A major reason for differences in video quality between the R6 and the later chips is that the oldest chips output an integer number of chroma cycles per scan line, while the later versions output 227.5 cycles per line and--at least for the latest ones--263 lines per frame. This causes solid colors to appear as vertical stripes on the oldest chips, but as a checkerboard *whose phase alternates every frame* on newer ones. A modern LCD display will typically average together the chroma data from consecutive frames to yield a very sharp stationary image, but on a CRT there would be a slight shimmer. If you like I could write a little test program which should illustrate the difference nicely. Also, if you feed the composite output to a monochrome screen, the older chips will produce a really horrible black and white image when showing some color combinations.

@adriansdigitalbasement

4 жыл бұрын

Fascinating! Yes if you could create that test program and email it to me, I can show it in the next video. (See channel about page for email address.) Thanks!

@klaus-udokloppstedt6257

2 ай бұрын

finally I found an explanation for the very hard checker pattern when using S-Video with both of my C64s. one is a 250407 rev. B C64 with a PAL 6569R1 ceramic VIC and the other is a C64C (don't know board revision or VIC-type, as it was never opened, but it is not one of the very late versions, where the case is only clipped together). and obviously my TFT-TV does not average the signal of the odd and even lines. also interesting, that there is no checker pattern when using the SCART input, even that the Scart cable has the Luma and Chroma connected to the Video-IN pin (20) and the Red pin. probably the TV does combine both signals internally and then just uses it like a composite-IN. one more interesting thing: my other TV does not have an S-Video input. but it has a Component input (Y'PrPb). when connecting the Composite RCA to Y', it results in a B/W checker pattern display. thus the merged-in Chroma signal obviously effects TV's interpretation of the expected, pure Luma signal.

🙋There is no brown, just dark orange.

@nickwallette6201

4 жыл бұрын

[ pedantically smooth jazz ] :-D

@mrkitty777

4 жыл бұрын

Technology connections 😸

@daghtus

4 жыл бұрын

Guys can see 4-bit color palette only anyway. What the heck is United Nations Blue?

@mrkitty777

4 жыл бұрын

Don't understand Jan, technology connections is a KZread channel that published a deep video explaining that the color brown doesn't exist. Although we perceive it as if.

@frogz

4 жыл бұрын

@@mrkitty777 i think jan is trying to make a nerdy joke even nerdier by saying guys dont acknowledge certain colors, usually only allowing for 8-10 colors(if you include light and dark/black/white)

I love your videos! This is _exactly_ what I was looking for: Best possible video output on C64.

The best video explaining the video problems with a C64 I have ever seen. It is very clear, concise, and informative.

Now this is the type of mod I love learning about. Kudos on info and presentation.

Often (most times, in fact) I have no idea what you're talking about...but I enjoy hearing you explain it!

Awesome video, looking forward to what you found out with the modulator in part 2. Your videos on Commodore stuff are top notch and this is why your channel is my favorite lately. Keep up the good work. I still use my 1702 and 1084 monitors and that is what I prefer. Some of these issues aren't as noticeable on a CRT. But it would be a heck of a lot easier to use my flat panels instead. So this is perfect for that.

Thanks for putting in all the hard work on this video! Awesome to see the C64 shine on PQ!

Looking forward to part two

Awesome, always wanted to know how much I can possubly do to improve the video quality of the C64. Waiting on your next RF tweaking video. Awesome work Adrian! Cheers

Incredible, thanks for the great comparisons, looking forward to the fix!

Great video! Looking forward to part 2. Thank you

Thank you for your very sophisticated video about improving the picture quality of my c64 . I was about to get the luma fix, as for reducing the jail bars as I saw Jan Betas Video about this fix which looked very prokising. Now I leave everything as is and probably do the mods you will show in your next video.

That's a nifty little bypass board -- I haven't seen it before -- and the output clarity difference is amazing. Looking forward to your leave-the-modulator-in part 2 video.

Amazing, how many people still interested in the C64.

I have no retro gaming hardware but I just love watching you explaining stuffs. You would have been a great teacher.

I can't wait for part 2, very interesting topic. I am very curious as to how the bypass mod compares to the coveted 425 and 466 revisions

You're the true Dr. C64. :)

My wife got dressed up as a easter bunny girl ....she was on the left hand side ! and your youtube vid was on the right hand side .....guess what ...no easter eggs for me .....what another brill little vid ..... thx adrian ...darrell

video was beyond my technical knowledge but I still enjoyed. Thank you! Awesome channel btw 😍

Thank you, nece information! I look forward for part 2 :)

It’s amazing how much I learn from these videos. I pause and search google/wiki a lot but I am appreciating the hell out of these videos! I look forward to the RF modulator video.

I agree, i tried the Luma64Fix and couldn't tell it did much. I need to verify if it was on a NTSC or PAL board.. Look forward to part 2!

Adrian.. if I could hit two bell notifiers on your channel I would! Thanks again for being awesome..

Great now I don't have to do this comparison. Great video Adrian!

I'm looking forward to part Two . 2 Thumbs Up.

I would have to agree with Adrian on the LumaFix. I bought one back in the day and found the same - I just couldn't get it to actually look "better", only "different". About 6 years ago I removed my RF modulator and replaced it with a DIY veroboard amplifier with only the required pieces to run composite+chroma/luma, probably similar to that circuit that Adrian has. I replaced the RF output socket with a standard S-video socket so now makes it easier to plug it into an LCD monitor/TV. Pretty stoked with the result.

Very nice presentation and info, appreciate the efforts made to put this video together and tech info. I'm new to the channel and have subscribed 👍

On the older C64s with the 5pin video connector you can still get an s-video output. It has a luma output already and you can use the composite output for the chroma. The monitor will use only the chroma part of the signal. This might not be quite as good as if they were truly separate but it is better than composite only.

Fun extra fact about the 6567R56A: You say the screen looks wider. That's because it actually is. That revision has 64 cycles per line, while later NTSC versions have 65. One cycle is equal to one character cell, so that's why the viewable area seems wider. This also messes with some games and demos, that depend on exact cycle timing and expect the 65 cycles. (Side note: it's 63 cycles for the PAL version MOS 6569.)

@stevethepocket

4 жыл бұрын

Is that why the aspect ratio (well, the amount of space dedicated to the border) changes when I switch VICE from NTSC to PAL mode?

@slaur42

4 жыл бұрын

@@stevethepocket In part because of that, but the effect is minor. It makes the visible area slightly narrower in width, as compared to the border area. What affects it much more is that an NTSC video signal has 525 lines (and a field, shown at 60 Hz, has 262.5 lines) while PAL has 625 lines (and a field, at 50 Hz, of 312.5 lines). So a PAL screen has lots more lines that are used for the border area. Thus the NTSC visible area seems much taller on screen while showing the same 25 character cells / 200 pixels in the vertical direction.

Very informative video, many thanks!

Wow !!! Amazing difference ! Thanks !

Hey Adrian, I can not wait for part #2 which you will show how to improve the RF modulator. You do an awesome job and i like your videos very much. I want to do these RF modulator fix on my C128D-CR because the quality of the composite and s-vidoe signal is not very impressive. So keep on going ... Outstanding work ... "huch ist das aufregend" ... That is a german saying for "i am so exited" :) greets from the black forest of Germany

very informative video thank you

Love your Videos Adrian.

Cliffhanger! That white line you talk about is a good indication of a working VIC-II chip on an otherwise black screen machine.

@adriansdigitalbasement

4 жыл бұрын

Indeed! It will be there if there is a good clock signal and good power.

Love ye man! Keep up the great work!

Very nice. Hoping part II explains enough to allow me to mod my Pal C64 C modulator.

That tool that close to your LCD makes me anxious... Great video otherwise!

@mrkitty777

4 жыл бұрын

A cat with nails watching a mouse at TV scraping. 😮

@xdmkii

4 жыл бұрын

He actually hit the screen with it at least twice in the video.

@bitrot42

4 жыл бұрын

Me: TRIGGERED

Two parter? Now I have to wait!

Thanks for the good analysis :)

I can't wait for part 2! I've been cobbling together a VIC-20 from two not working ones, and I would love to crack open my C64's too to clean up the video quality.

@derdicky1982

4 жыл бұрын

Your c64 also lays in parts next to your soldering iron on your bench waiting for the next video? 😁

I already modded the output of one of my two C64 (SVideo mod) and now the picture is sharper but theres still a problem (checkerboard) so this is super interesting, thanks! Instant sub.

Thanks ADB !

One thumb up is not enough 👍🏻👍🏻👍🏻👍🏻👍🏻👍🏻👍🏻👍🏻👍🏻👍🏻👍🏻👍🏻👍🏻 I really appreciate your research on this. It is said, that the AEC and PHI2 couple in the luma signal on the VIC-II chip. But I don‘t necessarily believe it. The C64 board layout is way less than perfect and since those signals are everywhere on the board, they might couple everywhere else, too. I have experienced the LumaFix64, too. I think, it is not that bad. I have mainly used them on the short boards. Those are very sharp but also show the jail bars very sharp. The LumaFix64 removes those interferences pretty well. It also blurs the image a bit. I have to admit, that my old eyes don’t really notice that, when sitting in front of the 24“ tft monitor, that I am using. So I like the LumaFix64. But that might be different on NTSC machines. I unfortunately only have PAL C64s. I am really looking forward to your modulator fix. A lot!

That tool you were using as a pointer looked kind of like a little crowbar. Part of me was expecting a miniature Gordon Freeman to pop up at some point in the video. 😁

thanks. I'm looking forward to part 2 because my C64 has all these blurry characters on certain colors that i've been trying to fix for a long time.

Very interesting mods and comparisons, the best I've seen. I was wondering, does the RF shielding (that you often remove) make any difference?

@adriansdigitalbasement

4 жыл бұрын

Not that I saw no. I'll talk more about it in the next video.

Great job!

12:20 Hvetebolle? That's Norwegian and means wheat bun.

May I suggest to perform the same RF modulator mod we are going to see in the next video, for vic20 and 264 series? Rally interesting Adrian, as usual.

Despite the fact that it is next to impossible to find one of those machines here in Brazil and, when you do, it is prohibitively expensive, I *love* those simple digital designs and, been 53, I grew up watching those computers be born so if it's in your channels, I'll watch :)

Enjoyed it, thumbs up.

I'm running several Lumafixes in various machine (all PAL). For me, they work just fine.

@RetroRelixRestorer

4 жыл бұрын

EgonOlsen71 Yes, for me too; including a C128 one - which is absolutely perfect. 👍

@EgonOlsen71

4 жыл бұрын

@@RetroRelixRestorer Where did you get the C128 one from? I was looking for such a thing, because C128s suffer the most from this effect IMHO. But I couldn't find any.

@RetroRelixRestorer

4 жыл бұрын

EgonOlsen71 eBay seller ‘sharewa_56’ but they don’t seem to have any at the moment. Maybe worth asking?

@brianv2871

4 жыл бұрын

Yeah, I'm curious the models of c64. I tried the lumafix in my c64s (the ones with 8701 clock chip) and they didn't seem to do much for me.

@fossisoft

4 жыл бұрын

Yes, I can confirm this for my PAL C64, too. I rember that I had to turn the screws on the capacitors very often to the end to see the improvement. But if you had turn enough, it was great!

The 5 pin C64's can support a luma-chroma output. On the 5 pin connector there is a separate luminance pin (pin 1), and the composite signal (pin 4) can be used as the chroma for a slightly sharper/clearer output than just using composite by itself.

The 6567r56a also has some issues with certain games, I have a 250407 board that came originally with the ceramic 56a, when I loaded IK+, the spirites would glitch and flicker. I upgraded to a r9 and it works fine now.

Very nice! I'm looking forward to the next video. I'd like to optimize the video quality on my C128 (PAL), so I hope I can use your next video to do that. As far as I know, there is no rf modulator replacement for the C128. If there was, I would have jumped on that. :)

Ok, I am waiting now for three days. Can't wait for your big reveal: How can I fix that lousy Picture coming out of my C64 machines? - Keep up your great work. To me, your channel is the best, even if Jan Beta, Robin Harbron and Birt are right behind you ;-). Many greetings from Germany - and stay healthy!

I've actually had great results with the lumafix, on a 466-board with a rf-modulator replacement similar to the one in this video. But yeah it took some time getting the settings just right.

very much looking forward to the next part, I have a 64c which has ghosting issues, do you know if your fix will be applicable/adaptable to the modulator on these models? I have seen similar modulator replacements that will fix it but I'd rather keep RF and composite output

I'd be interested to see what the different raw chip outputs look like from an oscilloscope/spectrum analyser using a standard test pattern.

@benbaselet2026

4 жыл бұрын

That was immediately my thought also. A well-known selection of signals and scoping would help so much to see what is going on in the signal and tweaking things would be way easier when you can see what's going on.

a certain level of quirkiness is to be expected when using these older systems on newer screens, the atari has an even more concerning looking one thanks to a glitch in screen rendering

@alerey4363

4 жыл бұрын

yes, and if you go try to sharpen too much the signal on a modern LCD screen I guess it will look more like a VICE emulation and less than an analog CRT

RGB -> SCART FTW! At least on my Spectrum. Can’t believe it was not possible on a C64.

Thank you for this interesting video. I hooked up my C64 and my C116 to a beamer in my small gaming room. This video will help me to improve the picture quality. I've also thought about buying a scanline generator to imitate the look of my commodore 1084. It would be nice if you could also make a video on this subject. I think this could also be interesting for those of us using a modern tv as a monitor for there c64.

Hi Adrian, I love your video. I was wondering f if you did a video on correcting the C64-C video output? Thanks and keep on the good work.

I'm looking forward to the RF mod video.

The white bar on the left is because the circuit that does the screen blanking is one pixel ahead, so there is a window of time during which the display is not blanked out but there is no active color defined. In that case the chip outputs white. There is a defect in the chip where the blank signal is delayed a bit further so the bar is sometimes 1 and sometimes 2 pixels wide, depending on chip, or even things like temperature.

@Luthiart

4 жыл бұрын

I've noticed that.. On my C64, sometimes I get a stark, white line, and if I turn it off and on again, the line is often thinner and light blue in color (or at least appears light blue). I never knew why that was.

Having tried the Luma fix mod, was dissappointed. In the end, binned it.

Nice!

Looking forward to P2. My 250407 with 6567R8 connected to a Sony LCD TV has a terrible picture.

Thanks for the video. What causes the jail bars? Are they small wobbles in the output voltage maybe caused by a clock jitter? If the output is limited to set voltage levels, can the bars be removed by limiting the output to a predefined set of levels? It could probably be done a couple of different ways depending on cost. Just a side issue. On boards that I use to test things, I pick one of the logic chips near the centre of the board and put a flashing red led across the local filter cap. Too many times I've gone to swap parts on a board still powered up. At a dollar and at 5v, Kingbright type LEDs flash around twice a second. It can be done extremely neatly with short right angled legs.

nice video. Where is part 2? Thank you

I didn't know the video output was passed through they RF modulator. That really sucks, I would have put money on that you could rip those things out without issue. Will the upcoming fix for the RF moduator work on the C64C? it has a much smaller RF modulator, i assume it's quite different inside.

The video was particularly amusing to me because KZread refused to play it above 360p until I cleared my cache.

@rivards1

4 жыл бұрын

KZread defaulting to lower streaming rates now because the internet is getting overloaded with everyone at home.

I REALLY LOVE C64 👍🥂🎩

hello, great change! I, inside one of my C64s, have a 6567 r5 which produces a rather good signal even using an LCD TV. there are some really strange reviews of 6567 in terms of behavior.

@ Adrian's Digital Basement It should be noted that some people like and prefer the "soft" look rather than crisp, sharp pixels. There are two reasons for this. First, it looks more natural in the sense that no one exists as blocky sharp edged pixels, so games look "better" when the edges are blended together by the natural imperfections of the display tech. Second, the resolution of the C64(and all computers/games systems of the 80's & 90's) is too low for the pixels to gain much from sharpening of the image. Even 640x480 fails to gain much. 800x600 and beyond however gain much from sharpening because the pixels become smaller and not easily singled out by the human eye. I still think this is really interesting and look forward to the next video!

@adriansdigitalbasement

4 жыл бұрын

It is up to personal preference, but these machines filter the signal unnecessarily. The differences I showed are very obvious and apparent on a CRT. It is just not easy to film the screen of a CRT. So to properly illustrate the changes, the LCD was used. The filtering renders the C64 video bandwidth to less than it is possible to do. That is why Commodore fixed this issue in later boards.

@thecaptain2281

4 жыл бұрын

@@adriansdigitalbasement Good points all!

With the REV A board which lacks s-video out, you run the Composite into the Chroma input, and Luma to Luma on the 1702, and the display looks VERY NICE. Just turn the brightness down.

Check the 5V bus with your o-scope. If it's noisy, and it probably will be. Do an FFT and see if the frequency of the jailbars is in the spectrum on the power line. If so, consider using a separate Low Noise LM317 to provide cleaner power to the video circuitry. Amazing upgrade to the stock machine, hopefully your explorations and fixes are carried thru to new C-64 mother board options like the SixtyClone. Also enclosing the video amp board you have in an RF shield with magnetic chokes on key lines like power in might be helpful too. Great work, and thanks! Loved the sweep thru the hardware variable space.

@adriansdigitalbasement

4 жыл бұрын

That little board has ferrite beads on the inputs actually. The VICII 5v has its own 5v power from that 7805 from my understanding otherwise yeah, too much digital noise from other components.

@AndrewTubbiolo

4 жыл бұрын

@@adriansdigitalbasement Regulated power supplies have made great advances from the 1980's. I'd explore the 5v line from the VIC chip then, and if it's bad, replace it with something modern. Again, thanks!

Seems rather akin from going from Composite to RGB on an Amiga, though living here in SCART land makes it easier for people like me, so long as you can get a DB23F connector (mine came from a dead A520 modulator) for cheap of course, but completely different computer anyway, but the results are just as pleasing... :)

I find the blurry images gives that nostalgic look and also serves as a type of anti aliasing. When i first got into c64 emu's i was actually disappointed at how crisp the display was. Couldn't get that nostalgia i was hoping to get. Even the pal emulators don't quite cut it.

@benbaselet2026

4 жыл бұрын

Dude, just smear vaseline on your screen!

@millomweb

4 жыл бұрын

Just connect it to a CRT and defocus it just the amount you want :)

NTSC wasn't a hack, it was a conscious decision to maintain backwards compatibility with existing b&w sets on the market.

I built a few LumaFix boards, they are far more effective in the C64C (short board with the later VIC-II) than the breadbins.

I use luma output for B&W picture and I've noticed that it is super sharp (PC VGA like)for about 3 seconds after turning C64 on. After that it becomes more "comodorish" and I don't know why. I've also noticed that the picture heavyly depends on which PSU i use.

Tip. Lock your focus. It was rather distracting at then end. Likely the cameras auto focus picked up on you hand movement or something. Else a great video. Very interesting.

I wondered how much of this is a factor of the RF modulator - the chroma/luma goes into it, and comes out of it again to go to the DIN connector. Some C64s seem to run the modulator from unregulated 9V, and some run it from regulated and L-C filtered 5V. I suspect there is a buffer amp in the modulator, and this is a factor. It'd be interesting to take the chroma/luma straight out of the VIC-II, and feed it through a modern video buffer opamp, fed from the +5V line. The separate board Adrian shows seems interesting Has anyone tried adjusting the pot on the C64's that have the 74LS629/MC4044 clock gen circuit and see if that affects the picture?

@jaycee1980

4 жыл бұрын

You might also find there is some improvement to be had by using screened cable for the chroma-luma jump wires. Connect the screen to GND at one end only.

@jaycee1980

4 жыл бұрын

Another thought occurred to me about the RF modulator - it will have an oscillator in it (possibly two actually) which are potential sources of interference to get coupled into the video signal. So by removing the RF modulator, you're removing those oscillators. I suspect it's probably more to do with poor bandwidth of the amplifiers in the RF modulator though, coupled with the fact that some of the board revisions run the RF modulator from unregulated 9V supplies

The brown smearing on the C64 created a generation that loathed the color brown, while its greens were super sharp. The flickering of white backgrounds was unbearable, too, hence you might find generation X preferring green text on black backgrounds. Most of my C64's life was monochrome, however.

NTSC = Never Twice the Same Color

@jonasthemovie

4 жыл бұрын

Never The Same Color works better to me

@alsvith

4 жыл бұрын

PAL = Pay A Lot SECAM = System Essentially Contrary to American Method

Love this video! Makes me want to test out all my C64's but they're stored at my parents place and current lockdown rules here only allow travel for essentials. I doubt a policeman would understand my needs should I get pulled over. :-(

@brianv2871

4 жыл бұрын

You're going to your parents to bring them essentials and check on them... that's allowed.. and while you're there, you should pick up that computer 😁

@BertGrink

4 жыл бұрын

@@brianv2871 You, Sir, are a genius! :D

@klausstock8020

4 жыл бұрын

Don't tell the police about the Commodore 64. "What, Covid-64?"

Hello! Whats that pacman watch in you desktop????

I get Jail-Bars on my Amiga 600 to NEC 1970NXp

Adrian, if you're REALLY bored, you could come up with a fix to eliminate that left-side vertical bar :) (19:19)

I always thought that line was a fault with your LED monitor, my work bench LCD is an older 4:3 so I never see it (I also was lucky with that LCD because it can also display PAL :P )

Have you tested luma-only with the other chips? (I've read that later revision chips used 8 levels of luma, to allow for better differentiability between colors on B/W TVs compared to the 4 levels used on early revision chips)

@adriansdigitalbasement

4 жыл бұрын

As far as I know, this is on the PAL VIC-II chips. Indeed that first revision has only 4 levels compared to the 8 of later ones. The NTSC chips I have don't work this way.

I hate cliff hangers!!!! Interesting info.

Adrian, I've noticed that your camera has really aggressive auto-focus. It's especially noticeable at the beginning and end of your video when you're talking with your hands or leaning forward slightly. You can really see your face and background go in and out of focus because the camera is auto-focusing on your hand. Would you consider maybe locking your auto-focus when you're in front of the camera talking?

It is more accurate to say that NTSC is designed to encode color on top of an existing black and white television system. The proper name for the luma component of an analog television signal used in the US/Canada (among some others) is System M. NTSC is only technically used as the name for the color encoding standard (even though the organization it is named for also created System M).

Cool, man. I assume that you upcoming rf modulator hack will also work on a 128dcr?

@adriansdigitalbasement

4 жыл бұрын

Actually no. Commodore used different modulators on each system and it seems no one has schematics for them so I had to reverse engineer the ones on the 250407 boards by hand in order to know how to fix them.

@Lee_Adamson_OCF

4 жыл бұрын

@@adriansdigitalbasement Well phooey! I guess I'll have to reverse engineer mine too then. Almost makes me wish I was on a coronavacation so I had more time for that sort of thing, but unfortunately I appear to be "essential." :P What do you do, just cut power to the RF section somewhere to keep it from RFI-ing back into the signals, and leave the video amp thingy and combiner stuff alone?

@kevgardner3064

4 жыл бұрын

www.bit-c128.com/ or gglabs.us/node/2022

On my C64c the lumafix I got has now noticeable downside

What upscaler do you use to connect the c64 to your LCD? I've been having a hell of a time trying to get anything to work

@adriansdigitalbasement

4 жыл бұрын

RetroTink 2X