What a CRT is
A cathode-ray tube, or CRT, is the glass-tube technology used in most televisions and computer monitors until flat panels replaced them. Inside, an electron beam sweeps across the back of the screen, lighting a coating of tiny phosphor dots. The beam draws the picture line by line, from top to bottom, many times each second. Your eye blends these into a moving image.
This is a very different process from a modern flat-panel display, which holds a fixed grid of pixels and updates them electronically. That difference is the root of most of what follows.
Games made for the tube
Early home consoles and computers were built around the television sets people already owned. Hardware designers tied the console’s picture output directly to how a CRT drew the screen, and game programmers often used that to their advantage.
Several features of the old picture were baked into the design:
- Low, fixed resolutions. Consoles output a small number of lines, and the picture was meant to fill a screen with soft edges, not to show crisp individual squares.
- Scanlines. Because the beam draws lines with slight gaps between them, the image has a visible line structure, especially on lower resolutions.
- Blending. The soft edges of a CRT’s dots, and the way signals were carried, let colours bleed into each other. Artists often used this deliberately.
- Fast, direct drawing. The picture is drawn as the signal arrives, so there is no waiting for a processing stage inside the screen.
How artists used the limits
Pixel artists often worked knowing how a television would smooth their drawings. A common example is dithering, in which two colours are placed in a checkerboard or other pattern so that the display blends them into an in-between shade. On a CRT the pattern can look like a smooth gradient or a semi-transparent effect; on a sharp modern screen the individual pattern can be clearly visible.
Similarly, certain connection types, such as composite video, tended to mix colours at sharp transitions. Some developers used this behaviour to get more colours or effects than the hardware nominally offered. Whether a particular game did so depends on the title and platform, and the effect varied between televisions, so there was never a single “correct” look.
Because of this, a picture that seems blocky and harsh today may have looked softer and more natural when it was made. This is one reason fans argue about how classic games are “supposed” to look. A fair summary is that the original developers saw their work on CRTs, but the CRTs themselves varied in sharpness, size, colour and settings.
Light guns and timing
Some games relied on the CRT in a more direct way. Classic light-gun games used the way the screen was drawn: when the player pulled the trigger, the system briefly changed the picture, and a sensor in the gun detected the light at a particular moment. Because the image was drawn line by line with predictable timing, the system could work out where the gun was pointed. Many flat panels do not work that way. They may process and delay the image, and some do not produce light in the same pattern, so these guns often fail to work on them.
Timing matters in other ways too. A CRT shows the picture almost the instant the console sends it. Many modern televisions add processing that causes a delay, which players notice as input latency. For games that demand tight timing, that extra delay can change how the game feels.
What happens on modern displays
When an old console is connected to a flat panel, several things can change:
- The picture must be converted. The old signal has to be turned into something the new screen understands. Some televisions do this well; others add blur, delay or visual artefacts.
- Scaling. The old resolution is enlarged to fill a high screen resolution. If the enlargement is uneven, edges may look jagged or smeared. Image upscaling methods that keep edges clean tend to look sharper but also reveal details the original softened.
- Lost blending. Effects that relied on the CRT mixing colours may disappear.
- Different brightness and motion. Flat panels hold each frame on screen until the next one, which can make motion look different from the brief flash of a CRT.
None of this makes the game unplayable. Many people enjoy classic games on modern screens, and plenty of modern pixel-art games are designed for sharp displays from the start.
Ways players deal with it
People take different approaches, depending on their goals and budget:
- Using an original CRT. This is the most direct approach, though the sets are heavy, ageing and not always easy to find or repair.
- Using external scalers. Devices exist that convert old signals for modern displays with less delay and better image quality than a typical television’s own processing.
- Using filters in software. Emulators often include options that imitate scanlines and the glow of a tube. These are approximations. How close they get depends on the filter and the display, and opinions about them are divided.
- Choosing a display with low delay. Some modern screens offer a game mode that reduces processing.
Whether any of these is worth the effort depends on how much the person cares about the original look, and there is no single right answer.
Why this matters
The CRT story is a reminder that a game is a combination of software and the way it was displayed. Preserving only the code can lose part of the experience. This is one of the less obvious issues in why old games are hard to preserve, and a reason that some archives collect displays and not just consoles. It also shows why a 20-year-old game can look strikingly different on two setups without anything being wrong with either.