Gameboy Development Forum
Discussion about software development for the old-school Gameboys, ranging from the "Gray brick" to Gameboy Color
(Launched in 2008)
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#1 2015-10-19 11:26:40
- Denwey
- New member
- Registered: 2015-10-19
- Posts: 3
Looking for hires DMG/CGB CPU die shots
I am aware die shots for the DMG-CPU already exist, there's this one from tinytransistors.net but the resolution forbids detailed analysis (at transistor level).
I'm looking for something like NES' 2C02 shots. Does it exist already?
Last edited by Denwey (2015-10-20 07:18:10)
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#3 2015-10-20 07:12:57
- Denwey
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- Registered: 2015-10-19
- Posts: 3
Re: Looking for hires DMG/CGB CPU die shots
Mostly work on reverse engineering the video module, there aren't many docs on it, the one that most detailedly describes video behavior at cycle level is the Nitty Gritty Gameboy VRAM Timing, but it's solely based upon external logic analysis of the LR35902 package, not to mention it doesn't describe sprite reads. Knowing exactly what happens on the inside helps easily determine what will happen in every situation.
Perhaps we could have a Visual 2C02-like simulation of the chip then? 
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#4 2015-10-20 09:38:40
- Xephyr
- Member
- From: France
- Registered: 2015-02-26
- Posts: 59
Re: Looking for hires DMG/CGB CPU die shots
Well, it doesn't look like it exists unfortunatly. Maybe you can try looking for some similar architectures? The Game Gear does use a custom Z80 too and the same resolution (although it can support more colors), so it's maybe the same system. However, I don't know if you'll be able to find more informations on it.
I have to admit it's an interesting subject that said.
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#5 2015-10-20 17:47:40
- Denwey
- New member
- Registered: 2015-10-19
- Posts: 3
Re: Looking for hires DMG/CGB CPU die shots
I've looked at it already, but each of them are different on the inside, with different bugs. The OAM bug, for instance, is a clear example of the kind of thing I'm trying to document. They may have a pretty similar interface, but when implementing it, they fail in some things, surplus in others... y'know.
So I may now leave a request for the community: Do you happen to know someone who can do the Chip Decapping of the Game Boy's CPU, the LR35902?
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