+mytek Posted February 10 Share Posted February 10 Hello this is my first post in the C64 area, but I have been a regular over in the Atari 8-Bit forums since 2015. So when a good friend of mine donated a C64 bread bin complete with 4 floppy drives I started discovering what this machine was all about. In that journey I began to notice a vertical white line that would be present on the left side of my LCD monitors, at least the ones that didn't cut off the over scan area. It looks very similar to this picture below which I copied from: https://videogameperfection.com/forums/topic/retrotink-2x-pro-commodore-64-white-line-left-hand-side-of-image/ This apparently is quite normal for the VIC-II chip, and from what I gather most users simply accept it as such. However since I have a background in eliminating over scan artifacts in the Atari 8-bit series computers, and created a small board called the UGV to both correct for this (eliminating what was never intended to be seen) as well as improve upon the overall video quality, I started a similar project for the C64. Over the next few days I'll be posting pictures and information about my progress with this new idea. 3 Quote Link to comment Share on other sites More sharing options...
+OLD CS1 Posted February 10 Share Posted February 10 Neat. I honestly cannot ever recall seeing this line on my 64s. Now I have to go look. Quote Link to comment Share on other sites More sharing options...
+mytek Posted February 10 Author Share Posted February 10 18 hours ago, OLD CS1 said: Neat. I honestly cannot ever recall seeing this line on my 64s. Now I have to go look. The monitor has to be capable of showing everything (e.g., most modern displays). On the original CRT displays, especially TV sets, the over scan literally wrapped around the edges of the picture tube, so were not visible. Then on many of the earlier LCDs they intentionally limited the over scan to mimic a CRT. However most modern HDTVs, computer monitors, and HDMI conversion devices show it all. Also in some of the earlier HDTVs they have a menu selection to allow over scan, with this usually defaulting to over scan disabled (although the naming of this can be confusing). RetroTink and OSSC will usually show it all no matter the HDTV in use. Besides the white line which may or may not be visible on a given monitor, there is also additional border area on the left side of the screen which can be seen in the normal boot-up Basic screen. This will give you a fatter left border than the right. Of course if the border is black you won't see this. What I'm working on will fix both issues. Quote Link to comment Share on other sites More sharing options...
Grimm1966 Posted February 12 Share Posted February 12 (edited) I'm very interested in your progress on this. I do know that the VIC-II Kawari board is able to remove this line, but that is a complete VIC-II replacement, so they have full control over the video output. https://accentual.com/vicii-kawari/ Edited February 12 by Grimm1966 1 Quote Link to comment Share on other sites More sharing options...
+mytek Posted February 13 Author Share Posted February 13 10 hours ago, Grimm1966 said: I'm very interested in your progress on this. I do know that the VIC-II Kawari board is able to remove this line, but that is a complete VIC-II replacement, so they have full control over the video output. https://accentual.com/vicii-kawari/ Yes I can very well see that if someone is re-engineering the VIC-II from scratch it would make sense to improve things at the same time, which apparently they have. Getting back to the stock VIC-II video output... So besides the white line that occurs directly after the color burst signal has ended, the left border begins not too long after that. The fundamental problem is that there should be a small space of approximately 1 microsecond resting at the Blank Level followed by 1 microsecond of the Black Level before any video data is to appear following the color burst signal. This 1 microsecond space is part is what's called the Backporch. Unfortunately there is an upward spike present in this area that's creating the white line. In the ideal video signal you should see something like this for timing when the computer is displaying a color bar chart. And if the Chroma signal wasn't present, then all that would be visible is the red dashed line representing different shades of gray via the Luma output, and there would be no color burst either. In a computer such as the C64 and the Atari 8-Bit, they both simplified the video output and made the Blanking Level simply the same as the Black Level, so you will not see that little stair step, thus looking very much like that 2nd image. I'll try to present some O-Scope pics in a few days when I get back into town that will better demonstrate the actual VIC-II video output with and without the VGATE circuit in play. Quote Link to comment Share on other sites More sharing options...
+SpiceWare Posted February 13 Share Posted February 13 Wild, never noticed that before and my Commodore days go back to 1980 when I was introduced to the PET at school, followed up with my VIC-20 in 1981 and my C=64 in 1983. Just checked on my C=128. Don't see it: But if I adjust the Vertical Position it shows up: Shows up even better in 64 mode: 2 Quote Link to comment Share on other sites More sharing options...
+mytek Posted February 14 Author Share Posted February 14 9 hours ago, SpiceWare said: Wild, never noticed that before and my Commodore days go back to 1980 when I was introduced to the PET at school, followed up with my VIC-20 in 1981 and my C=64 in 1983. Just checked on my C=128. Don't see it: It's mainly an LCD issue, and is something that usually isn't noticed on a CRT like the 1084 you are using, except when shifting the horizontal position as you did in the later photos. This is likely also why Commodore either didn't see it, or didn't feel it was a problem worth fixing in the VIC-II chip since LCDs weren't around during those times. 2 Quote Link to comment Share on other sites More sharing options...
+SpiceWare Posted February 14 Share Posted February 14 8 hours ago, mytek said: It's mainly an LCD issue, and is something that usually isn't noticed on a CRT like the 1084 you are using, except when shifting the horizontal position as you did in the later photos. This is likely also why Commodore either didn't see it, or didn't feel it was a problem worth fixing in the VIC-II chip since LCDs weren't around during those times. I've noticed similar issues with old TV shows, you'll sometimes see things at the edges of the picture that would not have been visible on a CRT, such as the black edges in Night Court along with the blueish stripe going down the left side. 2 Quote Link to comment Share on other sites More sharing options...
+mytek Posted February 18 Author Share Posted February 18 Tested prototype circuit... Final production version schematics can be gotten from HERE. I'm imagining this being done as a VIC-II piggyback board, with an optional modulator replacement board that carries a MiniDIN-4 S-Video jack and a 3.5mm Stereo headphone jack with the option to add a right channel audio signal from a 2nd SID if present, or jumper it for mono out on both channels. The plan would be to feed both the replacement modulator board jacks in parallel with the normal DIN-8 A/V jack signals so that either method would work in a singular fashion. Or the modulator replacement could be left out and just feed the DIN-8 A/V jack only via a short cable emanating from header J1. This completely replaces the stock video output circuits and produces a very high quality signal (even the composite looks great with no cross talk to disturb the S-Video signals). There are no unnecessary inductors or capacitors in the Luma and Chroma paths to cause color smearing or blurriness of the video image. Obviously the RF output will no longer exist. EDIT: Check out this blog post for even more info. 1 Quote Link to comment Share on other sites More sharing options...
+mytek Posted February 20 Author Share Posted February 20 A new post was added to my blog today going into detail about a rather major firmware change for the PIC VGATE chip. Instead of re-posting over here, it would be best to read that blog post instead to see the reason why this change got made. It's all good 👍 1 Quote Link to comment Share on other sites More sharing options...
Brentarian Posted February 20 Share Posted February 20 Michael, I have a PAL C64 I can lend you if you need it for testing. Just let me know and I'll ship it out this week. Quote Link to comment Share on other sites More sharing options...
+mytek Posted February 20 Author Share Posted February 20 Just now, Brentarian said: Michael, I have a PAL C64 I can lend you if you need it for testing. Just let me know and I'll ship it out this week. Hi Brent. Thanks for the offer, but I think it would be far cheaper and safer to just send you an assembled C64-VGATE board to test on your end. Shipping computers cross country gets expensive, and you always run the risk of something happening along the way. So you wanna be a beta tester for this? 1 Quote Link to comment Share on other sites More sharing options...
Brentarian Posted February 20 Share Posted February 20 Let me check tonight if I have an LCD that works with PAL. I've only used this one with a Sony PVM. 1 Quote Link to comment Share on other sites More sharing options...
+mytek Posted February 20 Author Share Posted February 20 3 hours ago, Brentarian said: Let me check tonight if I have an LCD that works with PAL. I've only used this one with a Sony PVM. I can also send you a cheapie HDMI converter that works for me, and I believe handles PAL as well. This way you can just use your HDTV. RetroTink would also work for this - do you have one of those? Quote Link to comment Share on other sites More sharing options...
Brentarian Posted February 20 Share Posted February 20 (edited) 1 hour ago, mytek said: RetroTink would also work for this - do you have one of those? I just ordered one. I've been meaning to buy one for a few years and figured this is a good time as any to do so. I'm not as adept with C64 as I am with Atari, but I'm learning. Edited February 20 by Brentarian Quote Link to comment Share on other sites More sharing options...
+mytek Posted February 20 Author Share Posted February 20 4 hours ago, Brentarian said: I'm not as adept with C64 as I am with Atari, but I'm learning. Same here. But I've never been one to simply use a retro computer as is, and always have to tinker with it. Of course tinkering brings knowledge. Quote Link to comment Share on other sites More sharing options...
+mytek Posted February 22 Author Share Posted February 22 After quite a bit of fiddling with my camera today, I was finally able to capture an image off my LCD monitor that actually looked like what I was seeing with my own two eyes. And let me say, it looks quite beautiful !!! Easy Flash 3 Menu via my C64-VGATE Video Board Prototype using the S-Video Connection Not bad at all for an analog video connection 👍 3 Quote Link to comment Share on other sites More sharing options...
+mytek Posted February 28 Author Share Posted February 28 PCB Layout for the Main Board has been Completed (also doubles as HMOS to NMOS VIC Adapter) This piggybacks the VIC-II chip, using one additional stacked machine pin socket underneath with pin-14 & pin-15 removed, and pin-13 removed if an HMOS VIC-II is to be used in a NMOS motherboard. This last option also requires solder bridging JP1 on the top to divert 5 V to pin-13 of the HMOS VIC-II chip. In this layout the component IDs have been locked in and changes have been carried over to the schematic (I'll be releasing the final version of that pretty soon). Header J1 and J2 will be right angle male pin type. J1 from left-to-right consists of GND, Chroma, Luma+Sync, and Composite which will feed the connector interface board that takes the place of the RF Modulator (that'll be my next task to complete). J2 is the ICSP for programming the VGATE PIC chip. The header is optional, and without it something like a pogo-pin adapter could be used for flashing the chip from the programmer. As in most of my designs I have retained as much THT type components as possible, and where SMD is concerned SOIC chips have been spec'ed which are the largest surface mount IC package available. All the caps are 0.2" pitch, and the resistors are 1/8 watt. 2 Quote Link to comment Share on other sites More sharing options...
+mytek Posted March 1 Author Share Posted March 1 Board set has been completed and schematics have now been released as first production revision level V1.0 on the AtariBits blog. Since I can't easily update said schematics here on AtariAge, they will only be made available as a download from my website. Here's a sneak peek at how the two board set connects together (Long Board Replacement RF Modulator Interface version shown). 2 Quote Link to comment Share on other sites More sharing options...
+mytek Posted March 5 Author Share Posted March 5 I picked up a C64C off of eBay with the Short 250469 motherboard so that I could have a newer test bed, and verify the changes required to make a specific RF Modulator Replacement Interface PCB for it, which is shorter than required for my 250407 bread bin motherboard. So here's what that'll look like. Same outputs and selections as the Long Board version. And I updated the schematics on my blog to reflect this additional board. 1 Quote Link to comment Share on other sites More sharing options...
+mytek Posted March 5 Author Share Posted March 5 I bit the bullet and placed a sample order for all the boards, as well as tossed in an order for some PLA replacements. Should have these in my hands in 5 days or less. The C64-VGATE Main Board is expensive due to it being 4-layer and the choice of a black solder mask. When it's 2-layer, any color can be selected without affecting the price, but anything other than green for a 4-layer board jacks up the price, but I really wanted black. EDIT: I think the biggest reason for the increased cost of the 4-layer board has to do with the thickness, which I spec'ed as 0.8mm instead of the normal 1.6mm. It requires the thinner board material to allow the machine pin socket for the VIC-II to stick through enough for easy soldering on the bottom side. If I had stuck with the standard green solder mask, even 0.8mm material costs would have been cheaper leading to a discount for my 4-layer order. I require a 4-layer board in an effort to greatly minimize any cross talk between the luma signal on the VIC-II and the clock and AEC pins. Essentially I use the "wrapped" shielding provided by all three GND planes to attempt to isolate the video signals from anything else. 2 Quote Link to comment Share on other sites More sharing options...
+mytek Posted March 19 Author Share Posted March 19 I got my boards from JLCPCB, and got one set built for my Long Board 250407 motherboard. I built it so that it could use an 8562R4 HMOS VIC-II chip instead of the original NMOS (it's fairly easy to configure it for this). Gives a nice picture on my 55" HDMI monitor using a cheap S-Video to HDMI converter. And does a good job outputting Composite video as well (that top to bottom gradient doesn't exist in reality, just a side effect of the camera). I used one of these to break-out the audio and composite video. White = Audio Red = Composite Video This is also configurable giving you a choice of signals on the right channel (red) output: Right channel Audio with Stereo SID, Mono to both channels, Composite video, or LumaCode (if you have the VIC-II-dizer). 3 Quote Link to comment Share on other sites More sharing options...
+mytek Posted May 3 Author Share Posted May 3 Short Board support has been tested and works, including PAL. More Info: https://ataribits.weebly.com/blog/c64-goodies-continued-part-7 2 Quote Link to comment Share on other sites More sharing options...
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