RetroPort Review - Play NES games on your SNES!

RetroPort Review - Play NES games on your SNES!
by SatoshiMatrix on 2012-06-05 (#95038)

Hey guys, I'm finished my review for a cool device that came out recently that lets you play NES games on your SNES!

You can read my text review on my blog or watch the video review on my youtube channel or both!

Text review
http://satoshimatrix.wordpress.com/2012 ... rt-review/

Video review
http://www.youtube.com/watch?v=NTAvF-TPLhU

by Dwedit on 2012-06-05 (#95039)

Do player 2's start and select buttons work? Some clones don't support those.

by Shiru on 2012-06-05 (#95040)

Dwedit wrote:
Do player 2's start and select buttons work? Some clones don't support those.

Never heard of those, could you name some? They are modern, I suppose?

by Dwedit on 2012-06-05 (#95041)

I think the Tristar 64 was one of the clones that disallowed Select and Start on player 2's controller.

by Bregalad on 2012-06-05 (#95043)

The original Famicom didn't have any select or start buttons on controller #2, so many games were developed so that it doesn't require them.

by Bregalad on 2012-06-05 (#95045)

Quote:
As the SNES doesn’t have video feed pins through its cartridge slot, audio and video are provided to the RetroPort not by the SNES, but instead, an RCA to stereo 3.5mm headphone jack located in the side of the device.

And then I lost all interest in this.

I mean the whole point of using something like this is that you shouldn't have to jerk with your AV cables every time you move from your NES to your SNES or the other way around. But this don't fix the problem.

Seriously, if the SGB can use the SNES native graphics, there SHOULD be a way to do something in the like to the NES, right ?
For example, I don't know but preload a 56-color palette, and use one of the 8BP modes (mode 3 or 4) on the SNES side so that all colors can be acessed in any point of the screen, so it could display data like if it was a framebuffer.
Of course it would not handle the $2001 colour emphasis effects correctly, but anyway I doubt NOAC handles them correctly in the first place.

EDIT :
OK I made some computations, since the SNES has 64k of VRAM you can render 256x240 pixels at 8BP and it takes 60k or VRAM. You'd also need 2k for a dummy tile map (that would just be constant and consist of 0,1,2,...,959), and 2k remains free/unused.

Since we could use 256 colours on any pixel, but the NES uses only 53, we could even have up to 4 different colour emphasis per frame accurately.

However this would need to transfer the 60k of tile data every frame via DMA, which I'm not sure if it's possible.

by Hamtaro126 on 2012-06-05 (#95057)

Bregalad wrote:
Quote:
As the SNES doesn’t have video feed pins through its cartridge slot, audio and video are provided to the RetroPort not by the SNES, but instead, an RCA to stereo 3.5mm headphone jack located in the side of the device.

And then I lost all interest in this.

I mean the whole point of using something like this is that you shouldn't have to jerk with your AV cables every time you move from your NES to your SNES or the other way around. But this don't fix the problem.

Seriously, if the SGB can use the SNES native graphics, there SHOULD be a way to do something in the like to the NES, right ?
For example, I don't know but preload a 56-color palette, and use one of the 8BP modes (mode 3 or 4) on the SNES side so that all colors can be acessed in any point of the screen, so it could display data like if it was a framebuffer.
Of course it would not handle the $2001 colour emphasis effects correctly, but anyway I doubt NOAC handles them correctly in the first place.

EDIT :
OK I made some computations, since the SNES has 64k of VRAM you can render 256x240 pixels at 8BP and it takes 60k or VRAM. You'd also need 2k for a dummy tile map (that would just be constant and consist of 0,1,2,...,959), and 2k remains free/unused.

Since we could use 256 colours on any pixel, but the NES uses only 53, we could even have up to 4 different colour emphasis per frame accurately.

However this would need to transfer the 60k of tile data every frame via DMA, which I'm not sure if it's possible.

I rather go with a new system based on NES/Famicom hardware with a new PPU for a similar purpose.

But both seem to be farfetched, as PPU/VDPs are very hard and expensive to make, according to Tepples.

Also there is no real documents on how to make a PPU/VDP of your own kind. Which is a bummer...

by tokumaru on 2012-06-05 (#95058)

I don't think these "leech" (i.e. they only use power and input from the host console) devices are interesting at all.

EDIT: I wonder if games can read the extra buttons of the SNES controller...

by SatoshiMatrix on 2012-06-05 (#95061)

Bregalad, since you are much more techincally mnded than I, I wonder if there is any possible way to modify the RetroPort to actually use the SNES/SFC built in multi video out port.

My understanding was that it's impossible as there are none of the pins that export an NES video feed.

by Bregalad on 2012-06-05 (#95062)

While I know much about the NES hardware, I know few about the SNES.

This is basically a famiclone in a SNES cart, it's just they managed to use the SNES controller as well, so there is a 99% of chances it's impossible to mod it like you describe. Because they use a NOAC which output an analog video signal.

This should ideally be replaced with some kind of framebuffer (digital equivalent to a video signal) that sends frames to the SNES's VRAM. I'm pretty sure that's how the SGB works, although I have no details.
In the case of the SGB it was easier because the Gameboy only have 4 colours and a low resolution, while the NES has 52 colours and high resolution, so that's more data to transfer to the SNES each frame.

by SatoshiMatrix on 2012-06-05 (#95065)

Okay. Do you happen to have some insight on what value capacitor I should use to clean up the overamplified audio?

I've put in a 220kohm resistor (red red yellow) in parallel with a 3.3uf cap and that's yielded the best results so far. I've tried using a 0.1uf, 1uf, and 1.7uf cap already.

maybe looking at the pcb would help?

by Bregalad on 2012-06-05 (#95068)

Sorry but without any scematics I'm not sure what you're talking about.

If the audio is over-amplified you'd have to reduce the gain of the amplifier, which I'm not sure how it's made. If it simply uses an operational amplifier (?) then you should have a lower feedback resistor to reduce gain, but the circuit might not work like what I describe at all.

by marvelus10 on 2012-06-05 (#95086)

Its too bad they couldn't have wired it up like the TriStar/Super 8 then you would have only one set of A/V cables.

This device is like a compact version of the above mentioned with less features.

by SatoshiMatrix on 2012-06-05 (#95088)

except that the TriStar is a lot worse. Jailbar ridden video and reverse duty cycles in the audio, not to mention those damn deathgrips.

by Memblers on 2012-06-06 (#95129)

Actually I had played on the TriStar that kevtris had, and the sound was perfect. Maybe the DPCM was louder, I'm not sure because it was quite a while back. But I do know that every nes-on-a-chip clone I've tried since then has had the screwed pulse duty cycles. I suppose it's possible they changed to another chip during production. IIRC, the 'NOAC' was on it's own little carrier board, which would sorta suggest that.

by SatoshiMatrix on 2012-06-06 (#95131)

I own a Super 8/TriStar, and I'll post a video review of it soon.

by SatoshiMatrix on 2012-06-10 (#95294)

Dwedit wrote:
Do player 2's start and select buttons work? Some clones don't support those.

Yes, four player 2 buttons are mapped.

Sorry I didn't get back to you right away I forgot you asked this.