Making a Megadrive\Genesis Cartridge Writer

Miles McCloud

New Member
I recently came across some Genesis "Game Factory" game cartridges(see original post Here). These are supposed to have Flash ROMS inside them, and I'm farely sure that mine are of the 32 bit variety, as they are heavy. Although I could open one up and see whats inside to be sure.

I am interesting in building a machine capable of writing ROMS to these cartridges. However I can find no info around the net on such things. Would a standard cart reader be able to write/erase data to these? I found several how-to's about building one of those. Or would I need a differant machine?

Any information would help greatly! Thanks!
 

Miles McCloud

New Member
I'll bust out a pair of tweezers right now
 

Arakon

New Member
MikeG can prolly help you, he was working on a genesis cart writer (much like his SMS one), chances are that it works very similary to these carts. plus, the carts could help him designing the flash cart for it, so you both would benefit.
 

ExCyber

Staff member
Those are too blurry to really be much of a help (using a scanner would probably provide a better picture). It's good that they're using standard flash memory, but one of those chips could be a PAL that does some CS/WE/OE multiplexing or has a write protect function. Oddly enough, it looks like there's a place for a passthrough slot...
 

Miles McCloud

New Member
I have it scanned and it turned out farely well, but my server seems to be having some trouble, so sit tight till I can get it uploaded.
 

ExCyber

Staff member
It looks like most of the connections are on the back, but from what I can see there I would guess that the two in the corner are programmable logic of some kind (most likely SPLDs such as PAL/GAL). I'm not sure what they're doing aside from decoding the high address bit (not that I can see this, but there's nothing else to do it IIRC), though ROM/SRAM selection support seems to be a particularly likely candidate.

edit: also, what looked like a place for a passthrough slot in the other pictures actually seems to be for overvoltage protection chips.

edit again: forgot to mention that those chips are definitely doing more than I mentioned above; the decoding and ROM/SRAM banking can be done with two 7400-series logic chips, which would certainly be cheaper and easier than using programmable logic, not to mention that both functions could probably fit into one PAL/GAL. I don't think it's anything on the level of the SSF2 mapper (which isn't needed in a 32Mb cart anyway), but there is almost certainly something else there.
 

Zziggy00

New Member
The Game Factory was a system Blockbuster developed to make it easier to rent video games. They made carts with Flash ROM in them - 8, 16, and 32 mbits are known to exist (I have 16 and 32 mbit carts). Supposedly, the programmer was never built in bulk like the carts were...

Sega had a bit of a problem with the idea, and by the time Blockbuster and Sega worked out any differences, the Genesis was old. A small pile of the cartridges had been built, and were consigned to oblivion in a warehouse somewhere. Apparently, in cleaning out the warehouse, at least some Game Factory carts made it to stores. Most were sold at clearance prices, but then returned because they "didn't work" (they were blank carts - no game - blue screen when turned on) - and presumably thrown away.

The carts have standard Intel flash ROM in them.
 
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