I have an NTSC machine. I want to be able to switch it into PAL mode to run PAL demos and games.

Yes, the topic has been brought up a number of times, however there's a bit of information that I'd like to acquire. How does the PAL VIC-II differ from NTSC VIC-II?

What happens if I swap the crystal in my C64 and set the PAL jumper, leaving the NTSC VIC-II in place? Would I have sync issues with PAL games/demos?

Does the 50Hz/60Hz refresh depend on the clock input, or is that something on the silicon inside the VIC II?

PAL or NTSC is hardwired into the VIC-2 chip, so you at least need one of each to do a switchable system.

The master clock and divisor are also different, the VIC-2 divides the clock down to be supplied to the CPU.

Unsure if you can do a switchable system with only one clock crystal - at the least you'd have colour encoding issues for the "foreign" video signal.

PAL/NTSC is much more than simply 50/60 Hz, there's also the 312 vs 262 scanlines per frame and the colour base clock difference between them as well - and to make things even more complicated the number of CPU cycles available per scanline is different, although that's controlled by VIC-2 revision.

Just import a PAL Commie, plus cheap signal converter if you have to. I hear new TVs over there are mixed mode nowadays, so you should be ready to roll.

I mean, how cheap and convenient can it be in this day and age?

I have a switch to switch between the crystals. Then I swap the Vic-II chip. I just wish there was a board you could put that would swap the Vic-II chips automatically. But, It works well.

Really, if you play 'non-original' games. Most are PAL I found out. I almost now keep mine always PAL because of this. Nice playing Giana Sisters without flashing blocks.
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And if you're really into building for your twin system computer, you could attempt a 'split level' C64 case somehow.

You know, have each motherboard, one atop the other, with a switcher you've made to share video and keyboard connections. An SD interface in each serial socket and you're away.

Is it possible? Take the top off one Commodore to somehow seat the other case on top? Might need some work to shoehorn stuff together but I suspect it's do-able. (Either that or there's some dead PC's case somewhere to recycle, or an Amiga's.)

Can I MUX together two VICs? The one I need would be enabled and the other disabled. I'm thinking of making an adapter board for two chips, as well as a selector board to select crystals.

Perhaps even put a quality VGA or DVI converter on that same board, to get some nice sharp pixels. Basically an enhancement of the same idea as those guys doing vertical line fixes on this same forum.

Too bad my machine is a shielded '83, I've got no room for such a board, at least without removing the shield.

You can do that? That works as a concept?


Though to ask another question, how come PAL units seem to take NTSC games in their stride? I've downloaded countless US games and they all work. Even straight transfers to disk or tape image.

You can't really have 2 VICs active - it supplies the CPU clock as well as performing memory Refresh.

So did anyone actually get around to designing a board to house both PAL/NTSC Vic II's? I'm thinking maybe something that has a "default VIC II" jumper on board as well as the ability to switch mode at boot time by holding down either "P" (PAL) or "N" (NTSC).

I would love for someone to do this. I have a switch for the crystals and a zif socket in the VIC-II socket.
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BD you should build this board.
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Would it be possible for someone on here to design such a board in eagle format so we could send it off to a board producer?

not sure about the demand, most people just have a stand alone PAL system...
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