NTSC and PAL timing

[Lord-Chaos]

Could there be problems on ATARI 2600 NTSC machines if I write a game on a PAL system ?

 

I mean timing problems, missing scanlines , wrong colors.

 

What do I have to do , so that a game will work on both PAL and NTSC without problems ?

 

Do I need different color tables , since some NTSC games really look awful on PAL machines (blue gras in International Soccer , ugly!) ?

 

The problem is that I only have PAL machines and emulators , but no real NTSC machine.

 

And what about SECAM machines ?

 

Thimo

[EricBall]

The following things change between NTSC and PAL:

 

1. Number of lines on the screen: NTSC=192-208, PAL=228-240

 

There are several ways to handle this. Easiest is to code to NTSC screen size and just add blank lines to the top & bottom for PAL. Or you can make the playing area larger, or even try to rescale everything.

 

2. Refresh rate: NTSC=60 Hz, PAL=50Hz

 

Depending on your game this can effect a lot of things. Period (counter to wait 1 second), velocity and acceleration (move 1 pixel per frame) etc. The easy way out is to ignore it and live with one version being faster/slower than the other. Otherwise you need to make the necessary adjustments and possibly move to fractional arithmetic.

 

3. Color:

 

For this you simply need to make decisions; a. if it important to have a similar color & b. what color comes closest to what I have now? Just be aware that the PAL palette has fewer colors overall and the order of them is very different than the NTSC palette. There are, of course, colors which appear in one but not the other.

 

4. Music:

 

There is a slight pitch difference between PAL & NTSC, but the change is relative so each version will sound just as out of tune as the other.

 

5. SECAM

 

Same as PAL except for the colors & the B&W switch being hardwired to B&W. However, I don't know how big the SECAM market is. I haven't received any requests for a SECAM version of Skeleton+ yet.