Retro display solutions (monitors, TVs, CRTs, flatscreens, upscaling, calibration)

Discussion in 'Retro & Arcade' started by elvis, Jul 24, 2018.

  1. elvis

    elvis Old school old fool

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    The problem: old software and old systems were designed for old displays. Like all things, displays have moved on, and display technology has changed. This affects old computer and old console users alike. Issues that can arise from this in our retro hobby include

    * Display lag - delay between keyboard/mouse/joystick/gamepad input and action on screen
    * Mismatching inputs - new all-digital displays sometimes don't have the old analogue connectors used on retro systems
    * Ugly pictures - new displays have mismatching resolutions, or ugly artifacts when scaling old, low-res inputs. Sometimes the cables used on old consoles result in an image that has degraded quality.

    The solutions usually boil down to one (or a mix) of
    * Try to source an era-appropriate display
    * Choose a modern display with lower native lag
    * Turn off post-processing on your modern display (aka "game mode")
    * Try to "upscale" low resolutions with faster upscalers to reduce lag
    * Use better quality outputs from your devices
    * Use better shielded cables that don't introduce noise

    We'll go into specifics in the depths of this thread, but this first post will cover some basics about what we're aiming for and why.

    Displays

    Display technology varies greatly today, with LCD, LED, OLED, QLED and other emerging technologies for flat panel displays. Older displays for a long time tended to be CRT displays.

    The concepts of how a CRT work are fundamental to many assumptions of retro hardware. The super basics of a CRT (Cathode Ray Tube) are a cathode (hence the name) that generates electrons, and fires them as a beam (or ray - one per colour "channel" of Red, Green and Blue to make the visible colour spectrum) to the other end of a glass vacuum tube (the anode). Electro-magnets rapidly switch back and forth, deflecting the single, focused beam, drawing a single dot. The dot travels (relative to the viewer) left to right drawing horizontal lines, then resetting down one vertical step to draw the next horizontal line.

    How many vertical sweeps the CRT does per second to draw an entire frame gives us our frame rate, and ensuring the picture syncs to this timing gives us our vertical sync, or "vsync".

    CRTs could also do tricky things like draw half a frame (called a "field") in one pass drawing only the odd lines, and then draw the even lines in another pass. The downside was that the frame rate was halved (it required two fields to draw a complete frame), but the upside was an apparent doubling of the resolution. This mode was called an "interlaced" picture, which was great for video, but quite ugly for video games and computers.

    Different regions around the world had different electrical and resulting broadcast standards, which in turn dictated the resolutions and frames per second of video content for a long time (typically matching TV standards for a long time). Eventually technology progressed, and broke free from using electricity as the timing source. CRT soon technology improved allowing much higher resolutions. Additionally, LCD technology (especially LCD response) improved over time, and LCD became a viable alternative for drawing fast pictures to the screen.

    For more detail on how a CRT (especially an old one) works, this guide is excellent (sadly requires Flash to view, but still works in Chrome after allowing the addon to run):
    http://easymamecab.mameworld.info/html/monitor1.htm

    Resolutions

    There are an almost unlimited array of resolutions different computers, consoles and displays work on. For simplicity, let's consider three "eras":

    * Standard definition, or SD. Mostly 4:3 aspect ratio. For the sake of simplicity, we'll break these down to two regions, and VERY simple digital resolutions (the horizontal/X component being meaningless in analogue terms, where we only refer to the vertical/Y line count):

    - PAL (Australia, Europe)
    -- 384x288 pixels at 50Hz progressive ("288p")
    -- 768x576 pixels at 25Hz interlaced ("576i")

    - NTSC (USA, Canada, Japan)
    -- 320x240 pixels at 60Hz progressive ("240p")
    -- 640x480 pixels at 30Hz interlaced ("480i")

    * Enhanced Definition (ED) and VGA. Toward the end of this era we also began to have a mix of ratios, with 4:3 remaining, and 16:9 becoming common. This tended to give us standards like (and again, with analogue displays the horizontal value means little):

    - ED PAL 4:3 768x576 pixels at 50Hz progressive ("576p")
    - ED NTSC (sometimes called NTSC HQ) 4:3 640x480 pixels at 60Hz progressive ("480p")
    - VGA - identical to the mode above, 4:3 640x480 pixels at 60Hz progressive ("480p")

    Either non-square pixels were used, and the picture stretched to make the 16:9 mode (called "anamorphic"), or square pixels were used and resolution added to round numbers (1024x576, 852x480).

    * HD, Full HD, SVGA, XGA, and up. Modern resolutions we all know and love. In recent years moving into UHD, 4K, and even 8K.

    Connectors and cables.

    Older analogue cables/connectors/signals for SD content, worst to best in quality:

    * RF - Radio Frequency modulation, sent over antenna cables. This is how terrestrial broadcast video ("TV signals") used to be sent over the air waves to TVs. Many very old TVs only had RF in, and as such older consoles had a small RF modulator on the back to generate the same signals. They're extremely noisy, and the picture extremely blurry. Analogue RF broadcast was completely phased out in Australia by December 2013, but even so many new flat panel TVs still have analogue tuning capabilities in them.

    * CVBS (Composite Video Baseband Signal, or "composite") - Chroma (colour) and Luma (Brightness, also called "Y") with sync mashed into one cable, resulting in lots of interference and a blurry picture.

    * S-Video - Chroma (colour) and Luma (also called "Y") on separate cables/pins, sync on Luma. Noticeably better than CVBS, but still blurry.

    * YPbPr - also colloquially called "component" (an ambiguous term). Carries three separate signals, the "Y" is the Luma, the Pb and Pr are separate parts of the colour signals, and sync is on the Luma pin/cable. Theoretically identical to RGB, however in practice conversions back and forth can vary depending on internal system hardware. YPbPr can handle SD, ED and HD content generally up to 720p (progressive) or 1080i (interlaced).

    * RGB - typically for SD video and console game content, carried over 21pin connectors. The order of these connectors follow two common standards, "Euro" SCART, or Japanese "JP21". These send Red, Green and Blue on three separate pins/cables, and composite sync (horizontal and vertical sync combined into one signal) on a fourth pin/cable. For home computers, sometimes this signal can be sent over a DE-9 (sometimes incorrectly referred to as a "DB9") cable and often proprietary cables, sometimes with composite sync, sometimes separate horizontal and vertical sync. Considered the "best" standard for a CRT, mostly because it's native to how a CRT works with three coloured guns producing the full gamut of visible colour, and no conversion process required.

    For arcade machines there are a variety of connectors from JAMMA to many others, and at voltages that are higher than and dangerous for home video equipment.

    ED and HD analogue cables/connectors/signals

    * YPbPr ("component") - as above

    * RGB - typically sent over a DE-15 "VGA" cable and plug, with separate vertical and horizontal sync

    Digital cables/connectors/signals

    * DVI - Digital Video Interface. Comes in two common forms:
    - DVI-D - pure digital, no legacy analogue pins
    - DVI-I - contains the DVI digital pins, but also extra pins for Red, Green, Blue, HSync and VSync for analogue VGA passthrough

    * HDMI - identical digital signal to DVI, but can contain optional extra digital audio and ethernet signals

    * DisplayPort - a new standard that can pass through HDMI, dependent on manufacturer. More common in PC monitors than consumer TVs.

    Digital displays typically are designed for HD content, however by spec all can at the very least deal with ED/VGA resolutions (i.e.: 480p/576p/640x480) as a minimum.

    Some digital devices can occasionally deal with SD resolutions like 480i and 576i, however this is frequently a source of the problems we mentioned right at the top of this post - lag and picture ugliness. Very few deal with digital progressive scan SD content (240p/288p) well or even at all.

    That's the ultra basics. More to come...
     
    Last edited: Aug 20, 2018
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    elvis

    elvis Old school old fool

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    Choosing a good modern display

    If you're not using a CRT, a modern LCD or OLED display with low-lag is a must. Focus on reviews from sites that focus on lag as a testing option:

    * https://displaylag.com/display-database/

    * https://www.rtings.com/tv

    Upscalers for modern HD TVs, LCD/OLED TVs and computer monitors

    Upscalers, as the name suggests, scale resolutions up. Modern flat screen LCD/OLED TVs vary greatly in native upscaling. Some do a good job of upscaling 480p up to HD/UHD resolutions. A very small amount can handle 480i. Many do terrible things to 240p content (8 and 16 bit computers and consoles like the Commodore 64, Amiga, Master System, NES, Megadrive and SNES), assuming it's 480i, and making it look terrible.

    There are many video upscalers on the market. It's important to choose one that is known to be low lag, and work well with video game and computer content.

    The gold standard currently is the OSSC ("Open Source Scan Converter"):

    * http://junkerhq.net/xrgb/index.php?title=OSSC

    * http://retrogaming.hazard-city.de/ossc.html

    It requires YPbPr/Component, RGB/SCART, RGB/JP21 or VGA outputs from your devices as inputs to the unit. It can handle all sorts of weird SD and ED resolutions as inputs.

    From there it upscales VERY fast to DVI and HDMI outputs to a variety of digital HD resolutions.

    Downsides are it requires good quality outputs from your devices (RGB or VGA from computers, RGB/SCART or YPbPr/Component from consoles). Some older consoles require modding to get these outputs.

    It offers advanced options including scanlines to soften overly-sharp/bright images, and create a CRT-like effect.

    RetroTink-2X:

    A new player on the market from Mike Chi, inventor of the original RetroTink (an addon for the Raspberry Pi for good quality analogue output). The RetroTink-2X is a standalone (no RPi needed):
    http://www.retrotink.com/ (Scroll down past the first model to the 2X)

    It's a device that takes CVBS/Component, S-Video or YPbPr/Component SD resolutions only (240p, 288p, 480i, 576i) and "line doubles" them to progressive scan modes (480p/576p) over mini HDMI. Much simpler than the OSSC, but also much cheaper. Requires decent upscaling on your TV/monitor from 480p up to higher resolutions, so check your monitor/TV reviews.

    Downside is it DOES NOT support RGB from consoles or computers, but is a great option for certain systems where CVBS/Component or S-Video is the only default (non-modded) option.

    Both the OSSC and the RetroTink-2X can use new cheap HDMI-to-VGA "DAC"s (Digital to Analogue Converters - a small chip that translates pure digital signals to VGA or YPbPr signals with very low lag) appearing on sites like eBay and AliExpress to output to PC VGA monitors:



    XRGB Mini Framemeister

    * http://junkerhq.net/xrgb/index.php?title=XRGB-mini_FRAMEMEISTER

    * http://retrogaming.hazard-city.de/framemeister.html

    A Japanese device that was popular for years with gamers before the OSSC and RetroTink-2X turned up. Can be a bit difficult to find stock, but has great support for many older consoles and systems.

    GBS-8220

    A Chinese-made upscaler designed originally for arcade users, this is a simple, low-feature upscaler that takes RGBS (Red/Green/Blue/CompositeSync), RGBHV (Red/Green/Blue/HSync/Vsync), or YPbPr 240p signals (called "CGA rsoution" in arcade speak, different to the limited CGA colour space computer users talk about), and upscales them to 480p/576p, 640x480, 720p and 1080p resolutions via analogue VGA out. A great low-cost option where digital output isn't required, although greatly lacking in features and tweaks that make the OSSC better, and missing the image quality and pure speed of the RetroTink-2X. (There are community solutions and hacks for this, which we talk about below, but its still early days).

    Designed for arcades, it works equally as well for people using systems like Amiga computers or Sega Genesis/Megadrive consoles.

    * https://www.ebay.com.au/sch/i.html?_nkw=gbs-8220

    Note that certain models of these are known to produce a "noisy" picture. A very simple "mod" involving a strip of copper tape as an EMI shield (being careful not to short out any components) has been proven to fix almost all of these problems:





    Cheaper upscalers

    Generally not recommended if not something like the GBS-8220. These are often focused on video content where real time conversion is not a priority (e.g.: scaling VHS or DVD content, where as long as the video and audio are in sync, the overall delay/lag doesn't matter, unlike computers and consoles).

    Here's a comparison of the OSSC, Framemeister and a cheap scaler as a solution for taking SD RGB content from an Amiga and scaling it up for a flatscreen LCD monitor:



    And the standard excellent quality from the MLIG guys comparing a bunch of options

     
    Last edited: Jul 28, 2018
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    elvis

    elvis Old school old fool

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    Testing and calibrating (Short version, more detail later)

    Often even figuring out what's going on with your computer/console displays can be difficult.

    Computer users get a bit of a free pass here, being able to trivially generate and display test patterns of all sorts (a quick google of phrases like "CRT test pattern", "RGB test pattern", "Broadcast test pattern", etc will yield plenty of test images you can use to compare displays.

    Many original arcade boards will include a service mode with test patterns as well, and these often work in emulators like MAME by pressing either the "TAB" key to set a virtual dip-switch to set the board into test mode, or for newer games pressing the "F2" key to initiate the emulated board's software test mode.

    Console users, the 240p test suite was built to help you out here. It's a free/open-source project with ports to dozens of consoles that allows a number of tests for various colour outputs, brightness and contrast calibration, lag testing (requires some setup with a split output to two displays, but works well if you can swing it), and various effects like fast moving grids or rapid flashing on/off images used in old consoles to simulate transparency.

    If you have a flash cart, console modded forf homebrew, or emulator, download pre-built ROMs here:
    http://junkerhq.net/xrgb/index.php?title=240p_test_suite

    If you don't, occasionally sellers on eBay and AliExpress will offer working cartridges pre-flashed with the content. Make sure you aren't paying a premium for these, as the software itself is free, and you're just paying for the service and blank hardware it's flashed on:
    https://www.aliexpress.com/wholesale?SearchText=240p+test

     
    Last edited: Sep 12, 2018
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  4. Grant

    Grant Member

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    My understanding is that the default firmware does some internal interlacing and deinterlacng that causes some artifacts for moving objects.

    The video hardware will happily avoid doing this, so there are some projects to build an alternate firmware. However, I haven't seen anyone actually try to change the firmware on the board, the alternate "firmware" runs on an external device (the one I've used runs on a Raspberry Pi), wired into a pin header on the GBS, which overrides the on-board microcontroller and controls the video scaler chip directly.

    I haven't followed the progress on this, people have built override boards from smaller MCU devices like Arduinos. The main interest in this is on the Shmups forums, but I mainly followed it from Ian Stedman's (a hardware engineer in the Amiga community) posts on working with the scaler.

    Having a Pi boot up into Linux just to output some I2C commands is still a bit awkward for me, so I don't use my GBS board too much these days since I have better options. There may have been some good progress since I last checked.
     
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  5. power

    power Member

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    my 2c, i have a plasma and have found it to be very retro friendly. admittedly it is 10 years old this year.
     
  6. BuuBox

    BuuBox Member

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    Great thread. In composite's defence, you didn't mention RF modulators. :p

    I've found my recent Sony X7000D LCD TV handles the output from a component modified SNES well, where most LCDs don't handle the signal.
     
  7. OP
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    elvis

    elvis Old school old fool

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    deinterlacing, yes. (I'll try to post a bit more detail later for folks following this thread as to what that is, and the pros and cons). The output image certainly isn't as good as the OSSC or RetroTink2-X, which comes partly as a result of this (and the long data lines, which can be fixed with the copper tape mod I linked to above).

    There's a control method for microcontrollers called I2C (often written "I²C"), which is royalty-free, and a common way to control a lot of electronics (Old Apple iMacs with CRTs, for example, used I2C to control their output resolutions, which I annoyingly found out a while back).

    The RPi project sends I2C commands down the wire to push settings to the GBS-8220, and is documented here:
    https://shmups.system11.org/viewtopic.php?t=52172

    Think of it less like a firmware, and more like a remote control. However the end goal is to eventually build these functions directly into a flashable firmware for the device, however that isn't ready yet.

    The device by default doesn't have easy recall settings (favourites for different inputs), and also the deinterlace option can't be turned off. The I2C bus allows commands to be sent to turn on and off features that the manufacturers didn't bother putting in the menu. Other I2C control projects have been done by Arduino, but an RPi has an I2C interface and is easier to control when testing, hence why the developer of that project tested it out.

    I believe they've also added YPbPr encoding on the output (sent over the VGA plug on the device, so you'll need a cable to convert from ED-15 to RCA cables), which is useful for some newer TVs that don't include VGA inputs any more.

    If the noisy image was a problem for you, check the copper tape fix to see if that helps. But otherwise I think the "flashable" version of the project isn't there yet.

    It's not always the case, but certain old-model plasmas were noted for several features:

    * Good upscaling from 240p/480i sources
    * 4:3 resolution panels
    * Very little post-processing, which made them amazing for gaming

    LCD manufacturers all went a little silly on post-processing, and as a result did bad things for gamers. Thankfully their poor choices have been highlighted by many, and that's slowly changing.

    Ha, I totally forgot that last night. I'll add it in, cheers.
     
    Last edited: Jul 25, 2018
  8. OP
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    elvis

    elvis Old school old fool

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    So lots of text in this thread so far. Let's see some of it in action.

    Here's a kind YouTube user who's done a side-by-side comparison of the same console - a "1 chip SNES Jr", with the standard CVBS/Composite out on the left, and RGB on the right (the US SNES Jr 1-chip doesn't do video-level RGB out natively, so the console had to have a simple mod done to it to allow this - most PAL SNES consoles do RGB/SCART out natively).

    This was then upscaled by an XRGB-Mini (aka Framemeister), and captured by a HDMI capture card.

    Watch this one full screen and set the video resolution to the highest mode (only 720p60, but it's enough to see the difference). You'll clearly see things like wavy "noise" in the edges of the red text, an overall lack of colour saturation, and a lot of blur and ugliness in the left image compared to the right. This nicely highlights the importance of getting the best picture out of your old console first, before even considering the next steps of upscalers or display devices.



    Another, this time with Chrono Trigger, again highlighting the noise in CVBS/Composite.



    And for the Sega fans, Sonic on Megadrive:

     
    Last edited: Jul 25, 2018
  9. GumbyNoTalent

    GumbyNoTalent Member

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    https://www.iontank.com/projects/warhol-amiga
     
  10. power

    power Member

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    elvis

    elvis Old school old fool

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    Interesting in a way. The images themselves can be displayed on anything, really. They weren't specific programs that output images, but just content created (like a JPG or PNG file).

    It seems like this was more of an overall art piece where they wanted to simulate the visual appearance of the whole setup for a given look. The "internals replaced with solid-state hardware" sounds like a Raspberry Pi emulation setup to me. :)
     
  12. power

    power Member

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    I'd rather see them on a 1081 but understand why they've done what they've done.
     
  13. OP
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    elvis

    elvis Old school old fool

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    Yeah, it gets especially tricky if its a travelling thing. There was a mob doing the rounds a few years back called "Game On":

    https://en.wikipedia.org/wiki/Game_On_(exhibition)

    They travelled the world showing off their exhibit at different places (they even came to sleepy old Brisbane). It was a great setup, but they used a lot of LCDs and projectors in places, simply because lugging around large CRTs was just too hard when travelling country to country. Even some of their original hardware systems didn't survive the trips, and they frequently had to ask local retro enthusiast communities to help with repairs.
     
  14. GumbyNoTalent

    GumbyNoTalent Member

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    Sony G520 - 30kgs of goodness, was pita for lanage haulage.
     
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    elvis

    elvis Old school old fool

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    Modifying old hardware for new displays

    Sometimes physical modification of old hardware is required to make it more compatible either with upscaling devices, or new displays. Sometimes these modifications can be as simple as a specially designed high quality cable, and sometimes it requires extensive internal electronics work to modify or add components.

    It's impossible to list every single modification available, as not only are there so many variations, but there is constant new work being released almost daily from the retro hardware community. But here's a few sites and resources that might at least offer hints as to what steps may be required if you want to know more about your particular hardware. I'll avoid posting individual hardware retailers and modders, and instead post sites that aggregate information and news.

    If you have a specific system that you want to investigate mods for, please ask in this thread.

    * mmmonkey : loads of retro console mods, with a focus on both getting good quality video out of consoles, as well as region modding PAL consoles to play NTSC games:
    http://www.mmmonkey.co.uk/
    http://www.mmmonkey.co.uk/oldindex.htm

    * RetroRGB: Website and YouTube channel concentrating on getting the best quality output from your consoles for whatever displays you need (whether that's CRT or LCD). Covers a lot of new HDMI mods for retro consoles that are becoming popular
    http://retrorgb.com/
    https://www.youtube.com/user/RetroRGB/videos

    * My Life In Gaming - YouTube channel with a "RGB Master Class" series that covers the basic (100 series), intermediate (200 series) and advanced (300 series) of options, connectors, cables and mods for playing old systems on old and new displays:
    https://www.youtube.com/user/mylifeingaming/playlists

    * GameSX - written and maintained by a friend of mine here in Brisbane, the attached wiki was one of the earliest curated collections of hardware modification instructions ever to appear on the Internet:
    https://gamesx.com/
    https://gamesx.com/wiki/doku.php
    https://gamesx.com/wiki/doku.php?id=matrix
     
    Last edited: Jul 25, 2018
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  16. WuZMoT

    WuZMoT Member

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    I think a RetroTink-2X is on my shopping list now.

    EDIT: I'd like to see my life in gaming review one too...
     
    Last edited: Jul 25, 2018
  17. OP
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    elvis

    elvis Old school old fool

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    RetroRGB's latest interview with Mike has more videos of of in action. I'll dig it up when I'm near a real keyboard.
     
  18. WuZMoT

    WuZMoT Member

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    you mean this one?


    just watched it last night. Pretty much sold on this device!
     
  19. OP
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    elvis

    elvis Old school old fool

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    Yup, that's the one. Some good examples there of things like what CVBS/Composite vs S-Video from the same console looks like going through an upscaler to a digital display.

    My only gripe with the RetroTink-2X is the lack of RGB input, but there are a handful of converters around that can help out (it's another bit of research to make sure they're lag-free, though). Hopefully Mike will add it in future revisions of the unit.

    I bought myself one of these:
    http://www.ani-av.com/shop/product_info.php?products_id=220

    That connects my RGB-capable consoles to my large, 30" CRT with YPbPr inputs. Picture quality is as good as RGB, but no need to mod the TV. That same unit will work in the RetroTink-2X.
     
    Last edited: Jul 26, 2018
  20. OP
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    elvis

    elvis Old school old fool

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    Because I said I would:

     

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