on.  Recently I was thinking, "remember when Zelda games were actually fun and you weren't boiling mushrooms and slugs all day?" and tried to play Link to the Past.

Well, $30 and 72 hours later, I had a Super Famicom in hand.  99% of my SNES gaming is off an Everdrive clone in a universal shell, so it didn't really matter to me.  However, I do have about six or so original games that I bought in the 90s and I like to play them occasionally.  I'm not really a fan of shell mods... this system made it a good 30 years before I got my hands on it, I'm not widening the cartridge slot.

Other option is to play the games as loose PCBs.  No.

Another option is an adapter.  They're $20 on Amazon but they're really meant to make Super Famicom games work on SNES for people too squeamish to snap off two hidden plastic pegs.  They'll work the other way, but you've got to chop up or remove the shell it's in.  Why they didn't make a universal design is beyond me.

Another option is to use a Game Genie I already had.  Again, you have to strip it loose or cut the shell to hell and back.  But I popped out the board and took a look at it.  Held it up to a Super Famicom shell.

$4.60 and 4 days later, some random crap game was delivered in a huge box on Memorial Day from Japan.

With enough cutting of the internals of the shell, using the soldering iron to burn away enough of the top to get the slot exposed... the damn thing actually fits.  (Again, why didn't they use a universal shell??)



Then it turns out the Revision 1 Game Genies do not work with hi-rom games.  Game will boot and immediately freeze.  The solution is to remove 6 470 Ohm resistors and replace them with 100 Ohm per some NESDEV thread.  I had 4 100 ohms, 1 120 ohm, and 3 of the 470s were twisted together in parallel to make ~150 ohms.  Close enough.





 

[lilshawn]

thats hilarious, i do the opposite... i use my game genie to plug in curved SFC games to my square ass console. i could mod it to take them, but i'm lazy

[bulldawg]

I think I found it.  It looks like it would work but you'd have to make some kind of adapter to reroute the pins.  The 27C160s are about 75-80 cents each in bulk, so I'll let you make that determination as to "is it worth it."

 

Thanks for the help, Yeah I believe it to be easier to just get the right ones. Do you have a suggestion on where to buy or is ebay the best option?