Do 2600 really dislike LCD monitors?

[SeaGtGruff]

According to Stella, "BASIC Programming" displays 264 lines, which fits my theory-- but "Solaris" displays 262 lines, which doesn't.

 

Edit: Unless "Solaris" occasionally displays more or less than 262 lines.

I don't think 2 extra lines would cause any problem on any display. Anyway IIRC Harmony does 262 lines exactly.

 

It could however be, that the monitor doesn't like vertical sync signal created by those carts. But since those carts don't roll on other monitors, I suppose that's a problem of the monitor not allowing the slightest difference to specification.

I may have been thinking about supercat's "Better Than Pitfall" music then, which I believe used 264 lines per frame (so it could call the music routine every 3 lines, if I remember correctly-- 262 not being divisible by 3, 264 being divisible by 3).

 

I think something being off in the vertical sync is the more likely answer. If Stan creates a list of carts/ROMs known to exhibit this behavior on certain LCD TVs, we can look at their vertical sync routines in the Stella debugger to see if there's anything out of the ordinary about them-- e.g., the exact cycles when VSYNC is turned on and off, whether or not VBLANK was left on during vertical sync, whether or not anything else is being done during vertical sync (such as strobing HMOVE or fiddling with the audio registers), etc. As far as I know, the only things that *should* interfere with vertical sync is whether or not VBLANK was left on by mistake, the duration of the VSYNC signal, or the cycles at which VSYNC was turned on and off (i.e., if it isn't being turned on quickly enough after a WSYNC).

 

Michael

[Thomas Jentzsch]

As far as I know, the only things that *should* interfere with vertical sync is whether or not VBLANK was left on by mistake, the duration of the VSYNC signal, or the cycles at which VSYNC was turned on and off (i.e., if it isn't being turned on quickly enough after a WSYNC).

That's what I remember now too. And instead of enabling VBLANK, a black background should work too.

 

But maybe you find something new.

[SeaGtGruff]

As far as I know, the only things that *should* interfere with vertical sync is whether or not VBLANK was left on by mistake, the duration of the VSYNC signal, or the cycles at which VSYNC was turned on and off (i.e., if it isn't being turned on quickly enough after a WSYNC).

That's what I remember now too. And instead of enabling VBLANK, a black background should work too.

 

But maybe you find something new.

I don't thinking setting the background color to black will be enough-- unless you either set the other three color registers to black, too, or at least move %00000000 to all of the graphics registers (all three playfield registers, the ball, both players, and both missiles). It would be far simpler (fewer writes) to just turn VBLANK on and off.

 

Also, some TV systems use "blacker than black" for the blanking level (PAL if I remember correctly, whereas NTSC's blanking level is the same as black-- or else it's the other way around), so setting all four color registers to black still might not be good enough if the TV insists that the blanking level is the only thing that will do.

 

Michael

[Thomas Jentzsch]

I don't thinking setting the background color to black will be enough-- unless you either set the other three color registers to black, too, or at least move %00000000 to all of the graphics registers (all three playfield registers, the ball, both players, and both missiles). It would be far simpler (fewer writes) to just turn VBLANK on and off.

Yes, that's what I meant to say.

 

Also, some TV systems use "blacker than black" for the blanking level (PAL if I remember correctly, whereas NTSC's blanking level is the same as black-- or else it's the other way around), so setting all four color registers to black still might not be good enough if the TV insists that the blanking level is the only thing that will do.

Usually you are right, but there are situations, where e.g. the background is the last displayed thing at the bottom and setting it to blank can be reused at the top of the screen.

 

Didn't notice that there is any visual difference between all black and VBLANK on. But maybe some TVs are very sensitive here.

[+SpiceWare]

Also, some TV systems use "blacker than black" for the blanking level (PAL if I remember correctly, whereas NTSC's blanking level is the same as black-- or else it's the other way around)

I don't know about PAL, but I do know that "Blacker than Black" is present in NTSC. Calibration discs display it on the brightness screen so you can adjust it to the proper level - if brightness is adjusted correctly, you won't see a difference.

 

Didn't notice that there is any visual difference between all black and VBLANK on. But maybe some TVs are very sensitive here.

See the last photo in #295 (page 12) over in the "Chung-Li" forum, it shows that it's visible if the brightness is misadjusted.

[Thomas Jentzsch]

See the last photo in #295 (page 12) over in the "Chung-Li" forum, it shows that it's visible if the brightness is misadjusted.

"Chung Li" forum?

[+SpiceWare]

Oops - Chun-Li, no G. Nathan's code name for that Melody based project were we first got Stella to run ARM code.

Edited April 13, 2011 by SpiceWare

[+stephena]

Oops - Chun-Li, no G. Nathan's code name for that Melody based project were we first got Stella to run ARM code.

Where exactly is this located? I've been looking for the forum where ARM support was added to Stella (and someone was supposed to send me a link for it), but I haven't found it yet.

[+SpiceWare]

pm sent

[SeaGtGruff]

It's interesting, I have the exact same problem, but only with two carts. Solaris and Basic Programming.

 

I use a Tosiba 20" flat CRT from probably 2002. There is no vertical hold control.

 

I've been dying to play Solaris (and I don't do emulators anymore.. ).

 

And I've used three different model VCSs (a heavy six-switch, a light six-switch, and a Sears Video Arcade II)..

 

Ah well..

I've hacked Solaris to see if it corrects the screenroll. I don't know if you have a programmable cart like a Krokodile Cartridge or the like, but if you can, try the hacked ROM to see if it fixes the problem for you.

 

Link to the hacked ROM

 

Michael

[WERY]

One thing that surprised me last time I checked out TVs was some of the newer sets are no longer including an S-Video connection - and they weren't the low-end models.

S-video is basically dead on consumer electronics, unfortunately. TVs and A/V receivers have both pretty-much abandoned S-video in favor of component and HDMI. There are ways around it, but they aren't cheap.

 

That is a reason to buy an european televisionset as they got SCART-connection and you can plug in S-Video cable into an adaptor that leads it into the SCART-jack. In case the signal does'nt work, the TV will convert the signal into C-Video or you use a S-Video>C-Video adaptor that combines the LUMA and CHROMA signals to one single C-Video signal.

 

Unfortunately these things are going away from the market so one has to use an expensive adaptor for converting SCART into HDMI. Some of the crappy TV's already have to use these adaptors to be able to display an image of the retroconsoles

[+SpiceWare]

That is a reason to buy an european televisionset

Not really an option on Planet Houston

 

use a S-Video>C-Video adaptor that combines the LUMA and CHROMA signals to one single C-Video signal.

I'm aware of that option, just prefer S-Video as it results in a better picture. Of course, composite is still better than RF.

[atarigal]

We have a 32" Vizio from 2008 and the only game we've found so far that rolls is Realsports Volleyball.

[AtariLeaf]

bumping a 2 year old topic because i hooked up one of my juniors to our toshiba 40" lcd and although most games worked fine, Jawbreaker came out in black and white with the screen rolling, although the cart works fine on CRT tv's. Does Jawbreaker have an odd scanline number?

[roland p]

264 scanlines according to stella

[AtariLeaf]

264 scanlines according to stella

is that an odd number that would cause this behavior?

[roland p]

It should be 262, so 264 is two scanlines 'too much'.

You can also check this list and test some games: http://www.2600connection.com/faq/vcs_scanlines/vcs_scanlines.html

[kid_vidiot]

you shouldn't even be using a PS2-era console on an lcd, least of all something as far back as a 2600.

[AtariLeaf]

I have a CRT TV and a Commodore 1702 that I use for gaming but they're still packed away and the wife wanted to play frostbite. Why, what can happen to the LCD?

[+McCallister]

I have a CRT TV and a Commodore 1702 that I use for gaming but they're still packed away and the wife wanted to play frostbite. Why, what can happen to the LCD?

I don't think anything happens to the tv. I've played on my LCD for long stretches without ill effect. I think the post might be referring to how classic consoles appear on lcds vs. a CRT?

[AtariLeaf]

So is this rolling problem going to occur for any game that isn't 262 scanlines on an LCD TV?

[Keatah]

Great topic and discussion. I would like to see a low-cost FPGA based adapter that can take composite and RF ch2-4 and simply output HDMI and VGA/DVI. And do it well. Perhaps have a usb port to update the FPGA (and software for any cores it runs).

 

Currently I use an old PC for this task. And while it works extraordinarily well, it's big, it's ungainly, it's loud, and power hungry..