That's 3 connectors (4 if you seperate the MIDI into 2 seperate connectors), and there's only room for 1 in an unmodified DMG shell.

IMO you should just leave unpopulated headers for people to add their own connectors, but that's just me. There's probably a better way.

This would allow you to have ALL the features of the Arduinoboy carry over through USB in one unit while overcoming the shortfalls of the Teensyboy being a slightly incomplete port of the Arduinoboy code (I think it's due to a lack of a certain kind of MIDI library for the Teensy 2.0 iirc).

pcb cost

Allow me to ask the most obvious question here: What about CPUs? The idea of new boards seems a little bit less exciting if you have to scavenge CPUs from old boards. Has anybody discussed reverse engineering the DMG CPU? The Chinese clones and K1 did it, both with more complex chips. It can't possibly be that impossible.

Also, the next biggest question: If you're going balls-to-the-wall to create the ultimate DMG board, what about an internal flash cart akin to that of the K1? Possibly accessible via the teensy's USB?

This. Yes. I know. Oh my. Yes.

I haven't found any online chip manufactures that sell the LR35902/8080/Z80/whateveryouwanttocallit CPU. A few claim to be able to fabricate some on demand, but that doesn't look as promising as it sounds. The emulator community has the instruction set well documented if full-crazy is the flavor of choice. But I feel like a 'first things first' approach -- upgrading the power supply and making sure I didn't totally faff up somewhere in the schematic -- seems like a more accessible milestone.
If an objective is to manipulate the DMG-CPU with the Teensy, stuff could get crazy. You could potentially go beyond a simple flash cart, and slave the DMG down to its core. As in, you could transcend LSDJ and have a computer-run tracker do everything except fabricate the actual sound.

But my inner evil genius knows well the taste of hubris.

Also, the next biggest question: If you're going balls-to-the-wall to create the ultimate DMG board, what about an internal flash cart akin to that of the K1? Possibly accessible via the teensy's USB?

Thus goes the story of my adventure: After consulting with xiwi over the construction of his original Arduinoboy kit, and his introduction of the Teensyboy to me, I thought there had to be a better way to hook up a DMG to a computer. I found Rolf’s work in Eagle, and came up with a plan. I Craigslist’d 2 DMGs, decimated one and scanned the bare board. I then imported the images into Eagle as rasters, compared against GB Dev, and traced. Once I got the CPU’s board completed, I made my initial post here. The Screen’s board was completed shortly after. Aggravated by the second board (I’m not ‘happy’ with whoever designed it), I dropped the project for a while to work on others. I came back recently, content to not recreate the second board to the same standard as the first, and mapped out the auxiliary boards. I packaged up everything I made to this point into two easily digestible Eagle projects and sent them to nitro. I then started work on the next leg of my quest.

But this is where I am now.

The plan is to do something much like what Rolf was attempting with the Arduinoboy, except with the teensy. Specifically, I want to have a board completely replace everything inside the Gameboy except for the screen’s board, without the need for anything but a tri-wing screwdriver, and run.  I want to have the Teensy’s USB accessible from the Link Port’s location, have a Li-ion battery, better power regulation (if such a combination is possible), and a better onboard headphone amp (with jumpers to bypass for prosound). I want to have the unused Teensy IO to be accessible for mods to the Teensy-duino code. And then I want to make it so it gets into the hands of anyone who wants it.

But that is where my quest will end, and not where I am now.

While I’m here, I thought I’d publish my scans of the front PCB.

Back's full size image | Front's full size image

And while I'm at it, here's all my DMG related plots in a single gallery.

pcb fabrication

I have family who's worked in intellectual property (patent prosecution), and have heard many 'a cautionary tale. One thing I've taken away is that everything, everything, can be contested. But things look good from here, especially when he reported a boost in sales

I should also mention, the inclusion of the AB is totally separate from the greater project. I'm much more inclined to use a Teensy, than an Arduino.

And, while I'm posting, I should mention that I've started work on the screen's PCB. And, as it turns out, I messed a few things up in my library (big surprise, right?). The pot the dmg uses is still very widely used today (Radioshack sells them), but I couldn't find a spec for them (that's Radioshack for you). It turns out that pins 1&2 are pre-pot, 2&3 are post-pot, and 5 is ground. Not surprising, right? What I didn't get is that 1&4 are one channel and 2&3 are for the other... There are several other things, this is just the most recent one. I'll update the plots when a final revision of the CPU PCB is made.

Re: programming header. I guess for one thing, I've become more size-conscious as of late. Using hole mount instead of surface mount already takes up a lot more space. Add a socket and the chips is now effectively twice as tall. But being able to use an external programmer beats having to extract a chip from a socket every day.

there is a lot of hard work which goes into making a PCB, a kit, or any product.  don't want to detract from that

like, if i laid out a kick-ass Aboy kit, i'd not be able to give people a yes or no about whether they could use the Aboy design in their own product.  its not my right to answer that question. 

that's all i mean

totally ignore this.  i'm just wordy today i think

i don't care so much, i mean its great you are bothering to even ask anyone because its shocking how that goes over some peoples heads sometimes, just figured i'd mention it. 

carry on   i'd still run it by trash80 though, even if its just out of some courtesy whether you 'have' to do it or not, you feel

(i'd ask trash80 is you're seeking permission if you feel you need to do this, its his project)

edit - i mean, since xiwi's kit is based of trash80's work, ask the original creator.  someone who did a work derived from the original or copied the original isn't who should be asked about using the original.  the creator is.  in this case, trash80. 

if its a technical question, have at it.  its unclear from the words.  i'm assuming you mean to ask for the permission.

Trash80 released the AB under a GNU license, which I'm pretty sure only covers the software, not the hardware. Xiwi could, if he really wanted to, get after me for using a directive of his hardware, even if it's based off Trash80's.
It's just a healthy dose of IP paranoia, and it's best to have written permission whenever possible.