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Players and Developers: What Is The 7800 Doing...

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...After you press the power button?

 

Let's see...

 

1-3 SECONDS --> 15-30 SECONDS --> 1 MINUTE

2 MINUTES --> 5 MINUTES --> 8 MINUTES

20 MINUTES --> 1 HOUR --> 5 HOURS

 

post-18-0-16891500-1362950912_thumb.pngpost-18-0-81096800-1362950913_thumb.pngpost-18-0-30170000-1362950915_thumb.png

post-18-0-85579200-1362950916_thumb.pngpost-18-0-35892800-1362950918_thumb.pngpost-18-0-81608200-1362950919_thumb.png

post-18-0-13846000-1362950923_thumb.pngpost-18-0-83532500-1362951302_thumb.pngpost-18-0-41316700-1362951304_thumb.png

 

ANSWER...

It is Phase Shifting.

 

Yeah, you know what this means...

More coming soon.

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Interesting experiment. Not too suprising though, considering the phase shift is adjusted with a variable resistor. Any components in that circuit whos resistance varies with temperature will change over time as the unit heats up. It would be interesting to see how it changes with the cover off. Maybe someone could come up with a fan mod?

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I've noticed this same thing happens on the 2600 too.

 

EDIT: Did you take those pictures with the flashbulb on?

Edited by Bakasama

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Actually, I don't know what this means..

 

Is this leading up to another new video mode like the one someone found by nearly frying his Atari computer?

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What it means is that no matter how hard someone tries to come up with a did unitive set of color palettes for Atari 7800 emulators, it is an exercise in futility. There are just too many variables involved to get anything "exact", so you have to strive for a happy medium, like I did with my final NTSC color palettes for Prosystem many moons ago.

 

What I do notice is the longer the 7800 is left on, the further the phase shift pulls the color palette on real hardware closer to the desired colors, as opposed to what most people have settled for as the "default" 7800 color scheme.

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Interesting experiment. Not too suprising though, considering the phase shift is adjusted with a variable resistor. Any components in that circuit whos resistance varies with temperature will change over time as the unit heats up. It would be interesting to see how it changes with the cover off. Maybe someone could come up with a fan mod?

You wouldn't really want a fan mod. The colors look Waaaaaaay better ones it's all warmed up. If anything, you might want to warm it up quicker.

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So between what is offered as the "FINAL" NTSC and PAL colors in the other thread and what is being posted here, you can pick which is best for you and your situation or/and experience.

 

A7800_PHASE_SHIFT.zip

 

There are 10 palettes for each region being posted. PHASE 25.7 of course is the 'technically accurate' one and approximately [these are raw palettes] what you see between ~15 seconds and few minutes the system is powered on in the screenshots from the initial post.

 

The complete variety is as follows:

 

PHASE 24.2 --> PHASE 24.7 --> PHASE 25.2

PHASE 25.7 (Documented/technical accurate if no 'cool/heat' issues were present)

PHASE 26.2 --> PHASE 26.7 --> PHASE 27.2

PHASE 27.7 --> PHASE 28.2 --> PHASE 28.7

 

This provides a 1.5 degree cooler palette from what is supposed to be 'default', up to a 3 degree warm up to the color palette (Yes, it does get even slightly cooler and warmer than this extremes, but these cover fair enough the gambit for practical purposes).

 

NTSC:

post-18-0-96173200-1362965879_thumb.pngpost-18-0-31817900-1362965881_thumb.pngpost-18-0-64714200-1362965883_thumb.png

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post-18-0-17741800-1362965894_thumb.pngpost-18-0-71190200-1362965895_thumb.pngpost-18-0-33819300-1362965897_thumb.png

 

 

PAL:

post-18-0-52178900-1362965992_thumb.pngpost-18-0-19318200-1362965994_thumb.pngpost-18-0-84878500-1362965995_thumb.png

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post-18-0-96570300-1362966004_thumb.pngpost-18-0-56484100-1362966006_thumb.pngpost-18-0-57512500-1362966007_thumb.png

 

 

NTSC IN-GAME:

(24.7 --> 25.7 --> 26.7 --> 27.7)

post-18-0-34423900-1362966384_thumb.pngpost-18-0-65341900-1362966385_thumb.pngpost-18-0-21017600-1362966387_thumb.pngpost-18-0-84480300-1362966388_thumb.png

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PAL IN-GAME:

(24.7 --> 25.7 --> 26.7 --> 27.7)

post-18-0-97145300-1362966464_thumb.pngpost-18-0-40920300-1362966466_thumb.pngpost-18-0-47819900-1362966467_thumb.pngpost-18-0-98117100-1362966468_thumb.png

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What it means is that no matter how hard someone tries to come up with a did unitive set of color palettes for Atari 7800 emulators, it is an exercise in futility. There are just too many variables involved to get anything "exact", so you have to strive for a happy medium, like I did with my final NTSC color palettes for Prosystem many moons ago.

 

With all due respect, the palettes I have been offering up are not "hand-picked" or "selectively tuned" which seems to be the case with the 'happy medium' in ProSystem and is way off in some cases (Bentley Bear). The color saturation and overall brilliance is extreme past any specs for some of the values - There is not a normal/progressive scale of dark --> light and vice-versa. The color gradient is not possible.

 

Don't get me wrong, it is good without utilizing any technical specs and just eyeballing it with a dash or two of personal preference, it did come out pretty well. But honestly, I think these palettes that have been posted over that last couple of months are an improvement and offer up much more realistic variety and selection than what was created a few to several years ago.

 

I don't think it is an exercise in futility. I believe somewhere down the road we will have a 7800 emulator that has NTSC emulation/controls while also emulating system/warm-up with the palette changes over the course of time. Look at the amazing talent we have seen so far.

 

I can't help but again think how it was only a couple of years ago when it was thought there was no way to even add POKEY sound to Donkey Kong without the original source code or needing to start from scratch....Just look at where we are now. And who the heck would have ever thought of anything like Bentley on the 7800 existing - even without the XM/music, the game is beyond anything that was around a couple of years ago for the system.

 

It is all a matter of time...and maybe, just maybe this might help or ignite a spark for someone to modify or create a 7800 emulator that does just what is experienced with the hardware regarding colors.

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I've noticed this same thing happens on the 2600 too.

 

EDIT: Did you take those pictures with the flashbulb on?

 

No..but I did take dozens upon dozens of pictures. Some with the flash, others no flash.

This ones posted are only a select few and they have been scaled down in resolution so not to kill bandwidth.

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Understandably, there are differences between systems, setups, displays, etc. For the record, let me state as testing ground was two different 7800 from two completely different setups and motherboards; both providing the same results.

 

1. Atari 7800 with composite out - modification on Longhorn Engineering with no Expansion Module Interface or cut-out/spot on the motherboard.

 

2. Atari 7800 with composite out - simple mod with a few resistor and bridges complete Expansion Module Interface present.

 

It could be that both these 7800's coincidentally have the same issue(s) and setting(s) which causes these specific changes, but that is probably highly unlikely.

 

Again, Phase Shift 25.7 - would be the 'documented' accurate one; however a more preferential choice for me is 26.7 - 27.7 as that is the average of about how long I play the system in a typical sitting, and therefore the colors I experience most.

 

Your experience will vary. Again the most extremes are either very short lived or/and least experienced and encountered while playing a game and no need to include them unless requested.

 

Some games the color shifts are not nearly as noticeable (Dig Dug, Joust, Desert Falcon) as the other extreme (Choplifter) where it is highly visible. Then again, region makes a difference too as the aforementioned Choplifter hardly changes in PAL territory.

 

For developers, that may help some in trying to decide which color value(s) to select. For the players, you have more options than ever to pick the palette and colors that match your system and scenario best.

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Even though I am not a programmer for the 7800 I will chime in with this....

 

We have to realize that all the 7800 hardware was based on 80's technology...which is no where near what we have today.. if the 7800 were to be made today this discussion would have never taken place.

 

Emulators are never going to be perfect...that is a fact of life.. but what Trebor has done is nothing short of amazing...I commend him for his labor of love and has made my 7800 emulation experience a better one because of it.

 

All this debate about emulation vs hardware...to me it is all a matter of preference...

 

Emulation offers a way of playing the games without having all the hardware headaches and maintenance issues that pop up all the time.

 

Real hardware offers its own reward in that you have a physical piece of history...however sooner of later real hardware fails..and will become non obtainable. (unless someone buys the rites and manufactures the consoles)

 

Let us just say that there will always be people that like it one way over the other and leave it at that.

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...what Trebor has done is nothing short of amazing...I commend him for his labor of love and has made my 7800 emulation experience a better one because of it.

Thanks NIKON, I appreciate it.

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I wonder if this is related to a failing voltage regulator. I know the colors on the 2600 will have a similar issue when the voltage regulator is starting to go. I haven't really ever tested this out on the 7800 though.

 

Mitch

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When I tried KevinMos3's color edit hack for Tank Command using my CC2 it wasn't the color he intended until my 7800 warmed up. After looking at this I'd guess he probably picked a color that was close to the edge of tan and green at the bottom because if I remember correctly it would start green but then later be the tan color he intended.

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I wonder if this is related to a failing voltage regulator. I know the colors on the 2600 will have a similar issue when the voltage regulator is starting to go. I haven't really ever tested this out on the 7800 though.

 

Mitch

 

Interesting...It's times like these I wish I had an even better understanding of electronics and electrical components.

 

A helpful piece of advice for developers who may have concerns about color/phase shifting is essentially whatever color you select on a 'technically accurate' palette, notice the color/shade just below it. Once the system is "warm" you may end up with the value just below the one selected regarding the mid-range (~4$ thru ~C$)

 

Essentially, the phase shifting that occurs ultimately ends up (on average) shifting much of the palette one "row" of values, or becomes a color somewhere between the current 'technical accurate' row and the one just below it. Obviously, from the captures and as can be seen in the latest created palettes, the impact is more emphasized and significant from the bottom (F$ -- E$ -- D$) and becomes less significant as you work your way up, to almost little to no impact on the top (0$ -- 1$ -- 2$).

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When I tried KevinMos3's color edit hack for Tank Command using my CC2 it wasn't the color he intended until my 7800 warmed up. After looking at this I'd guess he probably picked a color that was close to the edge of tan and green at the bottom because if I remember correctly it would start green but then later be the tan color he intended.

 

Exactly something I'm hoping developers/hackers and all to understand better. Thanks for sharing this. A safer/definite bet for tan staying in that region is 1$ (PAL = 2$); the row just below the grays/blacks stays consistent with minimal to no color shifting regardless of time passing.

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Additionally, and the other side of the green/brown/tan coin is if you want your green to stay green, stick with B$ and C$.

 

D$ may/does receive some change and E$ and F$ without question changes - and pretty dramatic at that.

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One other thing before I forget (again) to mention it.

 

Some may be thinking...

 

"Hey Trebor, I thought NTSC_A7800_FINAL is the non-bias default Atari 7800 palette using all the correct technical data. Why the heck then does NTSC_A7800_PHASE_25.7.pal and NTSC_A7800_FINAL not match?"

 

Two reasons, first these "PHASE" palettes have had their saturation bumped up by 50% to emphasize and be able to see the color changes more clearer and vivid...

 

"Hey Trebor, if these have a 50% bump, then why the heck doesn't NTSC_PHASE_25.7.pal match NTSC_A7800_FINAL_S.pal"?

 

...Due to the second reason why there's not an exact match...None of these "PHASE" palettes have been converted to YIQ. They are "RAW" values. It is a lot of work to convert even one palette to YIQ from scratch. Which I would have to do for each one since each palette has an entirely different phase value. Each one would be starting for scratch. And, if I am going to follow suit and not neglect PAL, they all would also have to be converted to YUV.

 

All together that would mean converting 18 palettes (2 are already done in the form of NTSC_A7800_FINAL_S & PAL_7800_FINAL_S), from RAW values to YIQ (NTSC) or YUV (PAL). I would love to be able to even do half of them, but honestly it is not going to happen.

 

Again, the "FINAL" palettes have the respective YIQ/YUV conversion in place, utilizing 25.7 phase shift (the documented and technically correct palette with no warm/cool system influence). In addition they also offer up various saturation and gamma values to help better meet the various CRT possibilities.

 

Just in case there is any confusion or misunderstanding, I hope this clears it up. :)

 

 

NTSC_A7800_PHASE_25-7: post-18-0-81902700-1363024148_thumb.png--(CONVERSION FROM RAW TO YIQ)-->post-18-0-76488700-1363024198_thumb.pngNTSC_A7800_FINAL_S

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What I do notice is the longer the 7800 is left on, the further the phase shift pulls the color palette on real hardware closer to the desired colors, as opposed to what most people have settled for as the "default" 7800 color scheme.

 

I'm going to have to respectfully disagree with you here as well. The "desired colors" I am presuming is your desire or an assumption on your part. I'm not exactly sure what palette you are referring to as what people have "settled for", and surely there has been some confusion of viewing the 7800 on a LCD/LED/Plasma as opposed to a CRT.

 

I 100% agree that there are many variations, but you need to start with a correct base palette in order to achieve possible variations, which we have accomplished and done with NTSC_A7800.pal and then its conversion to YIQ (aka The RAW palette as seen on a non-bias/traditional NTSC CRT), NTSC_A7800_YIQ.

 

Utilizing that YIQ palette as the base of the FINAL family set (NTSC_A7800_FINAL.pal), a slew of various gamma and saturation levels were provided. Traditional CRT's basically fall between ~2.35-2.55 gamma while a typical modern display is usually ~2.20, but can be as low as 1.8.

 

You gain even more benefits and options within MESS, as the correct base palette is in place with the most recent updates, and you can tweak: Contrast, Brightness, Gamma, Saturation, Tint/Hue, on top of adding all NTSC display 'features'. You spend enough time with it you can mimic your display near exact. If you output MESS to a CRT it will be a spitting image with the appropriate adjustments in place.

 

Anyway, here is the original NTSC library displayed at documented/technically correct settings - including phase shift of 25.7 degrees. If these are not your desired palette choice that's understandable, but the palette is perfectly fine with the real hardware staying and displaying within specifications (Keep in mind that the colors will be brighter when displayed full screen as opposed to smaller snapshots):

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How can you determine (relatively easily and cheaply) if your system phase shifts and to what extent?

 

Contrary to some opinion, a 7800 console that phase/color shifts when warm does not provide "intended" colors for games.

In fact, one very common game that suffers from phase/color shifting is Joust.

 

Here is a capture of all three enemy birds from the Arcade:

post-18-0-03292000-1366551305_thumb.png

 

 

Here is a factory exact phase/color shift example for those same birds on the 7800...

 

PHASE 25.7:

post-18-0-71194500-1366551301_thumb.pngpost-18-0-98011200-1366551729_thumb.png

 

 

Notice what happens to the enemy birds as phase or color shifting kicks in (By increments of 0.5 degrees)...

 

PHASE 26.2:

post-18-0-33514600-1366551302_thumb.pngpost-18-0-00187700-1366551731_thumb.png

 

 

PHASE 26.7:

post-18-0-31967000-1366551303_thumb.pngpost-18-0-99441600-1366551731_thumb.png

 

 

PHASE 27.2:

post-18-0-83250900-1366551303_thumb.pngpost-18-0-04158400-1366551733_thumb.png

 

 

PHASE 27.7:

post-18-0-31954500-1366551304_thumb.pngpost-18-0-03003000-1366551734_thumb.png

 

 

Utilizing a very common/cheap 7800 game (Joust) let the 7800 system run for a while. After about an hour or so come back and see what the enemy birds look like. If there is still the strong green wing/brown body contrast, you know your system is fine.

 

If you have a problematic system, depending on how much the wings of the enemy birds turn from green to brown will help you determine how much your system is color/phase shifting. In turn, it can help you determine how bad or good are the system’s capacitors (At least some of them).

 

Lastly… http://atariage.com/...at-do-you-want/

 

Color Shifts (Letters E & F)

Aged Capacitors (Letters J & K)

More/"Maria" Aged Capacitors (Letters O & Q)

 

The above 6 letter sets incorporate phase shifting for those interested in more variety with this issue.

The remainder of the palettes in the above linked thread is tuned to the correct and factory exact phase shift of 25.7.

 

As a really side/minor point this game looks like a good candidate for a relatively quick and easy (I presume) graphics hack. :)

 

The Pterodactyl could use tweaking, but definitely all the main birds in this game could be 'fine-tuned'. Off the bat, the wings are a little too short in the upward expansion respecting the height they obtain. Also, the body/neck length is too short.

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