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US friends who put a PAL ANTIC in their NTSC A8....What are your results ?


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As most of you know by now I'm working on a switchable solution for ANTIC.

 

During testing I ran into the following:

 

I have a NTSC 800XL and put in a PAL ANTIC. When I use this machine on my B&O MX4000 TV or f.i. A Sony PVM CRT monitor, i get perfect color picture.

 

However, as soon as I try some more modern LCD TVs is shows a vertically striped black and white picture. Tested this on various TVs. I have a feeling that the LCD TV is probably too intelligent and is confused by the "hybrid" signal.

 

Now, I live in PAL territory but I assume that today LCD TVs are the same everywhere because they seem to accept all standards globally now ? Or would US LCDs have a bit different firmware (settings) ?

 

Have any of you US guys put a PAL ANTIC in their NTSC machine and had good results with LCDs ?

post-25272-0-34368900-1525514619_thumb.jpg

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Most monitors can deal with RGB at 60Hz PAL or 50Hz NTSC. All you'll notice is the different refresh rate and possibly aspect ratio. I should expect Y/C video to be a rather hit-and-miss affair with mixed GTIA and ANTIC, however. Very much try it and see. It took me two attempts to purchase a USB s-video capture device which would even entertain PAL output from an A8, let alone handle hybrid video.

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I installed one in my 800XL when I did my U1MB upgrade to it. I use a 90's NTSC Panasonic TV. It seems to work on this TV but the bottom is chopped off. On another TV the screen flips and I cannot see the screen. Seems to play PAL games fine. Haven't tested on any modern LCD screens.

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Why would one do this?

Swapping ANTICs has two reasons:

 

1) US users with NTSC machines can run software which was created for PAL. Mostly demos and games.

 

2) European users with PAL machines can run the games on the original NTSC speed. Games play slower on PAL machines and IMHO most of the games designed with NTSC in mind run smoother at NTSC speed.

The other way around can alombe true, f.i. Dropzone and Elektroglide were designed in PAL territory and for PAL systems. The games are TOO fast when run on NTSC machines.

 

I have designed a PCB that let's you install two ANTICs in any A8 and switch between them. This would solve the need to have two machines.

 

As mentioned here, it is not a FULL conversion. For that you also need to swap GTIA, but the hardest part is installing the extra crystal and the required support components for the crystal that are lacking on NTSC machines...

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I have tried 4 different LCD TVs now and on picture syncs correctly but displays a picture as shown above, black & white and vertical stripes. 1 TB does the same but even has a hard time syncing the picture, making it unusable....mind you this is a very old and extremely cheap LCD TV.

 

I wonder if there would be an easy solution for this.

 

I dont understand why my B&O MX4000 CRT TV has absolutely no issues displaying the hybrid PAL signal in full color, while LCDs choke on it. I bet the LCDs "analyze" the incoming signal by certain elements of the signal (sync ?) and make it assume some wrong "settings" following that ?

 

Jon, RGB always uses separate sync signals which probably makes it easier to force a monitor or TV to sync correctly. With composite video of course everything is mixed together.

 

I wonder if we could trick an NTSC A8 to put out a hybrid NTSC GTIA/PAL ANTIC hybrid PAL signal somehow....maybe change clock frequency ?

I assume most LCD TVs in the US will happily display a real 50Hz PAL signal is like European TVs will display NTSC 60Hz happily ?

 

It might be that Sophia would be the ideal companion of my ANTIC switcher. Using RGB it should be no issue at all....not sure about any of the digital output formats.

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Jon, RGB always uses separate sync signals which probably makes it easier to force a monitor or TV to sync correctly. With composite video of course everything is mixed together.

It's not a question of sync: it's a question of colour, and colour is implicit to RGB. Therefore if the monitor displays an RGB picture at all, it displays it in colour. If a PAL monitor worked only with 50Hz video, neither Y/C nor RGB would work at 60Hz.

 

As already mentioned (and for the reason outlined above), VBXE (like Sophia) gets around all these issues, seemingly on a consistent basis. I'm not sure there's an easy solution to the lack of Y/C colour on a hybrid setup, however.

Edited by flashjazzcat
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So you use RGB out ?

Correct. I feed it into my XRBG-mini and it works great.

 

For many years I was looking for a 'NTSC/PAL' solution but could never get PAL to display in color. The Sophia finally did the job :)

 

 

I have designed a PCB that let's you install two ANTICs in any A8 and switch between them. This would solve the need to have two machines.

Is that PCB available? That sounds like something that would be very handy if it fit into my 1200XL...

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Is there an artifacting core available for Sophia which emulates PAL colour blending? Such a thing exists for VBXE (and can be activated and deactivated in software), and without it, one depends on the legacy video output for things like APAC and other software graphics modes.

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The project would absolutely need to have full PAL and NTSC conversion, GTIA/ANTIC, crystals and all to change completely to either PAL or NTSC to work in pretty much anything you want TV/monitor wise. Hybrid will only ever work right on certain monitors that can handle it. I used a Hybrid ANTIC only for years without problem, on my Commodore 1084S 50/60Hz CRT. But that monitor died (I do plan to fix it one day) and after several attempts at different supposedly 50/60HZ TV/monitors and video adapters/converters, which do handle PAL or NTSC separately, but not a hybrid signal, I finally decided to make the leap to full PAL one of my 1200XL's and have another (currently in repair) that will remain NTSC. I have a third, which I will make a Hybrid and use it with my 1084S once I have both working again.

Edited by Gunstar
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PAL needs 4.43something colorburst for showing colors.

When you are lucky, the tv sees 60hz and clocks on the 3.54 Mhz ntsc burst, giving colors.

But most pal tv's clock on the 4.43 and when it is missing you get b/w.

 

I understand why; pal antic waste less time in nmi-cycles....

more scanlines....

;-)

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I think Sijmen already gave the answer to this question ;) The PAL computer with the NTSC antic (according to Sijmen changes the framerate and the scanlines only) is identified as PAL 60 on the LCD we (Level42 and I) used.

 

But, now I have a question ;-) The Sharp Aquos TV, we used in a second test, is able to display a NTSC signal with the colorburst at 4.43 Mhz (in stead of 3.58 Mhz) and that one did not display color either..... How is that possible?

 

6lxa7HC.jpg

Edited by Fred_M
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I read up on NTSC and PAL a bit. The color burst itself doesn't contain the color information. It's only something like a "trigger".

 

Here's a good picture of how an NTSC signal looks like that displays a color bar test screen:

 

7215.75_2500_NTSC_5F00_Color_5F00_Bar.JP

 

This is an actual oscilloscope picture:

4657.P01_5F002800_NTSC-Composite-Video-S

 

 

it shows this picture:

3125.P03_5F002800_ColorBar_2900_.jpg

 

So you can see the color burst is the "small" signal right after the (negative) sync pulse. The actual luminance (brightness) and chrominance (color) information comes after it. You can see the separation of luminance and chrominance at the white (first bar) and black (last bar). There is NO color information there, it's just an amplitude (brightness) level (high level = bright, low level = black). (This was done to keep B/W TVs able to produce a picture from a color signal)

 

The color information itself is "encoded" differently on both systems. PAL solved the poor color issues of NTSC. Anyway...those signals are not compatibel. So....if an intelligent TV like "modern"LCD TVs "thinks" it's receiving a signal in NTSC format (because it detects certain specs of that signal) the chip-set doing the whole analogue to digital conversion will try to decode the color using that format.....and fail....displaying a B/W only picture. Makes sense.

 

 

And that brings me back to the question I have: why does it work one way around ....but not the other ?

Edited by Level42
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Pal machines generate a 4.43 burst, so you have colors on PAL sets.

 

Sijmen.....this is an interesting thing: are there still "PAL sets" ? Are LCD TV's still being made specifically for NTSC/PAL territory ? Or maybe they simply have a different firmware, but that still separates them. You could be right about that.

 

But that would mean that our US friends should have NO trouble putting a PAL ANTIC in an NTSC A8....but "should" have trouble if they have a PAL A8 there and put a NTSC ANTIC in it.

 

However, Fred and I assumed that TV's today are universally the same since they all seem to accept both standards......

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I read up on NTSC and PAL a bit. The color burst itself doesn't contain the color information. It's only something like a "trigger". ?

 

PAL needs 4.43 mhz burts, NTSC needs 3.54.

If the monitor/tv does not detect the burst, you have no colors.

 

GTIA produces the color, not ANTIC.

 

PAL mainboards have an additional 4.43mhz circuit to generte the required burst.

 

All depends on the monitor/tv if it correctly detects this burst-signal.

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So what you are saying is that in a NTSC 8-bit Atari with an PAL Antic (without the crystal and GTIA) the signal will be a PAL signal (framerate en scanlines) with the colorburst at 3.54 (NTSC GTIA). So a PAL 3.54 signal is generated. That mode is not supported on the most (if not all) LCD screens and we get black and white colors.

 

Makes sence ;) Thanks :thumbsup:

 

@Level42, I think the "other way around" works, because the PAL 60 mode is/was used by various consoles in the last decades. So that combination is much more common. From wikipedia: "A "PAL 60" signal is similar to an NTSC (525/30) signal, but with the usual PAL chrominance subcarrier at 4.43 MHz (instead of 3.58 as with NTSC and South American PAL variants) and with the PAL-specific phase alternation of the red colour difference signal between the lines."

 

Looking at the specs of your Beovision MX4000 CRT, your CRT supports PAL-M. PAL-M at Wikipedia: "In Brazil, PAL is used in conjunction with the 525 line, 59.94 field/s system M, using (very nearly) the NTSC colour subcarrier frequency. Exact colour subcarrier frequency of PAL-M is 3.575611 MHz. Almost all other countries using system M use NTSC."

 

According to beoworld.org your CRT supports: "CTV system: according to type: B/G/D/K/L/L´/I/M PAL, SECAM, NTSC on AV " PAL-M is in there ;)

 

Sadly PAL-M was only used in Brazil. I think most LCD TV's do not support that type of PAL. My Sharp Aquos does not support PAL-M.

Edited by Fred_M
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