build a Genesis

[blackevilweredragon]

I have received 4 important chips in the Genesis, all working, and I want to build my own Genesis (clone)...

I got THE Motorolla 68K CPU used in the Genesis (the one that will play ALL games), a Z80 CPU (that matches spec with the one used in the Genesis), a YM2612, and that TI noise generator...

I am highly good with building circuits, and wanted to know, is there any place online that I can find exactly how the Genesis works?  From there, I can put this thing together..  (will add RAM, and a ROM chip of course)

[NFG]

You might want to consider adding some other stuff, like, oh I dunno, a video chip.  Perhaps a video encoder as well.  There are several large custom chips in a genesis - you could probably assume in safety that they're doing something.

[kendrick]

The components you describe are pretty well documented. Sega liked using off-the-shelf components whenever possible, as it provided them with an opportunity to establish relationships with those chip manufacturers. However, the Megadrive/Genesis has some functions that are not quite so well understood. In particular, I can see the controller decoders and the Master System backward compatibility giving you trouble. I can see it taking months to get just those two functions working right.

Can I ask, what's the benefit to manufacturing your own clone? With the Genesis 3 unit, Sega and Majesco reduced all the core functions down to one or two chips already, and the Radika units are easily hacked to use a cartridge slot. I don't have a problem with what your stated goal is, but I don't think building your own hardware from the ground up is the best way to produce working Genesis hardware.

-KKC, who has conquered his Tivo.

[blackevilweredragon]

You might want to consider adding some other stuff, like, oh I dunno, a video chip.  Perhaps a video encoder as well.  There are several large custom chips in a genesis - you could probably assume in safety that they're doing something.

yea, i figured i would need the VDP also (i wrote the original post kinda half asleep)..

as for all the custom chips, that's the thing, i want to reverse engineer them, but i'd have to find out what they do though first..

EDIT:  Accidentally called the VDP a PPU..

[blackevilweredragon]

The components you describe are pretty well documented. Sega liked using off-the-shelf components whenever possible, as it provided them with an opportunity to establish relationships with those chip manufacturers. However, the Megadrive/Genesis has some functions that are not quite so well understood. In particular, I can see the controller decoders and the Master System backward compatibility giving you trouble. I can see it taking months to get just those two functions working right.

Can I ask, what's the benefit to manufacturing your own clone? With the Genesis 3 unit, Sega and Majesco reduced all the core functions down to one or two chips already, and the Radika units are easily hacked to use a cartridge slot. I don't have a problem with what your stated goal is, but I don't think building your own hardware from the ground up is the best way to produce working Genesis hardware.

-KKC, who has conquered his Tivo.

Mainly, I just wanted to do it for a learning experience.

[atom]

Last year googling around I found a website that was selling a full schematic for the Genesis. I imagine this could be very helpful in your quest. Good luck with your project.

[blackevilweredragon]

After some help with some electronic friends, and help from a local PCB factory, I finally built a Genesis clone..

HOWEVER:  There's a glitch..  the music plays to fast, DAC channel slightly distorted, graphics are corrupted, laggy, and very slow (on sonic 2, im only getting about 20fps, with some hint of 50fps)...

I have NO idea what's going on...

EDIT:  Forgot to mention, the graphics are also "tearing" too...

[Scias]

I was really interested to see how this would turn out back in the summer.  Even if it doesn't work right, it was still a pretty ambitious project.  Good job!  (post some pics after you get it finished)

[blackevilweredragon]

I was really interested to see how this would turn out back in the summer.  Even if it doesn't work right, it was still a pretty ambitious project.  Good job!  (post some pics after you get it finished)

i will try and get pics when the thing actually looks good..  right now it's booted by atleast 20 jumper wires (due to design flaws)..

and im thinking something is wrong in the CPU area (from what I can tell, that CAN cause bad DAC quality)..  (i never did test the hardware, but was told they were good..)

[blackevilweredragon]

here's something I can't figure out..  It's VERY off in it's coloring...



me and the other guys are ready to call it quits on this project..  we just can't get it working (we hardly could get it to boot)

[viletim!]

You cloned a Sega Genesis? Really? You actualy built one without using any bits from an original console?

[blackevilweredragon]

You cloned a Sega Genesis? Really? You actualy built one without using any bits from an original console?

yea, from off the shelf components, along with chips from a real genesis, that you can't get off the shelf..

[bumpytrot]

we're lacking specifics here. i see you're able to take pics, so let's see where you're at so far with the system itself. thanks!

[blackevilweredragon]

we're lacking specifics here. i see you're able to take pics, so let's see where you're at so far with the system itself. thanks!

i will try to remember when i get home..  my fathers got the camera, so when i get it back, ill try to remember...

[RobIvy64]

Bump! Any pics of the board you built? You are a secretive individual when it comes to pictures.

[blackevilweredragon]

this project has been long scrapped..  it never worked right, i could never get the picture doing it's job...

[kendrick]

I still think it's worth documenting what you did. When most people in our club try their hand at emulation, it's generally a software-only affair on another platform. Apart from the Asian toy companies, very few individuals attempt hardware emulation with any success. This is discounting the OEM TurboExpress, which has to run some additional firmware on top of the two 6520 chips to completely emulate the functions of the HU6820 chip.

Upon reflection, I would like to see hardware emulation become the standard rather than the exception, as it's independent of the platform. I don't imagine that every Tom, Dick and Ahmed will be able to whittle an NES out of wood, but I do think working hardware has a quality that isn't matched with software-only emulation.

-KKC

[blackevilweredragon]

well, i didn't really document things, one of the main problems i had a problem with the project, but i will try and explain what was used..

I used a standard M68k and Z80, used VDP, and glue chip from a Genesis..  i also used a YM2612 chip...  (funny, i almost used a 3812..)

i then put it together how I saw fit, and assembled it into an old AT PC case..  I use the NTSC encoder from a dead model 1 Genesis..  (actually an MD)

I used regular PC male DB-9 ports for controller ports, and it did NOT have an EXT port..

mine did have a VGA port on it, with a built in sync separator..  but i couldn't even get THAT working, cause at the time, i didn't even remember my LCD could handle it (which makes me disapointed i ever killed the project)

[RobIvy64]

i will try to remember when i get home..  my fathers got the camera, so when i get it back, ill try to remember...

hhmmmm


i'd have to see this to believe it.

EDIT: God if Epicenter finds this thread... :rolleyes:  

[blackevilweredragon]

when i said scrapped, i meant scrapped...  it's no longer in ONE piece..

and geez, i don't see what's so hard to believe..  all you have to do is follow the schematics..  it's pretty much a genesis model 1 clone, with some other parts on the board...

[NFG]

What's hard to believe is that anyone would take a handful of chips with the several hundred inter-chip wires that would be required and attempt the idea at all, it's a mind-boggling amount of work, even if you etched your own PCB instead of soldering wires all over the place.

[NeWmAn]

the OEM TurboExpress, which has to run some additional firmware on top of the two 6520 chips to completely emulate the functions of the HU6820 chip.

Hi,
Can you explain what is the "OEM TurboExpress"?  

[RobIvy64]

the OEM TurboExpress, which has to run some additional firmware on top of the two 6520 chips to completely emulate the functions of the HU6820 chip.

Hi,
Can you explain what is the "OEM TurboExpress"?

He's referring to a portable Turbo Grafx 16.

[NeWmAn]

I know what is a Turboexpress, I wanted to know what he meant with the thing about the emulated Hu6280.

[NFG]

Every TE I ever opened had the exact same 3 chip setup as all the other PCE/TG hardware.  And what the hell's an OEM TE?  No other company ever rebadged the system, nor was it ever included in any other manufacturer's bundles, which are more or less the only ways I've ever seen 'OEM' stuff used.

(And yes, I know what OEM means: Original Equipment Manufacturer.  The question isn't 'what's OEM' it's 'what the hell?')

[kendrick]

Bad choice of words. I was making it clear that I was talking about the manufactured TurboExpress, as opposed to one that might have been assembled by a hobbyist the way Dragon did with his Genesis. To my knowledge, this has never actually happened.

-KKC

[GZeus]

He also apparantly 'built' and 'coded' a setup that ran MacOS on a Genesis/CD/32X setup.
This was more believeable.
Hell, I bought this.

I mean, I read it after I'd read that LOONG article carefully detailing the process of making an FPGA PC Engine clone.

This is more physically problematic(more wires, resistors etc) but less mentally stressful.

Thing is, without the ability to use tiny mchine soldered resistors/caps etc this would be the size of a damned table if it was done right.

Is it possible he did this? Yes.
Is it likely? No.

[RobIvy64]

He also apparantly 'built' and 'coded' a setup that ran MacOS on a Genesis/CD/32X setup.
This was more believeable.
Hell, I bought this.

I mean, I read it after I'd read that LOONG article carefully detailing the process of making an FPGA PC Engine clone.

This is more physically problematic(more wires, resistors etc) but less mentally stressful.

Thing is, without the ability to use tiny mchine soldered resistors/caps etc this would be the size of a damned table if it was done right.

Is it possible he did this? Yes.
Is it likely? No.

I agree. He is always anxious to tell people about what he has done or is doing, but when it comes down to some real good pictures, it's like he has an excuse rolodex.

I can't say that I buy this one. I'll probably be called a "troll" or a "stalker" for saying something negative about one of his mods, but thats the way I feel about it  <_<  

[blackevilweredragon]

i really don't care..  what i don't get though, is why you  brought back a dead topic, that was already scratched?

This is such an easy project, easier than SegaMac..  I don't see what the problem is..  This wasn't just out in one day, I did this one on my labs table..  It's so easy, follow the schematic, and you build a machine...

Even you guys can do this...  The schematics are freely downloadable online..  It shows every portion of the Genesis, that is required for operation...

[RobIvy64]

i really don't care..  what i don't get though, is why you  brought back a dead topic, that was already scratched?

This is such an easy project, easier than SegaMac..  I don't see what the problem is..  This wasn't just out in one day, I did this one on my labs table..  It's so easy, follow the schematic, and you build a machine...

Even you guys can do this...  The schematics are freely downloadable online..  It shows every portion of the Genesis, that is required for operation...

I think I speak for most people in this forum when I say that we are hardware guys. If you are building a Genesis from scratch, it's pretty much safe to assume that when you share the information, everyone is going to want to see it.

Lack of pictures is what has been plagueing the SegaMac project as well.

I could tell people that I built an Xbox from scratch, but I used a GeForce 4 GPU instead of the NV2A! That would be amazing right? When people asked for pictures of it and I say "Well I stubbed my toe and I can't walk over to the camera..." or something similar, they are automatically going to be skeptical, especially after the same treatment with multiple projects.

[blackevilweredragon]

but i can't provide pictures of this project, it doesn't exist anymore, that's what im trying to tell you..  when it wouldn't work, i gave up on the idea, and started borrowing parts from it, for other things (for one, fixing my mothers VCR--it runs on a Z80, that got zapped in a lightning strike)..

since this project is no-more, if i still had it, i would share pictures..  when SegaMac is done in development, I will share pictures of it's circuity..  and that may not be that far away, and you know me, i can't stay away from these forums, so it's not like im gonna run away from it..  there WILL be pictures, but i personally only like showing pictures of things that are finished..

[NFG]

The project as described is a large and difficult one, and in lieu of evidence skepticism is expected.

I'm pleased to see this thread hasn't devolved into a flame fest, good work.  </thinly veiled warning>

[GZeus]

Why bother?
I mean, I have respect for a dead horse, even if it was rabid when it was alive.

No, I don't know what that means...

[Epicenter]

but i can't provide pictures of this project, it doesn't exist anymore, that's what im trying to tell you..  when it wouldn't work, i gave up on the idea, and started borrowing parts from it, for other things (for one, fixing my mothers VCR--it runs on a Z80, that got zapped in a lightning strike)..

since this project is no-more, if i still had it, i would share pictures..  when SegaMac is done in development, I will share pictures of it's circuity..  and that may not be that far away, and you know me, i can't stay away from these forums, so it's not like im gonna run away from it..  there WILL be pictures, but i personally only like showing pictures of things that are finished..

Stop lying already. This is your third bout of nonsense. First your ridiculous posts on the UCM forums and this forum about your 'SegaMac', which you mysteriously won't show anyone photos of, which is tecnically impossible to function for a number of reasons, and which you showed an alleged video of operating, which displayed performance higher than that of genuine Mac systems with processors 8 times more powerful, and when this was pointed out, you apparently pulled the video offline. You have still yet to provide any proof that project is anything but a fantasy. When asked for any sort of technical information you changed your story many times to the effect that you had nearly 0 involvement in the project and your 'friends' did it. This fed into a discussion about 68010 installation wherein you demonstrated a complete lack of understanding of the relationship between 68000/68010 instruction sets and interoperability with Macintosh OS software further fueling an already concrete case against your claims.

After that, you started going on about a revolutionary little modification to fix "The problem" with MD/Genesis FM synth audio by feeding a new clock to the YM2612 chip. The problem didn't exist, and your 'fix' was even more preposterous. This endeavor resulted in your demonstration of near-complete lack of knowledge in not only how the MegaDrive/Genesis hardware functions at even the most basic levels (e.g. which components are housed in which Ics) but even basic electrical, logical, and microprocessor theory (a prime example would be when you stated FM audio quality was suffering because the 68000 processor 'sucks up the clock' and that a 68010 processor 'sucks up less clock'.)

There were also the lovely threads where you defamed the very concept of overclocking the MD/Genesis as dangerous and deadly to the console because you failed to perform the modification correctly where tens if not hundreds of persons, even with minimal or nearly nonexistant grasp of electronics, performed it correctly and with great success.

Now, you claim you've produced a clone of the MegaDrive/Genesis, which would be a monumental task given the number of components requiring connection. You mention that you used a real MD/Genesis GLU chip (building one from scratch would be virtually impossible without having a custom IC made for you, there's just too much logic to recreate). You mention using a 'TI noise generator'-- I can only assume you meant the PSG for generating audio, the one from the SMS that is also included in the MD/Genesis. It's already in the GLU chip, why on earth would you add another one? The VDP also, while based on an off-the-shelf Texas Instruments IC, is also a custom part and would likely require being built from the ground up to support all the features of the MD/Genesis' video subsystem correctly. Again, something that is pretty much impossible to rebuild with a bunch of gates and wire on a breadboard, and you'd be there for months if not years trying.

When challenged, you provide more ridiculous reasons than before (like the classic 'I have autism, so I can't explain how I put together my 'SegaMac' even though it probably took months to build'). You claim you just started yanking parts out your 'home-built Genesis'? If it existed, it'd probably be a PCB or breadboard with hundreds of hand-soldered leads, and require monumental effort to assemble-- yet you'd sacrifice all that hard work for a Z80, a CPU that can be bought in boxes of 50 for $10 on eBay and is probably the most common processor on the planet? And just like before, you can't/won't provide any photos of your work, except screen (fake) screen captures? And you wonder why people don't believe you...

Seriously, what is the deal with you? Are you just out for attention? Are you a pathological liar? Are you trying to get people's hopes up so you can shout 'Haha, I tricked you?' If the latter is your goal, I highly advise you find a different audience to fool, because you won't likely find on this forum many of the gullible people you're looking for.

My apologies to other board members than the OP if this comes across as spiteful, however I feel I need to set the record straight regarding this recent trend in threads before people start taking misinformation such as the OP has been spreading as fact.

[blackevilweredragon]

I never did use a real TI noise generator, because I learned it was in the VDP...

Perhaps if you saw the schematics yourself, you'd see, that, all the information to build a Genesis, is right there...  Only thing YOU need to do, is figure out the values of the resistors and capacitors..  And that's easy, they are marked on the real hardware.

EDIT:  Oh, and you do realize making your own PCB is easy..  get a blank copper board, use a laser jet to print on glossy paper, iron it to the copper board, and use the etchant to remove what you don't want...

that's how a lot of my circuits are built, otherwise it's a protoboard (which would NEVER happen with this project)

[Epicenter]

I have seen the schematics. In fact, I've got them right in front of me. I've been using them for YEARS and I am quite familiar with what information one can and cannot glean from them. The schematics indicate how the ICs are wired together, along with, of course, the locations in these paths of resistors, capacitors, diodes and other small components. They do not indicate in any shape form or fashion what goes on inside the ICs themselves. The 68K, Z80, YM2612, RAM, VRAM, power hardware, and analog AV hardware are off the shelf parts. But the VDP and GLU chip are custom parts and will need to be built from the ground up. The only logical feasible way to do that would be to analyze the original design for the TI part the VDP was based on, and to have immense knowledge of the internal operation of the GLU chip, and get custom ICs built to do the job. This would be incredibly labor-intensive and costly, especially just to have ONE chip made- the overhead would be enormous. And building them from smaller logic parts at home would be so much effort and require so many gates it's very close to impossible.

You have a LOT of explaining to do.

[blackevilweredragon]

I never built the custom ICs..  in the OP, i thought i could, then found out i couldn't..  I used them off the ORIGINAL hardware..  All I did, was rebuilt the system on a new motherboard, using all the original ICs, and removed some to get rid of room...  (audio amp was never used)

[NFG]

Yeah, OK, this is done.