Gaming on a CRT

crt Shooting three electron beams through a vaccum at a phosphor screen at around 10⁷ m/s and deflecting them with powerful magnets while they produce a small amount of X-rays as a side product. Sounds like science-fiction, but that was the way we played games back in the era of 15kHz consoles. And don't worry, the X-rays only have low energy and are filtered by the case.

Standard CRTs could only display an analogue 240p or 480i signal. Aside from the low resolution there were also problems with the geometry, that can make it hard to go back if you're used to perfectly straight lines on an LCD display. But back in the '90s that was how videos and video games looked like and you didn't even notice it, because you were too focused on the games. The games appeared very smooth, because most of the 2D games ran at 60fps as opposed to the 30fps you get with most games on modern consoles like the PS4.

One of the huge advantages of simple CRTs is that there is no delay added to the picture. You press a button, Mario jumps. Easy as that. The only delay you would get was the time it took the electron rays to reach the bottom of the screen, but that was only 16ms on a 60Hz TV. If you live in Europe you might remember that CRTs only ran at 50Hz here, but to compensate that at a slightly higher resolution. Most PAL games didn't make use of the extra resolution and displayed black bars on the top and bottom. To make it worse, many games were simply slowed down from 60fps to 50fps, often even with lower pitched music. Playing PAL games was, and still is a torture, especially because basically all PAL TVs could also display 60Hz without problems. But if you have access to proper 60Hz NTSC consoles then gaming on a CRT can be amazing.


Composite

composite If you got your brand new NES or SNES back in the day you had to figure out how to connect it to the TV. The normal TV programs reached your screen through a simple coax cable that transports both the video and audio mixed together. That also works for consoles! If you connect the RF output of your console to a coax adapter or switch you could play your games by tuning into channel 3, 4 or 89 in my case. But because all the information is transported in one wire the quality was as low as it could get.

A simple upgrade to RF is composite, which is still the most common method to connect retro consoles. Composite uses three cables with RCA connectors. One cable for the video (yellow plug) and one cable for each of the audio channels (white and red for stereo). This improved the quality quite a bit and gets rid of most ghosting and audio hum. To get acceptable quality out of a composite signal you need a 3D comb filter. If there is only a cheap filter in your TV or capture device you will get moving distortions on the sides of objects. But even with the best display it will still look blurry and the colors are slightly off. Some developers took this into account and changed the colors of the game so that they would come out correctly on the composite video. There is also a bunch of games that use the blurring effect to their advantage. Overall composite is not a bad way to play retro games, but since there are better options readily available it shouldn't be used.

S-Video

s-video S-Video is a further improvement over composite. The image signal is transported over two wires, one for the black and white image and one for the color information. It is sometimes also called Y/C. Y is the luma signal which carries the brightness and sync information and C is the chroma signal which carries both the hue and color saturation. The result is a sharper picture with more accurate colors, but there is still some color bleeding.

As a European gamer you will probably never have used S-Video, but in America and Japan it was quite common. Some PAL TVs will support S-Video with an adapter on one of their SCART inputs, so check your manual if you want to use it.

RGB

rgb Instead of S-Video Europe got glorious RGB SCART which combines high quality video and audio into a single plug. The 21 pin SCART plug used for RGB video can also be used to transfer composite and S-Video signals, so make sure that you buy a SCART cable that is actually wired for RGB. An adapter with three RCA inputs won't magically transform composite video into RGB. RGB uses 4 wires to transfer the three main colors red, green and blue and also the sync information seperately. The sync information tells your TV where a frame starts and ends and is needed to display the video. Usually composite video is used as the sync signal (called sync on composite) since it carries both the video and sync information. In case of RGB, your TV will use the color information from the RGB lines and take only the sync information from the composite video. There are also cables that transmit the sync information without the video part of composite. This type of sync is called composite sync since it combines horizontal and vertical sync, but don't confuse it with composite video. It is sometimes also referred to as clean sync.

The resulting image is as sharp as it gets and the colors are as close to the original as your monitor can handle. Using RGB could respark your love for CRTs. If you want to capture your games or play on a bigger LCD you should definitely invest in RGB cables. If you've got a PAL TV that displays NTSC consoles in black and white you can use RGB cables to get a picture with the correct colors.

RGB video may sound similar to component (or YPbPr), but it is not the same. Like S-Video Component separates the luma information (b/w image + sync) and chroma (color) information, but in the case of component it uses two cables for the color information. If you have a CRT TV that has a component input you can get an active RGB to component converter and not lose much of the quality. Professional monitors like the Sony PVM and BVM series use BNC plugs for their RGB input, but the signal is the same. If you're using such a monitor you can get a simple adapter with a female SCART input and BNC outputs. Some professional monitors require composite sync and will not work with composite video as sync. For these you will either need a cable that takes (clean) composite sync from the console, or an active adapter that strips the video information from the composite signal. RGB on retro consoles is usually limited to 240p and 480i, but with more modern cable standards like VGA and DVI you can also transfer HD videos with analogue RGB. The RGB color system is also used digitally in HDMI, DisplayPort and basically every monitor in existence.

RGB Output on Retro Consoles

Most retro consoles support RGB output out of the box. Examples for this are the Super Nintendo, SEGA Genesis and Saturn and the Playstation 1 & 2. Other systems like the N64 or PC Engine can output RGB with a very simple mod and there are also more extensive RGB mods for consoles like the NES. Also many modern consoles like the Nintendo Wii or the PS3 support RGB SCART, but for these consoles you should stick with HDMI or component cables since you can get 480p or higher resolutions only with these cables.

You can find more information about specific consoles on RetroRGB.com.

SCART

SCART was the standard connection type you would find on a PAL CRT TV and most modern LCD TVs in Europe still have a SCART input. It was so common that even TVs without seperate composite jacks had one or two SCART inputs. SCART cables can transport composite video, S-Video, RGB and audio. Composite was accepted on basically all SCART inputs, but RGB was often only available on one of the SCART inputs. Higher end TVs also supported S-Video on one of their SCART inputs, often the one that didn't support RGB. The SCART plug is a lot bigger than the other plugs, but this comes with the benefit that you don't need additional cables for audio. Another advantage of SCART is that the plug is spacy enough to house additional components like resistors, capacitors or even small circuitry.

There is also a lot of AV equipment that uses the SCART connector, so you shouldn't have problem finding a switch for all of your consoles. There are even projects by forum users to create and sell new SCART switches like the gscartsw RGB-SCART project.

A standard called RGB21ピン (RGB 21-pin) was used in Japan. It is physically identically to a SCART cable and also transfers RGB signals, but the pin connections differ. Besides video information there are also power lines in a SCART cable that carry up to 12V. If you accidentally plug a SCART cable into an RGB21 socket you might fry the input within seconds. Basically all cables you can buy are SCART cables, even RGB cables for Japanese NTSC systems. In most cases you will only come into contact with RGB21 if you import an upscaler unit from Micomsoft's XRGB line of products. It is also often called JP21.

Cable Quality

Cable quality is very important for analogue signals. A cheap cable will cause an annoying hum and a range of picture problems. Checkerboard patterns are very common with cheap cables, but also cables that look decent might have problems with solid colors and will add some noise to the picture. Aside from official cables from Nintendo and Sony there are a range of well respected modders that will hand craft cables of high quality for a very reasonable price. Some people swear on RGB cables with clean sync, but in my experience there is no quality difference between a well made cable with composite video as sync and composite sync. However there might well be cases in which a cable with clean sync performs better.

One seller that is highly regarded is retro_console_accessories on eBay. If you're an active member of the German community Circuit-Board you should look for Kurzschluss_480Volt's cables. I use them for my Nintendo consoles and the quality is excellent.

CRTs

crt How do Cathode Ray Tubes actually work? As I already described in the teaser the technology behind CRTs is really interesting and if you're interested in physics you should check it out in detail. But let's focus on the basics here.

CRTs use three beams that scan the front screen from the top left to the bottom right in horizontal lines. Each beam corresponds to one of the primary colors and lights up small spots when it hits the screen. In contrast to modern monitors there is no horizontal resolution. While you may know that 1080p (normally) means 1920 x 1080 pixels, 240p on a CRT only means that there are 240 lines drawn on screen. On a standard LCD you have square pixels. On a CRT on the other hand the picture is squashed into a 4:3 resolution. For some systems like the SNES this means that the pixels are streached out horizontally. Some consoles (mostly arcade machines) used their supreme processing power to stuff more pixels into a line than you could fit on a screen with perfectly square pixels. Converting these non-square pixels to an LCD screen with square pixels is a challenge, but more about that later.

Another basic you should know about is the difference between 240p and 480i. 480i means that your TV is displaying an interlaced video with 480 lines, but at each screen refresh only half of the lines are drawn. The lines of the last refresh are still glowing on the screen and give the impression of a complete picture. The downside is that the picture jumps slightly up and down. If you want to display a 480i signal on an LCD you will run into interlacing artifacts, which show as ugly lines in motion scenes. Deinterlacing can get rid of them, but this step adds to the delay and usually lowers the sharpness. As you don't need any deinterlacing on a CRT it makes for a good display for 480i sources. The consoles of the PS2 and Gamecube generation used 480i on a SD CRT for most games with a few exceptions. Starting from that generation consoles also began to use 480p progressive mode which is the better choice for LCD displays, but cannot be displayed on a SD CRT.

The most interesting resolution for retro games is 240p. In this mode there are 240 lines on the screen that are refreshed around 60 times per second. Because CRT TVs are build for 480 line content there will be a darker line in between the 240 picture lines. These are usually called scanlines, even though techinally the colored lines are the actual scanlines. The example picture above shows a 240p signal. You can clearly see the red, green and blue sub pixels and the darker horizontal lines between them. The benefit of 240p is that the picture is rock solid and doesn't flicker like with 480i content. Basically all games on retro consoles from the NES to the N64 or Playstation use 240p as their main display mode. Although some 240p games switch to 480i for certain scenes. The technical difference between 240p and 480i is that the second field of a frame is delayed by half a line for 480i content.

Scanlines

emulated crt
Hover to remove CRT effect.

When you look at the CRT photos you will notice that there are dark horizontal lines, commonly called scanlines. They appear when a 240 line progressive signal is displayed on a CRT TV, in contrast to 480i material. These lines are not actually part of the game, that's why you won't see them on Nintendo's Virtual Console or other emulators by default. They also won't show if you connect your old console to an LCD TV. But scanlines are not just an artifact of an old display technology, they enhance the picture in a way that is not instantly clear.

Scanlines do not add any information to the picture, but by leaving every other line blank they trick your brain into adding information. The brain is trained to find patterns in everything we see. A round shape will look blocky in very low resolutions, but with missing parts between the pixel lines your brain connects the dots and makes it appear much smoother. Similarly, most objects that only consist of a few pixels look much more detailed with scanlines. They will also make color gradients look smoother than with just big blocky pixels. In addition to the scanlines, the overall softer image and color bleeding between pixel on a consumer CRT TV help with this effect. On top of that scanlines also help to mask some noise that might be in your video signal.

Dithering

Consoles that only had limited processing power or a limited color palette often used dithering to achieve transparency. This technique uses the fact that there is strong horizontal color bleed on a composite signal. By alternating pixels in a line it is possible to create a mix of the two colors. A waterfall as in Sonic the Hedgehog can be produced by alternating blue pixels with the pixels of the background. Dithering was most notably used in Sega Mega Drive games. By mixing two colors it was also possible to create colors that were missing in the color palette of the system.

dithering

The right image was blurred horizontally by 1px.

dithering zoom

Zoomed in part of the image.

There are various problems with this method though. The biggest problem being that it only works with composite cables and not the higher quality S-Video or RGB cables as they don't have the same amount of color bleed. To play games that use dithering on an LCD TV you have to simulate the horizontal blur. A few examples can be found on Retro-Sanctuary.

30Hz Drop Shadow

A big part of 2D retro games use drop shadows for transparency. With this technique a sprite is shown only for half of the frames. Because the picture alternates between showing a sprite and not showing it 60 times per second it appears as if the sprite is transparent. This effect also works on modern systems as long as the game is shown in full 60fps. When the game is displayed at only 30fps it will appear as if the sprite vanishes completely or as if it keeps its full opacity. This is a common problem with video platforms like Youtube that in the past only supported 30fps videos.

Overscan

CRT TVs had problems displaying an image on the sides of the screen, which results in a cut off part of the image. To accommodate for this, analogue signals have blank lines on the top and bottom of the screen and also black space on the sides. Some games gained a few milliseconds processing time by decreasing the vertical size of the picture. On a digital TV or captured image these overscan areas appear as a black border around the video. These borders are in addition to the black borders on the side that appear when a 4:3 image is displayed on a 16:9 screen.

Gaming on a Digital Flatscreen

crt Gaming on LCD flatscreens has become the standard for most gamers since the PS3 / Xbox 360 generation, as modern consoles and PCs offer high resolutions that demand a high definition panel. The benefits are obvious: flatscreens offer a big screen, brilliant colors, great contrast and dark blacks. There is also no high-pitched noise that plagued CRT TVs.

But there are also downsides. On most sets you will experience input lag. That means that a button press on the controller takes a while before you can see the action on the screen. This delay can be anywhere between 2ms compared to a CRT on a gaming monitor to 10ms on a fast TV, or even 30ms on an average TV. Most people won't notice this, but if you're used to instant reactions on CRT displays it might take a while to adjust. Still, the benefits outweight the problems.


HD Consoles and PCs

Modern consoles output 720p or 1080p at 59.94Hz. Many games on HD consoles are only rendered at 29.97fps, showing the same image for two frames, but there is an increasing number of games that once again are rendered at 60fps. Especially Nintendo focuses on a smooth framerate of 60 frames per second. Connecting modern consoles to your TV is a breeze, just plug in the HDMI cable and you're good to go. Don't forget to switch to the Game Mode on your TV though! HDMI receivers and surround speakers will immerse you further into the games by placing the sounds around you. On modern PCs you can also get higher resolutions like 1440p or 4K and framerates of 120 fps or higher with a monitor that supports high refresh rates, if you have the money to spend on one or more high end graphics cards. Steam's Big Picture mode has made it easier than ever to connect your PC to a TV, just like a console. It adds a console-like interface to your game library that can be controlled with a gamepad and has sufficiently big text that can be read from a distance. As with consoles, PCs can also output video and audio over a single HDMI cable.

Retro Consoles

240p lcd The biggest problem with LCD TVs is that they have problems with older consoles. Consoles that support 480p output over component will still deliver a reasonably good picture. 480i composite on the other hand will look extremely ugly, to the point where it's no fun to play. To make it worse, most TVs do not understand 240p and will mess up the picture with wrong (and unnecessary) deinterlacing, screen tearing and sometimes even outright no picture. The processing also adds a considerable amount of delay to the inputs which makes retro games feel sluggish on most LCDs.

Linedoublers, scalers and scanline generators

This is where linedoublers and scalers come into play. They are small (or sometimes big) boxes that will take the input from your console and convert it into something that your TV can handle better. The quality of these devices varies greatly. You can get a cheap box for under 50€ or you can spend over 300€ on a high-end model. I won't go into detail here, because Fudoh already wrote down everything you might want to know about them (and more!) on his website: Deinterlacing, Scaling, Processing: Classic videogame systems on LCD and Plasma screens

Besides scalers there are also scanline generators. If you just take a 240p image and double each line to get a 480p signal you won't get the same look of a CRT TV. To help improve the look of the games and hide some flaws in the analogue signal you can get a scanline generator to add fake scanlines to the picture. Some scalers will also have this feature included already. Again, if you want to know more about this visit Fudoh's website and spend some hours there.

Framemeister

framemeister The XRGB-mini Framemeister from Micomsoft is arguably the best scaler for 240p video games at the time of writing. At the price of around 350€ (incl shipping, taxes and accessories) it seems like a hard sell at first glance, but if your goal is to play retro games on a big TV it is absolutely worth the money. For capturing gameplay it is also the best option at the moment. But why is it so good? Unlike modern TVs and many other upscalers the Framemeister was actually developed for retro consoles and the engineers at Micomsoft understand the fine differences between 240p and 480i. It will take any input signal from composite up to RGB and output it at up to 1080p over HDMI. It also has the option to add scanlines to any of its inputs. The resulting picture is perfectly sharp and there are no problems when the game is in motion. If you don't like the sharp pixels you can use one of the many settings on the Framemeister to adjust the picture to your liking. There is one drawback though. The Framemeister adds a small delay to the signal, around 25ms. If you have a very slow TV this might be a problem, but even on an average TV with 30ms input lag it won't matter.

If you are sensitive to input lag you might find that the XRGB-3 is the better option for you. It can linedouble a signal to 480p using the VGA output in just 2ms.

All XRGB devices use RGB21 inputs. Never use them directly with a SCART cable.

To learn more about the Framemeister check out Fudoh's review. For a comparison between the different XRGB devices check Fudoh's Micomsoft Special. If you prefer a video you should check out My Life in Gaming on Youtube.