VCS Quantum flux generated dolby digital 17.1 complient audio-video mod

[Dragnerok X]

Well not really that dramatic but the same idea.

 

Recently I've been looking over all of the '2600 video mods, looking over how they work, and deciding a verdict for my half-a-dozen-times-opened 4-switch.

 

I noticed the fact that the '2600 could generate seperate chroma and luma signals by combining a few pins together, generating up to a native s-video output. What I'm wondering is could there be/is there a way to go one step back, locate each part of the "chroma" seperately (i.e. in an RGB signal) and set the VCS up as a native component video (YPrPb) or RGB outputing device? Or am I just stuck at s-video and that's that?

Edited November 19, 2006 by Dragnerok X

[mos6507]

Well not really that dramatic but the same idea.

 

Recently I've been looking over all of the '2600 video mods, looking over how they work, and deciding a verdict for my half-a-dozen-times-opened 4-switch.

 

I noticed the fact that the '2600 could generate seperate chroma and luma signals by combining a few pins together, generating up to a native s-video output. What I'm wondering is could there be/is there a way to go one step back, locate each part of the "chroma" seperately (i.e. in an RGB signal) and set the VCS up as a native component video (YPrPb) or RGB outputing device? Or am I just stuck at s-video and that's that?

 

The VCS only generates S-video inside the chip itself. The same with the 5200/8-bit. The Astrocade actually has a native component output from the chip, but I don't think it's in the same format as today's component cables.

 

They now have inexpensive A/V switchboxes that will upconvert composite and S-video to component. I just don't know if they do any better job of it than a TV with an S-video or composite input. Converting after the fact is always worse than generating it that way to begin with.

[Bruce Tomlin]

The ColecoVision also has native component internally, which I think is the same as modern component. That's because it used the TMS9928. I've always wondered why Coleco ended up with that version of the chip, and I suspect that TI just had a bunch of them that nobody wanted and cut Coleco a sweet deal.

 

Still, the resolution on older consoles is so low that anything better than S-video is really just a waste of time.

[Dragnerok X]

Still, the resolution on older consoles is so low that anything better than S-video is really just a waste of time.

 

Yes, but I'd just thought i'd like to see how far Stella (the tia) could go.

[Uzumaki]

I think there is a detailed schematic of TIA somewhere, if you could get that and figure out the chroma part, you might be able to build a separate RGB version but I doubt it'd be of any use as seeing Atari 2600 has only 15 colors (plus white), each with 8 level of luma for a total of 128 colors/greys.

 

Stick with composite or S-Video, it's not going to get any better.

[Dragnerok X]

accidental double post, scroll down.

Edited November 20, 2006 by Dragnerok X

[Dragnerok X]

I think there is a detailed schematic of TIA somewhere, if you could get that and figure out the chroma part, you might be able to build a separate RGB version but I doubt it'd be of any use as seeing Atari 2600 has only 15 colors (plus white), each with 8 level of luma for a total of 128 colors/greys.

 

Stick with composite or S-Video, it's not going to get any better.

 

I realize the change won't be as dramatic as that from rf to composite or s-video, the change will still be there.

 

Take this s-video modded atari. Correct me if i'm wrong, but this is one of the best setups I have seen yet. This is where we are now.

 

 

...and here is a screen capture from the same game, pitfall, in stella. Now can you see a difference? The change may not be horrifyingly obvious, but it's there.

 

 

BTW - Thanks for the schematic idea, I'll see if I can look into it tonight.

[Dragnerok X]

Well, I looked at the schematics, and I got a less-than-ideal answer. However, to be fair, I got an answer. It turns out that, for some strange reason, because at the time there were no "video output standards" and they were using rf, atari made the "chroma" just a single pin on the tia. What does this mean? In order to get RGB output from the atari I will either need a chroma decoder or just get one of those "inexpensive a/v switchboxes" mos6507 described, which is more than likely a chroma decoder. That or I could ply open the tia and modify it, but that's rediculous. What does everyone else think? Any less-barbaric alternatives?

 

[LiQuiD iCe 9]

They now have inexpensive A/V switchboxes that will upconvert composite and S-video to component. I just don't know if they do any better job of it than a TV with an S-video or composite input. Convertingafter the fact is always worse than generating it that way to begin with.

 

they are upscalers they take the pixel count and add more pixles by filling holes with a guessed color between all the real colors. but 2600 is less than half of RDTV (thats alot of guessing and i think you may chance getting a blurring effect. they are for making an HDTV signal out of a RDTV signal and rgb is the one of the HD output formats so it'll split it. the fatal flaw is where there is that imperfections will be about 4 times bigger for the 2600 as well as the picture and more devices more degradation.

 

to make an s-video i think would be the same clarity as the RCA because the 2600 only has a 192x160 resolution. you will not be losing pixels anywhere in a lesser format but the plug maybe around longer than the RCA. i haven't done it but i'm 99%sure all you would have to do for the s-video is play with resistors on an rca circut and split them into one pin luminance+sync the other crominance (other two pins are grounds).

 

what video mod do you have?

i've been working on one that is like Ben Heckendorn's but i fixed the sony issue and i cleaned up the picture and color accuracy more, i just need some caps to finish it (actually i'd say its not like Ben's any more . there is about 2pixles of red or blue to the left of some colors, i think i need some different cap values.

you can see the lines next to the ladder and the trees i'm hoping to remove those. on most games the lines are not as noticeable but pitfall and pitfall 2 look the worst. but it maybe some internal noise or somthing

[Dragnerok X]

They now have inexpensive A/V switchboxes that will upconvert composite and S-video to component. I just don't know if they do any better job of it than a TV with an S-video or composite input. Convertingafter the fact is always worse than generating it that way to begin with.

 

they are upscalers they take the pixel count and add more pixles by filling holes with a guessed color between all the real colors. but 2600 is less than half of RDTV (thats alot of guessing and i think you may chance getting a blurring effect. they are for making an HDTV signal out of a RDTV signal and rgb is the one of the HD output formats so it'll split it. the fatal flaw is where there is that imperfections will be about 4 times bigger for the 2600 as well as the picture and more devices more degradation.

 

to make an s-video i think would be the same clarity as the RCA because the 2600 only has a 192x160 resolution. you will not be losing pixels anywhere in a lesser format but the plug maybe around longer than the RCA. i haven't done it but i'm 99%sure all you would have to do for the s-video is play with resistors on an rca circut and split them into one pin luminance+sync the other crominance (other two pins are grounds).

 

what video mod do you have?

i've been working on one that is like Ben Heckendorn's but i fixed the sony issue and i cleaned up the picture and color accuracy more, i just need some caps to finish it (actually i'd say its not like Ben's any more . there is about 2pixles of red or blue to the left of some colors, i think i need some different cap values.

you can see the lines next to the ladder and the trees i'm hoping to remove those. on most games the lines are not as noticeable but pitfall and pitfall 2 look the worst. but it maybe some internal noise or somthing

 

I haven't installed in any video mod yet, but I will either install 8bitdomain's board (because of the easy access to the chroma/luma signals and s-video capability) or do the "rgb option" I described earlier. What I'll probably end up doing, however, is install the 8bitdomain board in and then get the rgb from that, but that's just me.

 

With the lines you described only two things come to mind. For one, are you using ben's original mod or his newer one, because the newer one was supposed to bypass some un-necessary capacitators or something. My only other guess could be some form of rf interface, but how? I thought those mods were supposed to eliminate that?

[LiQuiD iCe 9]

i tried both of the mods. they both had shadows, lines, noise, and colors were off -though im sure it looks fine on a 5" screen but on the 24" tv i'd take the RF over them.

there is a transistor in the new one the goal was to boost signal. i found a way around that and you don't need a different circut for sony stuff. sony requires a louder signal so i lowered the resistance, tossed the transistor, and it looked the same through my sony vcr and my phillips tv. (well there is alittle more to it than that). you need about .75 volts to 1.5 on the rca video for a good picture. so i just put 1k pots on all the pins and added caps to clean it up. i'm so close i should order the parts tonight and get it over with.

 

i was supprised at how good it looked after looking at the alternatives here. i just hope i can get the lines out i'm abit of a perfectionist.

http://www.cheeptech.com/2600mods/2600mods.shtml#images

the lines are only there when certain colors are next to eachother so some games or parts of games are flawless.

the noise i was refering may be inside the stella but i don't know. i've tried cleaning the power but nothing changes so i doubt thats it. if i have to much capacitance on the any of the pins it slows part of the picture giving it a blurring or misaligned look. i've pretty much striped the signal mixing part of the board so i know nothing is interfearing over there.

here is an ugly pic.

 

the 8 bit mod i remember seeing that one then i couldn't find it for awhile. if i get that line out i think maybe i could design a circut to instal like that. but where is the fun? i haven't seen any screen shots of that one so until then i don't know if i would do it.

[Dragnerok X]

i tried both of the mods. they both had shadows, lines, noise, and colors were off -though im sure it looks fine on a 5" screen but on the 24" tv i'd take the RF over them.

there is a transistor in the new one the goal was to boost signal. i found a way around that and you don't need a different circut for sony stuff. sony requires a louder signal so i lowered the resistance, tossed the transistor, and it looked the same through my sony vcr and my phillips tv. (well there is alittle more to it than that). you need about .75 volts to 1.5 on the rca video for a good picture. so i just put 1k pots on all the pins and added caps to clean it up. i'm so close i should order the parts tonight and get it over with.

 

i was supprised at how good it looked after looking at the alternatives here. i just hope i can get the lines out i'm abit of a perfectionist.

http://www.cheeptech.com/2600mods/2600mods.shtml#images

the lines are only there when certain colors are next to eachother so some games or parts of games are flawless.

the noise i was refering may be inside the stella but i don't know. i've tried cleaning the power but nothing changes so i doubt thats it. if i have to much capacitance on the any of the pins it slows part of the picture giving it a blurring or misaligned look. i've pretty much striped the signal mixing part of the board so i know nothing is interfearing over there.

here is an ugly pic.

 

the 8 bit mod i remember seeing that one then i couldn't find it for awhile. if i get that line out i think maybe i could design a circut to instal like that. but where is the fun? i haven't seen any screen shots of that one so until then i don't know if i would do it.

 

By the way:

 

8bitdomain mod:Here

 

mod in action: see above pic of t.v.

[+remowilliams]

By the way:

 

8bitdomain mod:Here

 

mod in action: see above pic of t.v.

Note that that pic above (my sony plasma) is the 7800 video mod. Not sure which color settings the set was on when I took it either, there are several.

 

Anyhow, I've done two home made 2600 mods, two home made 7800 video mods, and one home made Colecovision mod - and all the 8bitdomain ones that I've got beat them all, and without screwing around with adjustments.

[Bruce Tomlin]

Well, I looked at the schematics, and I got a less-than-ideal answer. However, to be fair, I got an answer. It turns out that, for some strange reason, because at the time there were no "video output standards" and they were using rf, atari made the "chroma" just a single pin on the tia. What does this mean?

NTSC chroma is a phase-modulated 3.58MHz signal. Different parts of the phase correspond to different colors. S-video just puts it on a different line to allow a higher frequency (aka higher resolution) luma signal.

 

The 2600 simply put out a phase-delayed pulse for the color. The Apple II also used a similar method.

 

See, the reason you can't get RGB is that there isn't a red, green, or blue signal anywhere. Just an ugly phase-delayed pulse. You can decode the chroma into something that would be more precise, but that's like blindly adding a couple of zeros to a number to make it more "accurate". If you change 1 into 1.000, it isn't suddenly a thousand times more precise, because there was no way to start with a number that would be 1.005 or 1.234.

[LiQuiD iCe 9]

i thought that looked really clean. thats why i asked what mod you had. now it all makes sence . i think i'll still finish mine just to see if it gets better. this project inspired me to learn more about electricity and see the world in a new light. i just stayed intrested because it was the 2600 but now i've found other uses for my new found knowledge like fixing my POS sony dvd player again .

 

i might take the time (over the next year) to make a new smaller pcb for the 2600 with my mod in it (of course if it works out well) i know you can still get the old IC's for 2600 and those things are durable. i think a new board with precision parts wouldn't cost much and would last a good 100 years . maybe that rgb thing would be a step in the right direction. this all depends on my free time so it may never happen. its much easier to get a FB2 and cart mod that might not last as long and still doesn't have RGB.

 

NTSC chroma is a phase-modulated 3.58MHz signal. Different parts of the phase correspond to different colors. S-video just puts it on a different line to allow a higher frequency (aka higher resolution) luma signal.

 

The 2600 simply put out a phase-delayed pulse for the color. The Apple II also used a similar method.

 

See, the reason you can't get RGB is that there isn't a red, green, or blue signal anywhere. Just an ugly phase-delayed pulse. You can decode the chroma into something that would be more precise, but that's like blindly adding a couple of zeros to a number to make it more "accurate". If you change 1 into 1.000, it isn't suddenly a thousand times more precise, because there was no way to start with a number that would be 1.005 or 1.234.

 

i thought it was 3.57954 or 3.57957 i believe that the video quality will get worse if you run it through another devise it will not stay the same. (you should play the machine as it was orgionally coded for s-video pin #2 says it all.) because it will be digitally shredded and put back together in a new manner with the hope to be more accurate based on a quick anyalisis and a digital guess by a box that doesn't even know your name. its like amplifying music, digital doesn't make it better only more precisily limited and louder. every machine you put it through it happens again.

the big question is will you notice the decay, i'll bet not. but you'll be able to plug into the next gen tvs while that RF box is picking up someone's WIFI.

[Dragnerok X]

This is about when I wish monster (the cable brand) would make a chroma decoder...

 

[Dragnerok X]

...then again if there were a t.v. hook-up standard that required you to split the luma instead of the chroma we would be fine, if I remember right the atari has something like 3 luma pins!!!

[Zerosquare]

Why bother with RGB ?

 

1) since the 2600 isn't natively RGB, unless the TV's built-in S-video to RGB conversion is bad (unlikely) you won't get a better picture by doing the conversion yourself.

 

2) even if you figured out a way to get real RGB out of the video chip, all you would gain are slightly sharper pixel edges, since the output resolution is low enough not to be limited by S-video bandwith.

[Dragnerok X]

Why bother with RGB ?

 

1) since the 2600 isn't natively RGB, unless the TV's built-in S-video to RGB conversion is bad (unlikely) you won't get a better picture by doing the conversion yourself.

 

2) even if you figured out a way to get real RGB out of the video chip, all you would gain are slightly sharper pixel edges, since the output resolution is low enough not to be limited by S-video bandwith.

 

see post #4

[Zerosquare]

see post #4

Yup, but see post #14 If I understood well, the only way to get real RGB out of the 2600 would be to create a custom TIA. While it's probably possible using a FPGA (I know very little about the 2600), that would be a lot of work for little gain... Edited November 22, 2006 by Zerosquare

[Dragnerok X]

Yup, but see post #14 If I understood well, the only way to get real RGB out of the 2600 would be to create a custom TIA. While it's probably possible using a FPGA (I know very little about the 2600), that would be a lot of work for little gain...

 

I don't plan on creating a custom tia, that would be rediculous. I'm trying to figure out the best way to do this without modifying the tia, anything outside of the tia is fair game, however. That is, unless of course you have detailed, fairly simple to follow, schematics of your proposed "rgb tia"?

Edited November 22, 2006 by Dragnerok X

[Zerosquare]

I don't plan on creating a custom tia, that would be rediculous. I'm trying to figure out the best way to do this without modifying the tia, anything outside of the tia is fair game, however. That is, unless of course you have detailed, fairly simple to follow, schematics of your proposed "rgb tia"?

The actual electrical schematic would be quite easy, but you'd have to use a PLD (programmable logic device) ; and converting the TIA schematic into a "program" (more precisely, HDL code) for the PLD is going to be a lot of work. You'd have to ask the resident 2600 experts on this forum for more detail.

 

And if I read the previous posts correctly, you can't get anything better than what you already have without getting "inside" the TIA.

[Dragnerok X]

The actual electrical schematic would be quite easy, but you'd have to use a PLD (programmable logic device) ; and converting the TIA schematic into a "program" (more precisely, HDL code) for the PLD is going to be a lot of work. You'd have to ask the resident 2600 experts on this forum for more detail. And if I read the previous posts correctly, you can't get anything better than what you already have without getting "inside" the TIA.

 

I'm perfectly fine with your idea, if of course you do it. I don't really have a spare PLD around right now nor the knowledge to use it, but I, however, do realize what your saying about needing to get into it. Here's the tia's schematics if you need them.

 

http://www.atariage.com/2600/archives/sche..._tia/index.html

[Dragnerok X]

The actual electrical schematic would be quite easy, but you'd have to use a PLD (programmable logic device) ; and converting the TIA schematic into a "program" (more precisely, HDL code) for the PLD is going to be a lot of work. You'd have to ask the resident 2600 experts on this forum for more detail. And if I read the previous posts correctly, you can't get anything better than what you already have without getting "inside" the TIA.

 

I'm perfectly fine with your idea, if of course you do it. I don't really have a spare PLD around right now nor the knowledge to use it, but I, however, do realize what your saying about needing to get into it. Here's the tia's schematics if you need them.

 

http://www.atariage.com/2600/archives/sche..._tia/index.html

 

I am also open to chroma decoders and the like. The only time I've actually seen one used was here.

[Zerosquare]

I'm perfectly fine with your idea, if of course you do it.

Like I said before, I don't know much specifically about the 2600 -- I don't even own one -- your post just tickled my curiosity. There are some gurus here that know the hardware in details (Bruce Tomlin, supercat, CPUWIZ are the ones I can think of ; apologies to others, I don't read the 2600 forums often ). But what I can tell you is that it's not going to be easy, especially if you don't have prior experience with digital electronics and PLDs.

 

I am also open to chroma decoders and the like. The only time I've actually seen one used was here.

Sorry for repeating myself, but I doubt building a chroma decoder is going to make a difference ; you'll just be replicating what your TV already does internally (the guy in your link had to use a chroma decoder for his project, since the LCD only accepts RGB signals).