Why was it possible to play NTSC PlayStation games in black & white on a PAL console & TV?

Question

When I was young I had a TV which only supported PAL. Also my PlayStation 1 was PAL. It had a mod chip. But some of my games were NTSC.

A PS1 game and also the console itself are always fixed to either PAL or NTSC:

Game CD showing "PAL"

Console bottom showing "PAL"

Why was it possible to play NTSC games in black & white (without colors) on my PAL console & TV?

I expected the console to reject NTSC games. Why does the PlayStation console have the text "PAL" on it if it also plays NTSC games?

Why did my PAL TV show the video in black & white if NTSC is a completely different video signal? I expected it to show nothing.

Later I bought a TV which supported PAL + NTSC and now all of my games were in color.

Answer 1

For the first question of why does a NTSC game disc can be started on a PAL console, there is no other explanation that the hardware is capable of running in both PAL and NTSC mode. So the game selects the video mode and the firmware does not prevent a PAL unit from running NTSC games, if it can even detect it's an NTSC or PAL game.

As you said that you had a mod chip, it bypasses the region checks, and thus the console runs the game even if it is meant for another region with different TV scanning system and different colour encoding.

Now, to the technical detail of why NTSC game can be played in a PAL TV as black an white, because it is certainly possible but depends on your TV.

There is a lot of misunderstanding regarding PAL, NTSC and SECAM, because they are not TV video scanning standards, they are strictly colour encoding methods applied on top a TV video scanning standard.

So while usually NTSC colour encoding is used in a 525-line 60 Hz TV system, and PAL colour encoding is used in a 625-line 50 Hz TV system, also 60 Hz PAL systems and 50 Hz NTSC systems have existed.

And old CRT TVs are not very sensitive to video signal timing, it is possible that same TVs electronics can be used with both TV scanning standards, but the only country specific parts would be the RF tuner and colour decoding modules for PAL, SECAM or NTSC.

This means that your PAL TV is perfectly capable of receiving and displaying both 50 Hz 625-line and 60 Hz 525-line video, but as it only has a PAL colour decoder, it can't decode NTSC colours, and will display the NTSC encoded signal as black&white. The colours would just be seen as a cross-hatch or checkerboard pattern of dots on the image.

Answer 2

The basic principles of TV are pretty similar around the world it's the details that differ.

An analog video signal splits the moving picture into fields, and each field is split into lines. The ends of the lines and ends of the fields are indicated by synchronisation pulses embedded in the signal.

Color TV is transmitted using a "subcarrier", the encoded color information is modulated, using QAM and then incorporated into the luminance signal as a high-frequency low-intensity signal. This can sometimes cause high-frequency patterns in an image to be mis-interpreted as color, or conversely cause high frequency patterns to appear in strongly colored parts of the image.

Demodulating QAM requires a reference carrier, also backwards compatibility was seen as important. To synchronise the demodulator and to indicate to the demodulator that it is receiving a color signal a "colorburst" signal consisting of the unmodulated color carrier is sent on each line outside the visible area of the screen. Since color TV was designed to be backwards compatiable, if the decoder cannot detect the correct reference signal it is designed to disable itself. This is why a poor TV signal will sometimes cause the image to flicker between color and monochrome.

Normally your console would refuse to run a NTSC game, but the mechanism used to prevent running bootleg games, is broadly the same mechanism used to enforce region restricitons. The mod chip bypasses the restrictions and allows any playstation game to try and run.

The game is still a NTSC game though, it will still assume it is running on a NTSC console. The result is likely to be something that is not a valid PAL video signal. Maybe it generates a proper NTSC signal. I think more likely it ends up generating some signal that is neither valid PAL not valid NTSC. Either way the color decoder in your TV says nuh-huh.

I have vauge memories that there were more advanced modchips, that would fix the color generation when playing out of region games. I don't know any more details though.

Answer 3

Many European CRT TV sets can sync to both a European-style 625-line 50 Hz video signal and an American-style 525-line 60 Hz (actually 60*1000/1001 ≈ 59.94 Hz) video signal. This capability started becoming common in the early 1990s. Most of them can only decode PAL color, though, which is why you can only view true NTSC composite (CVBS) or s-video (Y/C) signal in B&W.

The best workaround for the missing colors is simply using the RGB output of the game console or home computer (if it has one) and obtaining a compatible SCART-RGB cable. This will bypass the color decoder in the TV (as CRT TV color guns are inherently driven with RGB signal) and will also give you a much cleaner, higher-quality image. Most European CRT TV sets come standard with a multi-pin SCART (”Euro AV“) connector which accepts RGB signal with TV-standards-compatible (625/50, 525/60) timings.

Why was such 60 Hz capability built into the more modern European CRT TV sets if they generally still could not decode NTSC color?

Most likely because of the European (PAL) VHS VCRs, many of which were — also by the 1990s — capable of playing back video tapes recorded in the NTSC format and outputting the signal with the original 525-line 60 Hz timing but with PAL color (the so-called ”PAL-60” signal). Also, the European DVD players were capable of the same, although with those, too, you’d rather want to use the SCART-RGB signal for the highest quality.

People used this capability to watch home videos (video tapes) sent by their overseas relatives, and also to watch DVD movies imported from the USA and Japan. (Either DVD movies not yet released in Europe or DVDs of some niche type, such as anime shows straight from Japan.)

Commercially-published DVDs were often region-locked but the DVD players equally often had a “secret” remote code that could be used to access a hidden service menu where this restriction could be switched off, or the region changed to another one.

Also, imported or modded game consoles (such as yours) and dual-sync-capable, TV-compatible home computers, such as the Amiga, could make some good use of this dual-sync capability of the European TVs, along with the SCART-RGB capability of the same TVs.