Why nothing beyond 320x240? Why no interlaced screens?

[Gunstar]

Is the Jaguar incapable of doing better than 240 Horizontal scanlines? Can it not do an interlaced display at all? It is stated in the Jag FAQ that the resolution is programmable, from 160 (DOOM) to 800 pixels per line, which I naturally assume means that this resolution increase is ONLY horizontal? I've noticed that while the Saturn and Playstation don't use interlacing in-game (that I've seen), they do at least show static and/or menu screens in what appears to be something like 320x480 or 640x480 interlaced resolutions. Is the Jaguar not capable of something like this? And anyhow, why has no one ever used the higher horizontal resolutions, even for static displays before? Is it a memory problem? I could see why it could be a reason with Jaguar cartridges, but with JagCD it shouldn't be a a problem to include some high res screens...

[JagChris]

Probably a memory problem more than likely.

[Starcat]

Hi !

 

No. The reason for this is simple. In the dev manual there are two entirely different meanings to the word jaguar.

The first meaning is the Jaguar chipset. Many things that are listed in the JagFAQ like for example these resolutions are only true theoretically with the Jaguar chipset.

However the different meaning is when they actually talk about the jaguar console.

The Jaguar console however is fixed to about 240 vertial lines. You can't increase that as far as I know. You can change the the horizontal resolution by using a different multiplier in the video mode, howver that doesn't make much sense either.

 

So technically it can't be any higher than 240 in Y.

Another very obvious problem with higher video modes (in X direction, as Y can't be higher than 240) is simply that, why should it be done ?

A higher resolution would just mean that the OP would be a lot slower.

 

So unless you want to slow down the system, it doesn't really have any use.

 

I also don't really understand why somebody would want higher resolutions than 320x240 on the Jag... 320x240 was the standard resolution for consoles even to the N64 which came out in 1997, even after the Jag was gone already.

 

Regards, Lars.

[Tyrant]

Well, for a start, getting 640x480 would allow a dos sized text screen to be displayed I've never tried, but I *think* the Jaguar console can interlace .

[DracIsBack]

I seem to remember Atari talking about some games that used higher res screens than 320x240. But my memory escapes me.

[Mad Scientist]

I may as well add this question from the ignorant fringe:

There is an option in Tempest 2000 to turn interlacing on/off. How does that relate to this topic? I'm not suggesting that the game actually puts out an "interlaced" signal, but how does its output differ in terms of resolution (on an interlacing or non-interlacing diplay) when you select the non-interlaced option?

-MS

[ZylonBane]

The title screen for I-War appears to be 640x240.

 

And the "interlacing" in Tempest 2000 is just a jitter effect, not true interlacing.

[Gunstar]

Hi !

 

No. The reason for this is simple. In the dev manual there are two entirely different meanings to the word jaguar.  

The first meaning is the Jaguar chipset. Many things that are listed in the JagFAQ like for example these resolutions are only true theoretically with the Jaguar chipset.

However the different meaning is when they actually talk about the jaguar console.  

The Jaguar console however is fixed to about 240 vertial lines. You can't increase that as far as I know. You can change the the horizontal resolution by using a different multiplier in the video mode, howver that doesn't make much sense either.

 

So technically it can't be any higher than 240 in Y.  

Another very obvious problem with higher video modes (in X direction, as Y can't be higher than 240) is simply that, why should it be done ?  

A higher resolution would just mean that the OP would be a lot slower.  

 

So unless you want to slow down the system, it doesn't really have any use.

 

I also don't really understand why somebody would want higher resolutions than 320x240 on the Jag... 320x240 was the standard resolution for consoles even to the N64 which came out in 1997, even after the Jag was gone already.

 

Regards, Lars.

 

OBVIOUSLY, you missed the majority of what I said. I WANT higher resolution, for one, but I'm NOT talking about IN-GAME graphics, I simply thought it might be nice to see something higher resolution for the simple reason that higher resolution images LOOK better. I'm only talking about title screens, or static screens to look at while something loads, or static screens with text that tell the game story, etc. Static screens like this wouldn't put any undo load on the system or slow it down because there would be NOTHING to slow down! I'm just talking about pictures. For example, you could have used a higher horizontal resolution in your Ocean Depths cd and had better looking pictures, I'm sure you did those pics in a higher res originally, then lowered it to the Jaguar's standard resolution. If the Jag can't do interlacing, so be it, but a high res picture here and there could only enhance a game or "slide show." All those systems; Saturn, PSX, N64, etc, used 320-240, yes, but they also used higher resolution screens for exactly what I'm talking about.

 

Other than why anyone should want higher resolution, which I've given you my reasons, I thankyou for the info on what resolutions the Jaguar can do, and thanks for clearing up if it can to interlaced graphics or not.

 

Oh, and by the way, 320x240 was NOT the standard resolution on ALL consoles up to the N64; the 3DO uses an interlaced picture for EVERYTHING, in game or not. Either 320x480 (in game) or sometimes 640x480 for static screens. (it's actually a bit more technical in the way it displays the graphics, but they are interlaced; something about interpolation or something like that if memory serves, basically taking a 320x240 screen and displaying it in a 640x480 screen, blah, blah, blah)

[+Stephen Moss]

Although I know far less about the Jaguar video hardware than other here (almost zero) I do know a reasonable amount about display devices. True interlacing requires two vertical sweeps of the screen to display an image as all the odd lines are displayed on the first sweep then all the even lines are displayed on the second sweep and the combination of phosphur and visual persistance results in us seeing one complete image instead of two seperate images with every other line displayed as black.

Most monitors and TV's display an interlaced image and so technically most images are therefore interlaced even though they do not look it when displayed on a screen, an image viewed in its interlaced format would be unrecongizable.

 

Perhaps in this instance the term interlacing is being incorrectly use to mean Line Doubleing. Line Doubleing on the other hand does exactly what it says on the the tin as each horizontal line is displayed twice one directly below the other thus doubling the thickness of the line and therefore the height of the displayed image. Usually the only reason for doing this when an image is being displayed on a unit with a faster than expected vertical sweep/higher vertical resolution. In this situation doubling the lines should produce a normal looking picture as without it the image would appear long and thin in the center of the screen.

 

So technically it can't be any higher than 240 in Y.  

Another very obvious problem with higher video modes (in X direction, as Y can't be higher than 240) is simply that, why should it be done ?  

A higher resolution would just mean that the OP would be a lot slower.  

 

There is one possible reason for this although I am probably barking up the wrong tree and thats for producing game areas that are wider that the visible screen. With a horizontal resolution up to 800 pixels wide you could for example store the complete screen for a game such as Worms as one screen image (even though only 320 pixels may be visible at any one time) that can then be scrolled to display the rest of the playing area, otherwise you would have to create two different images for each half of the screen and mess about trying to make the join and match up in the middle which I suspect is more difficult and requires more programming.

I know that this example could be use for any resolution size in any direction but obviously the maximum size of any one screen is limited by the size of the hardwares available screen memory.

[Tyrant]

And the "interlacing" in Tempest 2000 is just a jitter effect, not true interlacing.

Umm.... wtf!?

 

Explain to me please why Yak would create a "fake" interlace mode in Tempest?

 

If it says interlace, it looks like interlace, and the Yak put it there, I for one would tend believe that it really is interlacing. What exactly do you base your opinion that it is not on?

[ZylonBane]

Most monitors and TV's display an interlaced image

Uhh... well, you're half-right. Most monitors run progressive scan, not interlaced.

[Trip_Cannon]

I always thought the interlaced mode in Tempest 2000 was for output on monitors (rather than TVs). Cause Jaguar had that option right? I've never tried it... anybody else out there who has?

[Stone]

And the "interlacing" in Tempest 2000 is just a jitter effect' date=' not true interlacing.[/quote']

Umm.... wtf!?

 

Explain to me please why Yak would create a "fake" interlace mode in Tempest?

 

If it says interlace' date=' it looks like interlace, and the Yak put it there, I for one would tend believe that it really is interlacing. What exactly do you base your opinion that it is not on?[/quote']

Just turn it on and look at it: he does have a point; that's what it looks like.

 

Next time I see Jeff I'll ask him, how's that?

 

Stone

[Symmetry of TNG]

And the "interlacing" in Tempest 2000 is just a jitter effect' date=' not true interlacing.[/quote']

 

 

I remember the 1st time i saw T2K and the "2000" points swiching past my head.. "AMASING i thought the jaguar is so fast it can handle so meny points realtime".

 

Today (years of jaguar coding experience later) I know how he did it! =)

 

And my point beeing is that Jeff is a True Hacker! (salute 2 u!) and it is the visual result that matters how you get there is another matter. But the hacker always explore HW tricks & "cheat" (if you like) to get there... but then you dont need a P5-8GHz to view the same result either =)

 

 

I am shure that "interlace" whatever it realy does has some nice thought behind it.. (half screen, doubled, to always get 50fps or whatever, or perhapps just a nice "nostalgia" effect since he seem to be a computer grafixs/ visual effects explorer =) something I for one like (from the ST scene) and miss on the jaguar.

 

ahh well... =)

About Higher rez on the jaguar. I'll keep it in mind and see what i can do

 

cheers

/El Hacker :-P

 

"Infinite Bobs on the ST can blow the mind out of a PC "coder"..." ;-D

[Matthias]

Hello!

 

 

In "The Jaguar Engine" Bitmaster had implemented a 640*480 screen (non-interlaced) for presenting the "hires" TOS/GEM-desktop.

Looks good on a VGA-monitor

 

Regards

Matthias

[bigferret]

As to the "interlace" issue in T2K, it is not true interlace at all. I recall Yak mentioning on his own forums that it was originally planned to have the feature, but was scrapped - thus the jiggly action Zylon mentioned.

[Paolo]

... and if I remember correctly, the flickering effect happens in the wrong direction: it should flicker up and down, but it does it sideway...

[Symmetry of TNG]

some short test later:

T2K "interlace" flickers in x direction, true.. not in y as usual... dont realy know what it does actually? ...also i didnt notice it when playing only in options menue (ok i might have been to buzy shooting THEM! THEM! THEM!

 

 

In the demo stage:

720x240 is defenitely doable! (16bit CRY or RGB)

1440x240 should also be doable in an easy way (ie supported by jaguar console hardware).

 

in Y direction... well give me some more debuging time, yesterday I got half way to interlace but i need more time

 

Though how to get 480 without interlace on a TV i dont know... (is it possible?) i just know that all ST computers (& the falcons VIDEL chip that is similar to the jaguars have interlace if res is higher than 240).

That would be interesting to know how it is done.

 

But i agree... if u have a CD as medium then any menue or stills SHOULD be in higher rez... why? because it can! =)

 

Where can i download the Jaguar Engine or what it was called?

 

cheers

/Sym

[Matthias]

Hello!

 

Where can i download the Jaguar Engine or what it was called?

 

TJE was on the first JDC-CD, you can also find a tv-friendly version on my Jaguar-webpage (look into video.s).

Here is the function which sets the video-system-registers to produce a VGA-picture (I think VMODE is set to $187 for this), call VideoTiming() with d0 = 2:

 

 

 

//---------------------------------------------------------------------

// VIDEO.S

//---------------------------------------------------------------------

   .globl	VideoTiming



VideoTiming:	movem.l	a0-a1,-(sp)

   and.w	#0x3,d0

   lsl.w	#2,d0  //*4

   lea	video_tab,a0

   move.l	(a0,d0:w),d0

   beq.s	unknown

   move.l	d0,a0

               lea     0xf00000,a1	// TOM

               move.w  (a0)+,0x2e(a1)

               move.w  (a0)+,0x34(a1)

               move.w  (a0)+,0x36(a1)

               move.w  (a0)+,0x54(a1)

               move.w  (a0)+,0x32(a1)

               move.w  (a0)+,0x30(a1)

               move.w  (a0)+,0x3c(a1)

               move.w  (a0)+,0x38(a1) 

               move.w  (a0)+,0x3a(a1) 

               move.w  (a0)+,0x3e(a1)   //Vertical

               move.w  (a0)+,0x42(a1)

               move.w  (a0)+,0x46(a1)

               move.w  (a0)+,0x48(a1)

               move.w  (a0)+,0x40(a1)

               move.w  (a0)+,0x4a(a1) 

               move.w  (a0)+,0x44(a1) 

               move.w  (a0)+,0x4c(a1) 

               move.w  (a0)+,0x4e(a1)



unknown:	movem.l	(sp)+,a0-a1

 rts

   



video_tab:	dc.l	tv50, tv60, 0, vga60





//##################################################################################

tv50:           dc.w	850  // HP: 1 Halbzeile = 851 Takte

               dc.w  	0x0400+725	// HS: HSync, 2.Halbzeile Pos 725

               dc.w  	0x259   // 724  // HVS: End VSync, 724

               dc.w	787  // HEQ: - End, 787

               dc.w	158  // HBE: Blank Ende 

               dc.w  	0x0400+687	// HBB: Blank Begin, 2.Halbzeile

               dc.w  	0x6a0   // 0x0400+509	// HDE: Display-End, 2.Halbzeile

               dc.w  	0xa6    // 398  // HDB1: Display-Start1

               dc.w  	0xa6    // 398  // HDB2: Display-Start2



//-------------- Vertical ----------------------------------------------------------



               dc.w  	623  // VP: Vertical-Period

               dc.w  	34  // VBE: Vertical Blanking End

               dc.w  	0x2e    // 92  // VDB: Vertical Display Begin

               dc.w  	0x1be   // 240 Zeilen = 0x20e   //572  // VDE: Vertical Display End

               dc.w  	600  // VBB: Vertical Blanking Begin

               dc.w  	613  // VBE: Vertical Equalization Begin

               dc.w  	618  // Vertical Sync

               dc.w  	6  // VEE: Vertical Equalization End

               dc.w  	573  // Vertical Interrupt, nur ungerade Werte !



//##################################################################################

tv60:           dc.w  	844  // HP

               dc.w  	0x06cd  // HS

               dc.w  	0x028b  // HVS

               dc.w  	0x030e  // HEQ

               dc.w  	0x7d  // HBE

               dc.w  	0x06b1  // HBB

               dc.w  	0x400+467	// HDE: Display-End

               dc.w  	350  // HDB1: Display-Start

               dc.w  	350  // HDB2: Display-Start



               dc.w  	523

               dc.w  	24

               dc.w  	46  //Display-Beginn

               dc.w  	486  //Display-End

               dc.w  	0x01f4

               dc.w  	0x01ff

               dc.w  	0x0205

               dc.w  	6

               dc.w  505





//##################################################################################

// VGA



//Horizontal Pixelclock = 26,6 Mhz 844 Takte

//1 Zeile = 844 Takte

//Sync:          98

//Porch:         22

//left:          42

//Display:       640

//right:         42

//Front:         0



vga60:          dc.w	844/2-1  //1 Halbzeile, 844 Takte

               dc.w  	0x0400+324	//HSync, 2.Halbzeile Pos 324

               dc.w  	323  //HVS End VSync, 601

               dc.w	1  //HEQ - End, 787

               dc.w	22  //Blank Ende (22)

               dc.w  	0x0400+324	//Blank Begin, 2.Halbzeile

               dc.w  	0x0400+282	//Display-End, 2.Halbzeile (282)

               dc.w  	64  //Display-Start1 (64)

               dc.w  	64  //Display-Start2



//-------------- Vertical ----------------------------------------------------------



               dc.w  	1049  //Vertical-Period, 1050 Halb-Zeilen, kein Interleave

               dc.w  	2*32  //Vertical Blanking End

               dc.w  	2*32  //Vertical Display Begin

               dc.w  	2*513  //Vertical Display End

               dc.w  	2*513  //Vertical Blanking Begin

               dc.w  	-1  //Vertical Equalization Begin

               dc.w  	1046  //Vertical Sync

               dc.w  	6  //Vertical Equalization End

               dc.w  	1027  //Vertical Interrupt, nur ungerade Werte !

 

Regards

Matthias

[Matthias]

Hi,

 

seems you have to call VideoTiming() with d0 = 3:

 

video_tab:   dc.l   tv50, tv60, 0, [b]vga60[/b] 

 

Sorry,

Matthias

 

PS: Still no editing allowed?