furrtek
patreon
Progress August I - Pretty much done
🕑 Added 2019-08-26 05:29:13 +0000 UTCSince a lot of work has been done by the MiSTer gurus and since there has been a whole month without any update from me, I thought it would make sense to write the last paid post now to summarize what has been going on, what's the (little) left to do, and at the same time cover the purchase of some equipment that's already helped a lot.
More on that below ;)
Sorgelig, Jamie and Jotego have done much more work than me for the project these last weeks, that's why a big part of the total amount I'll receive thanks to your support will be split and distributed to them.
The exact ratios aren't decided yet, but we'll talk about that and I'll disclose them in the next post if that suits everyone involved.
I feel that it's fair because they've spent a lot of time fixing bugs and increasing the memory capacity of the MiSTer for this particular core, so all-in-all that work not only benefits MiSTer users, but serves also this projects main goal: to have a precise, closest-to-100%-accurate NeoGeo logic definition.
This is the last paid post for this project because I'm now confident that most of the reverse-engineering part is done, and that I'll have enough funds from the last posts and this one to build the "verification board".
Apart from the board and its components, the purchase mentionned above was a $400 microscope and accessories (picture attached) to start getting into imaging chip dies myself.
As previously shown, I had the tools, chemicals and a now pretty solid routine set up for decapping 80's/90's plastic chips but except from discerning RAM or ROM blocks and getting clues on the tech used, I obviously couldn't discern individual gates and routing with the naked eye.
I've been told to stay away from Amscope if I could find a bargain on second-hand Olympus or Nikon microscopes, but those really aren't that common in Europe or they're reserved to medical or scientific research staff on dedicated auction websites (to which I can't register because reverse-engineering video game chips isn't "scientific research" according to them. Fair enough).
After days of looking at the options, I went for this kit expecting it would be good enough to at least recognize cells in gate arrays. Turned out to be better than expected since I can even clearly see the individual routing traces in the NeoGeo chip dies, which use 800nm tech from 1987.
This was a great surprise so I quickly got to image the NEO-C1 die which still hid a few secrets. It was done by recoding a 60fps HD video and manually "scanning" the die with the X/Y stage slow enough to reduce motion blur. Frames from the video were then extracted and stitched to form a hi-res image of the entire die.
This allowed to verify what was previously guessed (most was correct) and to figure out how the wait state generator worked. A few games rely on that to time their access to VRAM and avoid glitches, so it's quite an important detail.
Of course I didn't buy the microscope to only trace 100 gates on a single chip, I'm planning on tracing many more custom chips for preservation and/or repros if possible.Not thinking of a particular system for now but Konami, Capcom and Irem are at the top of the list :)
Here's what's left to do for the NeoGeo core:
-Fix the last YM2610 ADPCM bug(s).
-Get NeoGeo CDDA tracks to work. Logic is there but MiSTer wav file streaming isn't ready yet.
-Get trackball and Mahjong keyboard support.
-Get more Patreon rewards done ;)
To close this post I'd like to address a sincere THANK YOU to everyone of you who supported this project and inherently trusted me. From the beginning, the reception has been great and encouragements all along from so many people from so many countries had made it a great experience. With others who have worked on the project, I'm very happy to have provided enjoyment to arcade fans and participated in the preservation of a tiny part of the already vast video game history.
I'll be exposing the MiSTer setup and later on the verification board in a few expos in France and maybe other countries if I can lend it to people, along with a list of all those who helped and info sheets about the whole process.
