40 replies to this topic

[flashjazzcat]

This may be totally dead in the water, but here goes...

Would anyone be interested in a GTIA adapter board for the 1200XL which drives the PAL pin with the proper osciallator signal for PAL operation? This is the kind of thing that can be made up relatively easily on veroboard if you're adept with a soldering iron, but it's usually awkward to fit and wire up. The adapter would have the oscillator circuit on-board (including crystal), and would sit in the GTIA socket. You'd need a PAL Antic and GTIA. There'd be no soldering required.

Would anyone be interested in such a thing?

[svenski]

I might be interested as you said the magic words "no soldering required"

[Guitarman]

I'm a MOD hog, I'm sure I'd be interested!!

[Gunstar]

I'd be interested in one, but being currently unemployed*, it depends only on if I have the money when they are available. I'm currently repairing and upgrading 3 1200XL's, one will be for sale eventually, one for myself and the last as back-up, parts
.
But I'd love to get 2 of them, one for myself, but as an experienced vintage computing eBay seller, I know it's worth every penny to upgrade these old computers as much as possible. It's the only way they become worth enough to make the entire endeavor worth-while.

I can make my own upgrades, but if priced right, I'll take a plug and play device anyday over the drudgery of de-soldering and soldering.

You specified "1200XL," but if it's just a matter of plugging it into the GTIA socket, shouldn't it work on ANY 8-bit? I have an 800XL and 600XL that are next in line for repair and upgrading...

*self-employed lawn/landscaper in drought-ridden Texas.

Edited by Gunstar, Thu Oct 6, 2011 3:23 PM.

[thgill]

Sounds like taking the NTSC 1200XL and doing a true conversion to PAL instead of just replacing the Antic (which is like quasi PAL)?

I would be up for one as well.

[Gunstar]

The question I have about this upgrade is; does it create incompatibilities with NTSC software to go full PAL. I like the quasi PAL upgrade because it runs the vast majority of PAL software already, mostly just demos that won't work. Plus, it remains, as far as I know, completely compatible with NTSC software.

So I guess the short of it is: do PAL Atari's have compatibility problems with NTSC software?

[flashjazzcat]

Gunstar, on Thu Oct 6, 2011 3:01 PM, said:

I can make my own upgrades, but if priced right, I'll take a plug and play device anyday over the drudgery of de-soldering and soldering.

Price depends on cost of PCB run and sourcing crystals, but it won't be expensive. If I have to charge more than 15GBP for something like this, something's gone wrong.

Quote

You specified "1200XL," but if it's just a matter of plugging it into the GTIA socket, shouldn't it work on ANY 8-bit? I have an 800XL and 600XL that are next in line for repair and upgrading...

I suspect it would fit a 600XL or 800XL, although those machines already have the circuitry in place for the PAL sync (they just need the components adding). However, for those who don't like soldering...

thgill, on Thu Oct 6, 2011 4:16 PM, said:

Sounds like taking the NTSC 1200XL and doing a true conversion to PAL instead of just replacing the Antic (which is like quasi PAL)?

Yes - exactly. My experience of the 1200XL has demonstrated that "quasi-PAL" throws up all kinds of weird results (expecially with benchmarking software), and replacing GTIA and Antic together produces mono video output, since the colour sync is off. This mod will give you a genuine PAL 1200XL.

Gunstar, on Thu Oct 6, 2011 6:54 PM, said:

The question I have about this upgrade is; does it create incompatibilities with NTSC software to go full PAL. I like the quasi PAL upgrade because it runs the vast majority of PAL software already, mostly just demos that won't work. Plus, it remains, as far as I know, completely compatible with NTSC software.

So I guess the short of it is: do PAL Atari's have compatibility problems with NTSC software?

Most of the TV-standard specific software I've encountered has required PAL. I don't know much about NTSC-only stuff. Anyone?

Edited by flashjazzcat, Fri Oct 7, 2011 3:41 AM.

[jvas]

I'm interested in it too ...

[flashjazzcat]

Right - we need a PCB manufacturer in the UK then...

[Gunstar]

"I suspect it would fit a 600XL or 800XL, although those machines already have the circuitry in place for the PAL sync (they just need the components adding). However, for those who don't like soldering..."

Oh, right, I temporarily forgot that 1200XL's where only released in North America...I was was forgetting that it was more than just OS differences due to that.

[mimo]

Depending on price, yes I am interested

[flashjazzcat]

Since the usual info sources were dry, can someone technical please explain to me the exact signal flow regarding the PAL and OSC pins of GTIA (pins 16 and 28 respectively)? I'm trying to figure out whether we can make a low-profile adapter board, but that's no-go if we have to do more than simply remove jumper W10 on the 1200XL. OSC is tied to the main oscillator output on my 1200XL. And what's the exact purpose of pin 16 (PAL)?

[Rybags]

PAL input gets the ~ 4.48 MHz PAL colourburst input.

OSC pin... no idea if PAL machines use that. GTIA has phi0 and 2, and the master clock on a PAL machine isn't of much use as a colour delay reference. Actually, I don't think the colour generation circuit relies on any "clock speed" for generating the actual phase delay.

[flashjazzcat]

Thanks Gary. Well - PAL (pin 16) appears to be floating once W10 is removed. So surely if we fit a low-profile adapter and remove W10 on the board, we can feed the new signal to the isolated PAL pin?

[Rybags]

No idea. Since we have no PAL 1200XL to compare, I suppose the best course is to see what the differences are in others like 800XL.

It seems a little weird to me that seperate pins were used for essentially the same thing in the first place. Unless OSC is involved in giving the 1/4th clock required for hires pixels.

But my impression was that those delays were "electrical" and made possible by design.

[flashjazzcat]

Beetle could give us the answer, since he's done the PAL mod. However, he never got back to me when I emailed him some months back.

[mimo]

flashjazzcat, on Tue Dec 27, 2011 3:42 AM, said:

Beetle could give us the answer, since he's done the PAL mod. However, he never got back to me when I emailed him some months back.

Beetle did not do that mod iirc, someone did it for him. Maybe Wolfram?

[flashjazzcat]

mimo, on Tue Dec 27, 2011 12:32 PM, said:

Beetle did not do that mod iirc, someone did it for him. Maybe Wolfram?

Aha - thanks. I'll drop Wolfram an email.

[Mathy]

Hello Jon

I'm interested too.

You don't need a manufacturer in the UK. You need a good one, doesn't matter where the company is located. Often companies from Bulgaria or China are used. Candle, Hias, Wolfram etc. can tell you which ones are reliable.

Why don't you use the schematics to the XL or XE computers to see what OSC and PAL (pins) are used for in these computers? Since the GTIA and ANTIC in the 1200XL are the same as those used in the XL's (apart from maybe the refresh counter) and XE's, you can just copy what Atari did for the PAL XL's and XE's.

Mathy

[Dropcheck]

Mathy, on Tue Dec 27, 2011 4:24 PM, said:

Why don't you use the schematics to the XL or XE computers to see what OSC and PAL (pins) are used for in these computers? Since the GTIA and ANTIC in the 1200XL are the same as those used in the XL's (apart from maybe the refresh counter) and XE's, you can just copy what Atari did for the PAL XL's and XE's.

Mathy

That's an idea. Does someone have the schematics for XL/XE PALs?

[UKRetrogamer]

Count me in.

[Gunstar]

flashjazzcat, on Fri Oct 7, 2011 3:40 AM, said:

Gunstar, on Thu Oct 6, 2011 6:54 PM, said:

The question I have about this upgrade is; does it create incompatibilities with NTSC software to go full PAL. I like the quasi PAL upgrade because it runs the vast majority of PAL software already, mostly just demos that won't work. Plus, it remains, as far as I know, completely compatible with NTSC software.

So I guess the short of it is: do PAL Atari's have compatibility problems with NTSC software?

Most of the TV-standard specific software I've encountered has required PAL. I don't know much about NTSC-only stuff. Anyone?

I'm not sure what you mean by the above statement, since all the software I've owned for years is NTSC with an NTSC Atari. So obviously most software doesn't require PAL where I come from...What I'm saying is that with my NTSC 1200XL, it runs all the NTSC software I bought living in America, and when I expanded my Atari software horizons in the last decade, most PAL software wouldn't work on my NTSC 1200XL. But once I put the PAL ANTIC into my 1200XL, it works with the majority of PAL software, but I also retain compatibility with my NTSC software. I'm asking if I make my 1200XL FULLY PAL, do PAL machines normally have problems running North American software? I don't want to trade NTSC compatibility for PAL, either I get Full compatibility with both NTSC and PAL, with a PAL board, or I stick with my quasi-PAL NTSC 1200XL which works fine for me, with about 80% of the PAL stuff I try; it's mostly just PAL demos that don't work for me now.
Would it be possible to have a PAL board that would allow one to install a switch to choose between PAL or NTSC modes?

Do PAL owners have any problems running NTSC software on their Atari's?

Edited by Gunstar, Tue Dec 27, 2011 8:50 PM.

[oracle_jedi]

Count me in for at least one, probably two.

@Gunstar - a true PAL machine should run pretty much all NTSC software. Switching from the NTSC/50 you have now to a true PAL signal will change the following:

Output signal will be true PAL, and require a PAL compatible monitor. Many North American colour monitors could handle a 50Hz signal as long as it was still NTSC colour encoding. The updated machine will now be transmitting PAL colour signals. Your 110V Commodore 1701/1702/1084 will only show black and white.

Artefacted colours wont work anymore.

Software that inspects the PAL/NTSC personality of the GTIA will now see PAL, not NTSC.

I have a PAL 800XL, an NTSC 1200XL and a quasi-PAL 1200XL. I cant think of any software that runs on the quasi-PAL 1200XL that wont run on the 800XL.

[flashjazzcat]

These are the schematics I have for the 800XL:

 800xl.zip   190.05K   14 downloads

[ijor]

Mathy, on Tue Dec 27, 2011 4:24 PM, said:

Why don't you use the schematics to the XL or XE computers to see what OSC and PAL (pins) are used for in these computers?

OSC is always used. It is the main system clock source in all boards and GTIA/CTIA variations. PHI0 and PHI2 are derived indirectly from this input.

PAL is used only on PAL GTIA chips. The pin is not connected on GTIA NTSC chips.

XL schematics show a jumper to connect this pin to OSC. This would affect PAL GTIA chips only.