[rusk]

> for a bunch of practical reasons

Basically makes it cheaper to build. You have a natural frequency there to use, and you don't have to come up with all this additional hardware to smooth out the existing frequency and come up with a new one.

I think there was a flip-side to this ... though NTSC had faster refresh, PAL had a higher resolution (more lines). I'm not sure, but I think this may have been a tradeoff.

[ldite]

It also reduced the effects of mains interference. If you had a 60Hz vertical scan, but there was interference from 50Hz mains (as there often was) then this would cause rapid rolling vertical distortion.

At 50Hz, even if the vertical sync wasn't actually locked to the mains frequency, any mains distortion would roll much, much more slowly, and be less offputting.

[mdpye]

You are correct. A black bar at the bottom of the screen is a nostalgic trigger for me! (When playing games which were designed for NTSC resolution on PAL screen. This was a generation later on the Amiga)

[boomlinde]

With analog TVs, it's the signal source that generates the synchronization signal. For the C64 specifically, like all the home computers and video game systems I know, this is derived from a crystal, not mains A/C. Since you need a pixel clock and horizontal clock at consistent multiples of the vertical draw time, using mains to derive the video sync seems very impractical.

My (basic) understanding is that having the beam move at roughly the same frequency as the A/C current is done to mitigate noise and distortion caused by other appliances, which earlier tubes were much more susceptible to.

[simias]

You have more lines with PAL but in practice since most of the game devs were either in Japan or in the US (with a few notable exceptions) most games were designed for NTSC and many didn't bother to increase the resolution when porting to PAL. Furthermore many games refreshed the display at half the video framerate so you end up with 25fps on PAL.

So in many cases you end up with games that run at 5/6th the nominal speed and have black bars at the top and bottom of the screen. PAL gaming was pretty crap, but of course at the time I didn't know any better and I didn't understand english anyway, so it's not like I had a choice...

[anticodon]

> Basically makes it cheaper to build. You have a natural frequency there to use, and you don't have to come up with all this additional hardware to smooth out the existing frequency and come up with a new one.

I'm not an expert, but I read that it was the idea but it was never implemented and TVs used independent generators.