View Full Version : Sega Genesis is networkable out of the box

August 7th, 2008, 08:53 AM
As per 1993 standards, it's internet ready! On some of the first models (Mega Drive, or MD) there was a port EXT on the back, and it was never used for anything, but Sega released a modem for it in Japan. It was never used here, I can only guess why. But they never explored its capabilities here for distance gaming. I'm wondering why Modem Wars never got ported to it.

On the next model, known as Model 2 by most, the second controller port is that port, serves double duty. I'm still researching it, but I think I have read so far that all you have to do is have the sega modem, but again as far as I understand it, if you put your own circuitry in between the modem and the Genesis (perhaps just resistors in a cable) you can use any modem.

Right now, you can use the EXT port with a homebuilt cable to hook up to a PC's parallel port and dump roms, and do debugging on programs.

I have all the parts, so I am going to persue this as a main project. I have a few short term goals that I want to achieve:

1. MD-MD communication with a crossover cable, model 1 and a model 2 (unless I can get another model 1)

2. MD-PC via serial port

3. MD-MD via two modems

4. Model 2-Model 2 via a crossover cable.

The only hardware I would need to buy is a rom card that I can rewrite to, and they are for sale already.

Something that cannot be bought is the program that has a 2-4 player capability through a network. I'm still researching it, someone out there somewhere has to have thought about this already. Else I will break out the 68K books again and start studying how to convert it over to the Genesis.

I've mentioned this over on threads at atariage and the sega-16 forum, and networking is also a computer function, and this thing can function like an Atari ST (at least in my mind, same processor and can probably run a small unix). So I'm bringing the idea here as well. The more people say it cannot be done or is not a worthy project (see below) the more I want to do it. GRR!




August 7th, 2008, 09:52 AM
X-Band was used in the US.

August 9th, 2008, 12:22 AM
Yes, read that too, but it seemed to not really catch on. The machine uses a 68K processor, so any help on programming for it would be appreciated. I have a few books on the Atari ST, but it's a kind of far cry from the Genesis. I think some of it may be adapted over though.

So if anyone knows of a Basic or other not too difficult language that can be used for the Genesis rig (I am elevating it to 'rig' status, :) ) let me know!

I'm in touch with Brandon from superfighter, maker of Beggar Prince, RPG for the genesis, and am getting as much input as possible from him. The EXT port and any network capabilities seem to be largely unexplored, though. I say, why waste it and not use it?


August 10th, 2008, 07:50 PM
Been gathering parts, and have plenty of pins and bulk cable to work with. I think the next thing I will have to actually buy would be a flash cart of some kind to write a game to. I wanted to use some kidn of unix, but it would take more time to port something over than hack a game.

Also, any help in the programming language would help. I am in touch with Brandon (he knows a lot) from superfighter, and have a second Model 1 on the way so I won't have to guess about the circuits behind the port 2 on the Model 2.

So that's where I am on the project.

Mike Chambers
August 12th, 2008, 09:47 AM
beautiful! i assume you could take a serial cable and rig something up to use your broadband, too. make the sega think it's a modem somehow. maybe just a null modem with a gender changer would work??

oh, to IRC from my model 1 genesis!

/me does things that are inappropriate to tell on a family-rated forum. :o

August 12th, 2008, 04:52 PM
Broadband is the plan. There are four bi-directional lines in the port, and I see no reason some kind of converter couldn't be made. A regular rs232 hookup wouldn't work, an neither would a normal serial modem, unfortunately. The port is like a really cut-down parallel port and less like a serial port. Here are the two long threads where I have been discussing it:



There has been a lot of development, and strangely the EXT port has been ignored. The main focus has been on gaming and making a new game or expanding the console. All good things to do, but not much at all as far as networking.

When I get something hard made, I'll let everyone know how to do it.

What I am trying to do now is make two consoles talk directly, that will be a first step. There's even a BASIC for programing the Genesis, and that's extremely good news. I don't have to learn its version of C to make a program that'll do something!

As far as the programming goes, I stil have to buy a flash cart for it with reprogrammable innards. The cable looks fairly straight forward, a straight cable with pin 5 not connected (+5vdc for devices). Also, since it's more like a parallel port, a parallel to ethernet may be the way to go to get hooked up online. But there are many things to be written first:

a program to use the TCP/IP protocol, use the port and send/receive data; I am also thinking embedded ethernet for this, as the 68000 processor would be hard pressed to do the ethernet work asn run a game or program at the same time. If a parallel-serial solution proves to be the best thing, then any kind of configuration may be able to be done a tthe other end, or from a server. But I am getting ahead of myself. Main thing now is to get the hardware for it and make the two consoles talk directly which should not be extremely hard.

link to the BASIC fo rthe Genesis/MegaDrive:


picture of AT&T Edge that never happened:


October 17th, 2009, 04:54 PM
Has it been that long since I posted all this??? Okay, bump for an old thread, more peopel are coming on-boad with the idea. The thread is here:


It's still a very great idea. Also, the Genesis has been gettign a lot of love lately, with two new handhelds out and coming soon with two new consoles. And TecToy has been busy as well, with the Mega Drive 4 (it has a guitar, that's cool, I might be able to AFFORD some of this new stuff now).


Even though it's been over a year since I posted, the idea is still firmly in my head, but there is little time/money to make much happen.

October 17th, 2009, 05:30 PM
Has there been any progress?

October 17th, 2009, 07:48 PM
Sadly, not by me. Life has taken over and I have to do things to pay bills before any personal projects. But the guys at sega-16 are starting to get interested. Hopefully they'll have more luck and time than I did.

October 17th, 2009, 11:27 PM
As far as porting a Unix, wasn't one of the big downsides of the 68000 that it had no recovery for a page fault or something so it was impossible to have virtual memory? (Not to mention the Genny only has 64K anyway, unless you expand RAM onto the cart port.)

Also, if you wanted to flash on a Genny, order from Tototek (http://www.tototek.com/store/index.php?main_page=product_info&products_id=59&zenid=985323e49f58dbf0b889a50f419bf099); I have a couple of their carts, they work fine, though you need a parallel port and Win9x/NT. (Never tried with a USB parallel port, though using one might make the programmer pseudo-USB.)

I realize this is pretty much a dead thread, but it would be kind of interesting to see a Genny-computer.

December 4th, 2009, 12:07 AM
Very nifty ideas! I'm already buried under current projects, but I'll put this in the queue--maybe next spring.

I've done some assembly laguage programming on the Genesis, but only for a short while, a long time ago.

As to the suitability of the 68K for Unix, I would point out that many, many Unix systems were 68K based. Including the HP9000/300 and 400 series, the Masscomps, the Amiga 3000/UX, Mac with A/UX, etc., etc. RAM and mass storage are what's needed. And if not Unix, how about CP/M-68K?

Personally, some multisystem multiplayer games would be enough for me without an OS. If the networking can be tapped, to me the next step would be networked games for 32X!



December 4th, 2009, 06:40 AM
Heck yeah, that's the way to think about it! Make the 32X and SCD have network games.

I don't have much time to work on it right now, either, but am trying to pass the idea along to friends that do.

On the Unix OS, I knew that there were plenty of ports of it out there and that the 68K was no stranger but just couldn't do the porting work myself. There has been one person on a forum somewhere out there that says they upgrded their Genesis to xMB of ram, upgraded the processor and added keyboard capability AND said that they'd never release anything for it because noone would pay him for it.

Sounds great, but then since it would never see the light of day, I have to think it's a bunch of bragging and smokeware.

I'm due to go to school soon, not too much time in class, so I will have some time to dedicate to the project. Gonna take somoe programming (I wish they still taught C).

Bruce Tomlin
January 5th, 2010, 04:55 PM
For what it's worth, all three ports on the Genesis are identical, aside from the gender of the rear port. They all have a serial interface that can do 300, 600, 1200, and 4800 baud, with interrupt support, but they can can also run in a parallel mode using up to seven bi-directional TTL-level I/O wires, with interrupt support on one of them. The latter is what Zero Tolerance (http://en.wikipedia.org/wiki/Zero_Tolerance_(video_game)) used for its link cable. The Miracle Piano used an NES-style serial interface by bit-banging.

There are many board revisions of the model 1 Genesis, which could be identified through the cartridge port if someone took the time to compile a list of the identifying marks. In general, though:

1 - Original with EXT port and no TMSS lockout
2 - EXT port still present and TMSS lockout added
3 - EXT port traces on mainboard, but no hardware or case holes
4 - EXT port traces removed from mainboard.

The first of these is probably the least common variation in the US. I had a hard time finding one at first (for dev work with a game copier, it is desirable to not have the two-second delay), but I still would not be surprised if they were about as common as the second.

As far as porting a Unix, wasn't one of the big downsides of the 68000 that it had no recovery for a page fault or something so it was impossible to have virtual memory? (Not to mention the Genny only has 64K anyway, unless you expand RAM onto the cart port.)

I think it did have something to do with recovering from page faults. Something like an instruction not being restartable under certain circumstances. I heard that the Apollo computer used dual 68000s running in parallel, and when one hit a page fault, it would start over again on the other. There was also the MOVE from SR instruction, which was non-privileged, so you couldn't make a proper VM. Both of these were fixed in the 68010.