Making SEGA Genesis cartridges

[pbj]

A couple of updates.  It was time to add stereo out on the back of the Genesis 1. 

You buy a headphone extension cable for 50 cents and cut off the female end.  Then you fish the severed wire through the unused hole on the back of the case.  Still unsure what the heck that thing was for, it's on the Genesis 2 as well.  Added a zip tie for some amount of protection.



This didn't photograph so well, but the L channel wire goes to pin 1 of the Sony CXA1034 amplifier chip, the right channel to pin 8, and then you can pick up ground anywhere on the PCB.  Or pin 13 if you insist on jumping another wire onto the amplifier.  Anyway, this gets you a clean pre-amp signal almost directly off the YM2612 sound chip without interference from the headphone port.   I opted to tie into the sound chip ground pin.



Then you seal it all back up and here you go:




In other news....

Somehow my AliExpress order of "5 32X cartridges x 4" got converted into 4 cartridges.  Still got charged for 20, though!  So we're in the dispute process, but here's what I got:



It's the usual Genesis flashcart and works with the Genesis flashcart flasher, but it does have the wider 32X hole pattern.



Lesson learned here was I would be very, very careful spending any kind of real money on a 32X cartridge you can't open up and verify yourself.  The shell is dead on accurate to the real thing and the overall weight is comparable. With a high quality label, it would be very difficult to tell the difference.


 

[Malenko]

So we're gonna make a buncha spiderman Web of Fire carts?

[Manu25]

Let me introduce myself: my name is Manuel, and I'm passionate about retro hardware, especially the Sega Genesis/Mega Drive. I've been researching the creation of homebrew repros and cartridges for some time now, and I decided to join this forum because I see a very active and knowledgeable community on the subject.
I tried to create a functional Sonic Hellfire Saga with save but couldn't, and after Googling, I ended up here. I hope you can help me.
Thanks in advance.

[pbj]

Howdy, Manuel, nice to see someone interested.  I posted the art files and the PCB here:

https://forum.arcadecontrols.com/index.php/topic,164992.msg1777919.html#msg1777919

Malenko put together the nice looking art package.  One resides in the World's Largest Sonic the Hedgehog Collection outside of Houston.

That's the revised gerber file that resets the FRAM or whatever chip appropriately.  I still chuckle that nobody noticed in six years that it wasn't working correctly.  Author claimed it was fine on PAL consoles.  Bill of materials was about $12 a cart last time I made one.  That cartridge also works with a lot of the newer homebrew made with SGGK - I don't think I ever got it reliably saving with Gun Slugs, but Cave Story, Sonic Complete, and Rocket Panda were fine. 

[Manu25]

Hi friend, THANK YOU for sharing the file with us and the arts, I will convert it to PAL SEGA MEGA DRIVE.

I have a question about this. I'm trying to order the boards from jlcpcb, but I've noticed that the drills on the board don't appear in the viewer, while they appear correctly on other boards I've ordered previously. I've attached an image. Is this correct?

[pbj]

It should have holes.  I ordered mine from PCB Way and had no issues.  In fact, I uploaded the exact same file here that I uploaded there.  Make sure you solder those 322 jumpers before you populate the board or you're going to have an annoying time.


Maybe Malenko can post the PSD files so you can convert his artwork to the PAL layout?

[Manu25]

Thank you again, I ordered. I'll tell you if I can get them to work, thanks.

[Manu25]

@pbj just received the boards and all components and yeah!!! it works perfectly, thank you very much. Now i will make the pal cover, when finish I will publish it here.

[javeryh]

Earthion looks pretty awesome and is supposed to get a cart release in the near future. Thought you might be interested if you haven't seen it yet: https://www.timeextension.com/reviews/steamdeck/earthion

[pbj]

That rom is 7.5MB so it’s going to need some sort of mapper to work.  I’m very curious to see how they manage it.  Supposedly there’s $25ish bootlegs of Demons of Asteborg so I guess someone in China figured it out.

[bobbyb13]

Well, I find it all interesting but I have neither time nor brain cells to figure out what's going on!
I do like soldering stuff though so maybe there's hope.

[Manu25]

That rom is 7.5MB so it’s going to need some sort of mapper to work.  I’m very curious to see how they manage it.  Supposedly there’s $25ish bootlegs of Demons of Asteborg so I guess someone in China figured it out.

This is the pcb used for Aliexpress Earthion. I don't find info about that chip AA*

[pbj]

Mourix recently did some revisions on the open source Genesis FeRAM cartridge that can be found here:


https://github.com/soniccd123/Genesis-FeRAM-Cart

Which I think I have forked here:

https://github.com/pinballjim/Genesis-FeRAM-Cart

(the file is also attached)



Tested and fits in vintage Sega Genesis, 32X, and Electronic Arts shells.

 

Dumping the readme here as a backup:

This PCB layout has been modified to be universally compatible with Sega Genesis, 32X, and Electronic Arts cartridge shells. The file Cart_FeRAM_Holes.zip has been confirmed working with an order from PCBWay and with original shells.

All credit goes to Mourix for alteration of the existing PCB design. I simply measured holes and begged.

Original project can be found here:

https://github.com/soniccd123/Genesis-FeRAM-Cart

Unedited readme from original project is below.

Genesis FeRAM Cart
A open Sega Genesis cartridge PCB with save feature

This projects uses a 27C322 4MB EPROM Chip and a FM1808 32KB FeRAM as save storage. It was developed in KiCAD and tested in real hardware.

In the actual state, this cartridge features:

Suports Genesis and 32X software
ROM Support for up to 4MB
Save support for all ROM sizes (Selection for <2MB/4MB by jumper)
32KB of FeRAM for saving
No need for battery for saving
Rudimentary ROM bank switch (Permits multiple games on same ROM)
This project is possible thanks to TmEE (NESdev Forums, SRAM wiring schematics) and Rene Richard (db-electronics on GitHUB, KiCAD libs for the Genesis cart connector).

Component List:
U1 74HC74;
U2 FM1808B;
U3 74HC139 (or LS);
U4 27C322 (May use other 27CXX memories with some minor modifications);
R1, R2, R3, R4 1K Resistors;
SW1 4 channel DIP Switch;
C1, C2, C3 10nF Capacitors;
How to use:
Bank Switching: The user may write multiple roms to the same EPROM, the DIP switch controls which area of the EPROM is read by the Genesis/Mega Drive; The minimum bank size is 256KB. Each of the switches connect a memory address line between the system and the EPROM: when the switch is on, the respective address line is controlled by the Sega Genesis; When off, the EPROM adress line is pulled-up and cut from Genesis control. the address lines are A20, A19, A18, A17 (considering LSB as A0). To select the desired bank, turn the switches on and off acordingly to the begining address that the ROM occupies in the EPROM.

Examples:

ROM_x begin at 0x100000 -> Switch just A19 off (pull-up);
ROM_y begin at 0x180000 -> Switch A19 and A18 off;

This technique may not be compatible with save supporting Genesis software.

How to make multirom file: Just use the CMD command "copy /b rom_x.bin + rom_y.bin + rom_z.bin rom_result.bin" to join them to one file. One may join how many ROMs he wants to, just be shure that the result file is smaller than the total size of the EPROM and that the ROMs fit correctly to each desired bank to make software switching possible.

JP1 jumper: This jumper is the result of some tests with varied sized Save RAM suporting software. This jumper is necessary for software bigger or smaller than 2MB to correctly save and detect the FeRAM. For software bigger than 2M, one must connect (with solder blob, 0K resistor, etc) the >2MB part of the jumper; for smaller or equal to 2MB software, one must do the same with the <2MB part of the jumper.

Other than that, just write to your EPROM and happy playing!

[bobbyb13]

Well now THAT is damn cool.
What will be the first subject of this fancy project?

drill go brr
 

[pbj]

Doom Resurrection for 32X for my mostly platonic friend Malenko

https://www.doomworld.com/forum/topic/119202-doom-32x-resurrection/


I didn’t hate the original 32X Doom but was already quite fatigued by the game by the time I bought a brand new $20 32X just for the copy of Doom. 

Resurrection is a phenomenal improvement and he’s been begging for months.  Those surface mount FeRAM chips are gonna be… fun.

 

[bobbyb13]

My soldering skills suck and my eyesight is even worse.
Couldn't imagine being able to pull off what you manage with these.
Lookin forward to pics!