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Sega saturns resolution outputs
croft - Oct 8, 2005
  croft Oct 8, 2005
Hi all,

Wonder if someone can help me please.

I have read on the net that the sega saturn had various tv operating modes including SVHS , RGB , EDTV , VGA.

These outputs were apparently programable.

My main question is if the higher resolution formats like EDTV and VGA are indeed possible.?

Also what is EDTV? , Some sort of Japanese res?

I understand that the games have to be programmed for higher screen res aswell,Could this simply mean a patch?

I managed to bypass the security ring issue using a boot disk / disk swap method which works untill the machine is switched off.

It would be awsome to think of games like radiant silvergun running on a monitor or projector and in high res

Any info would be greatly apreshiated.

 Quick Man Oct 8, 2005
The Sega Saturn is capable of four different resolutions:

320 x 240

352 x 240

640 x 480

704 x 480

They're selected with registers on the VDP2 (to select the resolution between the top two and bottom two) and the SMPC (to change the system clock which chooses the top or bottom of each pair).

Charles MacDonald... is more lucid than I am on the subject.

In any case, I severely recommend you get a modchip if you do not want to kill your Saturn's motor in the long run.

 RockinB Oct 8, 2005
Don't forget the NTSC vertical resolutions of

224 and 448.

To my knowledge, there is a special resolution for the high res display (or whatever you may call it).

 croft Oct 8, 2005
Hi Quick man,

Thankyou for the great information dude :thumbs-up:

Thats very interesting.

I often wondered what the Saturn was capable off.

Thanks for the advice on the lens.

I do have a chip somewhere but have not installed yet.

The boot disk does a good job and only needs to be done once.

But like you say each swap to trick to get it done does take it out of the machine.

I have about 7 spares just in case.

Thanks very much for the info,

Ian. (UK). :thumbs-up:

 cgfm2 Oct 9, 2005

  
	
	

		
		

			Originally posted by croft@Sun, 2005-10-09 @ 09:25 AM



My main question is if the higher resolution formats like EDTV and VGA are indeed possible.?  



Also what is EDTV? , Some sort of Japanese res?




[post=140507]Quoted post[/post]


Yes. The Saturn can output VGA (640x480 non-interlaced) and EDTV (704x480 non-interlaced). I think the VGA timings are standard (31 KHz) but EDTV isn't (32KHz? It's been a while since I checked).

VGA and EDTV modes only work on the RGB output of the Saturn, the composite and s-video outputs can't handle it. If you a decent multisync monitor either mode will work fine. Somewhere around here I wrote some demos using both modes as a proof of concept test, perhaps I should dig those up.

EDTV is supposed to be another format that fits between SDTV (standard) or HDTV (high-def). The only real difference is the non-interlaced display. It was introducted quite a while ago in Japan by NHK who made a big push, so EDTV did well there. However it appears to be much less common outside of Japan, and rather than adopting some intermediate format it seems most people made the leap from SDTV to HDTV directly.

Sorry to say games cannot be patched to output in VGA or EDTV. Enabling these modes has some weird restrictions:

The VDP1 framebuffer isn't big enough to be shown properly in a non-interlaced display. A VDP1 control bit has to be set which causes the framebuffer to be sampled at 1/2 the horizontal frequency and twice per scanline, effectively doubling the framebuffer pixel size. So for a 640x480 display, the VDP1 graphics appear 320x240 (very chunky looking).

VDP2 can't actually display graphics at the VGA or EDTV scan rate. Only NBG0 and NBG1 are available, and they are sampled every other pixel (effectively reducing VRAM transfer to the same 15KHz rate normally used). The odd pixels are empty (transparent).

So to display a full-screen image, you have to split the graphics up between NBG0 and NBG1, enable both of them, and shift NBG1 over by one pixel.

Beause of these considerations, games would need a signifcant amount of reprogramming to work properly. I would have loved to see VF Remix in VGA-resolution running at 60 FPS.

 RockinB Oct 9, 2005
I don't know if there is any difference to non-interlaced display, since the display on TV is done in half-frame.

EDIT: so it would require a display device displaying full frames?

Someone told me that a half frame displays only every other line. I still can't combine this with a camera shot I made from TV, which just showed the upper half of screen. Confusion...

 cgfm2 Oct 9, 2005

  
	
	

		
		

			Originally posted by Rockin'-B@Sun, 2005-10-09 @ 12:27 PM



I don't know if there is any difference to non-interlaced display, since the display on TV is done in half-frame.



EDIT: so it would require a display device displaying full frames?



Someone told me that a half frame displays only every other line. I still can't combine this with a camera shot I made from TV, which just showed the upper half of screen. Confusion...




[post=140522]Quoted post[/post]


The thing you are talking about (half frames) sounds more like a standard interlaced display. Interlaced displays are composed of two half frames (262.5 scanlines) shown at 60Hz, due to persistance of vision it appears to be one 525-line screen updating at 30Hz. But a little flickery.

In comparsion for a non-interlaced display you have single 262 line frames shown at 60Hz, with a noticable gap between the scanlines where the other frame would go if the display was interlaced. There's no gap in the interlace or VGA/EDTV modes.

For both EDTV and VGA, the Saturn outputs 480 scanlines per 60 Hz frame. You do need a special monitor because the scan rate is 31KHz instead of the standard 15 KHz; this is beacuse it is outputting double the amount of scanlines (I believe 525 instead of 262 but haven't checked the total VGA/EDTV scanline count) in the same amount of time.

Hmm, I suppose we can't use EDTV/VGA modes for the C4 competition.