Sizecoding wiki

[42bs]

I added some info, but needs more content:

http://www.sizecoding.org/wiki/Atari_Jaguar

[Cyprian]

great.

 

I'm not sure about that "It can display up to 720x240 pixels in various ways". As far as I remember it supports higher resolution:

Supported horizontal resolutions are:
- 1400 pixels (NTSC) /1382 pixels (PAL)
- 700 pixels (NTSC) / 691 pixels (PAL)
- 466 pixels (NTSC) / 460 pixels (PAL)
- 350 pixels (NTSC) / 345 pixels (PAL)
- 280 pixels (NTSC) / 276 pixels (PAL)
- 233 pixels (NTSC) / 230 pixels (PAL)
- 200 pixels (NTSC) / 197 pixels (PAL)
- 175 pixels (NTSC) / 172 pixels (PAL)

Supported vertical resolutions are:
- 1400 pixels (NTSC) /1382 pixels (PAL)
- 480i (NTSC) / 576i (PAL)

 

Edited March 11, 2022 by Cyprian

[42bs]

I am not sure the interlace modes really work. But I will check (should be simple ? ).

[Cyprian]

cool, worth to check that:

 

there is an interesting topic with an interlaced graphic setup code:

https://www.jagware.org/index.php?/topic/352-high-res-graphics-on-the-jaguar/&tab=comments#comment-13038

 

 

and another example with VGA compatible mode:

 

Edited March 11, 2022 by Cyprian

[42bs]

Wow, rather complicated. No wonder, any game uses it. Quick scan seems, one has to handle even/odd display manually

[Cyprian]

6 minutes ago, 42bs said:

Quick scan seems, one has to handle even/odd display manually

that strange, especially that is a hardware support in OP for interlaced objects

Edited March 11, 2022 by Cyprian

[42bs]

I remember Normen from Atari told us (_us_ that's Phobyx): "no interlace".

 

Edited March 11, 2022 by 42bs

[Zerosquare]

Interlaced modes are not really documented and there are a few gotchas, but yeah, they do work:

http://www.jagware.org/index.php?/topic/230-haute-résolution-sur-jaguar-et-mode-entrelacé/&do=findComment&comment=3833

 

It's also possible to drive a VGA monitor at 640x480 @ 60 Hz noninterlaced. I've done it, but not released the code, as I didn't manage to make it work without a little external circuit to clean up the sync signals (the plan was to get something working with just a passive cable).

 

4 hours ago, 42bs said:

I remember Normen from Atari told us (_us_ that's Phobyx): "no interlace".

One more proof you shouldn't trust Atari's word too much

Edited March 11, 2022 by Zerosquare

[Chilly Willy]

10 hours ago, 42bs said:

Wow, rather complicated. No wonder, any game uses it. Quick scan seems, one has to handle even/odd display manually

The N64 is the same way. You have to manually change all the settings every vblank. I made the changes in libdragon for proper N64 interlace after trying to use interlace and noticing it didn't work properly. That was (checks calender), damn, almost a decade ago!

 

[Cyprian]

9 minutes ago, Chilly Willy said:

The N64 is the same way. You have to manually change all the settings every vblank. I made the changes in libdragon for proper N64 interlace after trying to use interlace and noticing it didn't work properly. That was (checks calender), damn, almost a decade ago!

 

in the Jag you have to set all those video registers only once (the same registers set as in the Falcon) at the beginning. And then vblank you have to set the only OP list as usual and in case of interlace just set properly VI register.

[42bs]

7 hours ago, Cyprian said:

just set properly VI register

You mean, every interrupt you have to reset it? Odd for the one half frame and even for the other?

[Cyprian]

1 hour ago, 42bs said:

You mean, every interrupt you have to reset it? Odd for the one half frame and even for the other?

 

That's a quote from: https://www.jagware.org/index.php?/topic/352-high-res-graphics-on-the-jaguar/&tab=comments#comment-13038

 From now on, you can test whether the current field is the top one or the bottom one by testing bit 11 of the VC register :
- if it's clear : top field
- if it's set : bottom field 

If you use the 68K VBL interrupt, you also need to dynamically alter the value of the VI register, otherwise the interrupt won't trigger :
- for top field : VI must have bit 0 cleared (even value)
- for bottom field : VI must have bit 0 set (odd value)

 

Edited March 12, 2022 by Cyprian

[Chilly Willy]

23 hours ago, Cyprian said:

in the Jag you have to set all those video registers only once (the same registers set as in the Falcon) at the beginning. And then vblank you have to set the only OP list as usual and in case of interlace just set properly VI register.

Oh, so it's actually better than the N64 for interlace. ?

[42bs]

Mandelbrot set with GPU/DSP in parallel (pixel wise interleaved):

https://github.com/42Bastian/new_bjl/tree/main/exp/tj_mandel_256

mandel_256_j64.zip

 

Edit: Oops, wrong topic

Edited March 22, 2022 by 42bs