[GBA] Classic NES Series Anti-Emulation Measures

[ccovell]

Wow, Loopy, I didn't know you did this kind of engineering. Very cool.

Got any adaptors that output 15khz RGB? (Y'know, simply for playing games?)

[mikejmoffitt]

Loopy, do you have any timing information you'd be willing to share? Any chance of the LCD being pretty close to NTSC already? I've been on an FPGA high recently, making capturers / line doublers for classic consoles that expose a pixel bus, but if the 3DS could use something more direct (like throwing a DAC onto the parallel LCD interface) that would be nice.

[tepples]

The DS master clock is probably supposed to be 2^25 = 33554432 Hz. According to GBATEK, it generates one dot every 6 clocks (5.592 MHz), one line every 355 dots (15753 Hz), and one frame every 263 lines (59.89 Hz). These timings are very close to the System M on which NTSC and arcade standard resolution are based, and the pixels through a supergun would be wider than square pixels (135/22=6.136 MHz) but not as wide as NES/SNES pixels (945/176 = 5.369 MHz).

That covers the top screen on the original DS, DS Lite, and presumably DSi, but adding the touch screen to the video output would still need a frame buffer.

[loopy]

The LCD timing is not NTSC friendly on the 3DS, you'd need a frame buffer. It's rotated 90 degrees (scanned bottom to top, left to right).

[mikejmoffitt]

The DS master clock is probably supposed to be 2^25 = 33554432 Hz. According to GBATEK, it generates one dot every 6 clocks (5.592 MHz), one line every 355 dots (15753 Hz), and one frame every 263 lines (59.89 Hz). These timings are very close to the System M on which NTSC and arcade standard resolution are based, and the pixels through a supergun would be wider than square pixels (135/22=6.136 MHz) but not as wide as NES/SNES pixels (945/176 = 5.369 MHz).

That covers the top screen on the original DS, DS Lite, and presumably DSi, but adding the touch screen to the video output would still need a frame buffer.

Interesting, it looks like that is indeed very close to NTSC timings for the DS. Perhaps something can be done there, then.

Loopy, do you think they are using LCDs that were originally designed for some other device that normally operated in portrait mode? The only other device that I've been aware of scanning in that way is the Dingoo A320, which uses an LCD designed for a flip phone.

[loopy]

They might have gone that way because of how the 3D is drawn (alternating left/right pixels horizontally).

[Drag]

The GP32 had a similarly rotated screen; the framebuffer in memory represented a 240x320 screen that was physically rotated 90 degrees to the left. This stuff does indeed happen.

[Asaki]

Got any adaptors that output 15khz RGB? (Y'know, simply for playing games?)

That would be awesome.

There's this, if you haven't tried it: http://community.arcadeinfo.de/showthre ... l-Overview

I've only tried it on one machine, and it said the drivers weren't supported. I'm going to have to try it on a desktop sometime soon. I have no way to hook up RGB to an analogue television, though, and it looks like that is a requirement.

Also, back to the original topic, there are IPS patches somewhere (they were very difficult to find) that defeat the copy protection. I used them to run the games on a GBA flash cart.

I believe N used the same method as PocketNES, where every four lines of background are compressed to three through temporal AA (lines 0, 1, 3 in even fields and lines 0, 2, 3 in odd), but some problematic tiles are modified to look better at 8x6.

Yeah, same thing as PocketNES, I seem to recall Flubba mentioning at one point being upset that Nintendo stole his idea.

Every tile is redrawn (not sure if by hand, or if they used a program), not just the problematic ones. You can hack the graphics into the original NES ROM and load it into PocketNES, set the graphics to "scaled BG, unscaled sprites" (I think) and it'll look the same.

[Dwedit]

Nintendo didn't just use the PocketNES scaling method, they patented it after seeing it in action.

[zzo38]

Nintendo clearly wanted to help GBA emulation become more accurate by subtly suggesting a couple of things that needed to be improved upon. Clearly.

Yes, it may be an internal conspiracy I think that is some of what happens. It is probably not the only reason though; rather someone suggested such thing to cause it to be more difficult, even though they want to improve the emulation in a same way too.