Is there a name for a 60th of a second (an NTSC/PAL60 cycle)?

[potatohead]

That's a good one.

[R.Cade]

Thanks guys - I never thought of it in this way. Thanks for taking the time to explain it.

[Bryan]

You're welcome. I've always found analog video to be fascinating stuff. I'm kinda sad to see so much clever engineering going away.

[potatohead]

Me too.

 

I've had a lot of fun programming video displays over the last 10 years. (Micro controller based things) The analog world has a lot of advantages over the digital one when it comes to little systems and making signals. It just takes less, and the results can be excellent.

 

As I look into digital things, like HDMI, there is some equally good engineering. It just seems harder to grok and a lot harder to program and tinker with... sigh.

[Bryan]

Yep, plus low-resolutions weren't so offensive looking. Things could be soft instead of purely blocky.

[potatohead]

Totally. I'm kind of amazed really. For this reason, I keep a couple old CRT devices. Some of the pixel art was really clever, and all the ways people have exploited the old standards is just fun to learn about.

[bogax]

Here's a better picture of how the interlacing is meant to work in NTSC

(from this page)

 

If the scan returns to the top at the same place horizontaly (instead of being displaced by half as in that picture) you would presumably

scan the even and odd fields in exactly the same place horizontaly

In the olden days that wasn't possible be cause the half line displacement was built into the TV it's self and it could take seconds

or minutes (or never) for the television to sync with the signal

Edited January 1, 2016 by bogax

[R.Cade]

It's pretty amazing that this was invented over 100 years ago. It is still an amazing achievement, and must have seemed like witchcraft back then.

[bogax]

It's pretty amazing that this was invented over 100 years ago. It is still an amazing achievement, and must have seemed like witchcraft back then.

 

Without electronics

[Bryan]

 

Without electronics

I remember watching a documentary about it on YT. Pretty hardcore stuff!

 

(anyway, we're way off topic)

[+xucaen]

Your 3rd option from the bottom gives you the answer - 60 FPS divided by 60 is an F.

[maiki]

How can you call it a frame when a frame does not have to do anything with a 1/60 of a second... you can have a game running at 15 fps...

[RevEng]

If at least some of your 2600 game doesn't run at 60Hz, you can't race the beam and draw the screen. As mentioned above, each 240p frame is displayed at 60hz.

[alex_79]

How can you call it a frame when a frame does not have to do anything with a 1/60 of a second... you can have a game running at 15 fps...

When a game is said to run at 15 fps, it means that it can it can do calculations to render 15 new frame of graphics per seconds, but the video signal must still be at 60Hz (or 30Hz interlaced or any other standard signal accepted by the TV or PC monitor in use). Some frame in the video output will be duplicated to reach the required framerate. This is achieved either by hardware (the video chip will just output the same image until it's updated by the cpu) or by software (as in the case of the 2600, when the programmer must ensure that the video timing is correct). I think that the only 2600 game that can have occasional framerate drop is Boulder Dash, which takes more time to calculate a new frame when there are many objects on screen. But it stills outputs a steady 60Hz signal, or the TV would lose sync...