Classic Computer Magazine Archive article

PAL/NTSC UPGRADE
by Nir Dary

   I can remember reading about PAL NTSC differences while I was living in Israel, but never had to deal with the problem until I came to the United States. Over here, many of my European games and demos didn't work properly on my NTSC systems. The music was out of synch, the screen was flickering or just garbage and some software just stuck and refused to work! I immediately called my father in Israel and asked him to ship me my 130XE PAL computer. Once it arrived, I hooked my PAL computer to my Magnavox NTSC color monitor and it worked!!!

   All of my PAL programs that had a problem on my NTSC computers worked fine. Except for one minor problem: the PAL system uses a different color modulation technique and all my video was now monochrome. I could only enjoy my Atari in black & white. To get my color back, I purchased a Multi-System TV; one that can display any of the three formats, NTSC, PAL or SECAM. This solved the problem. Color was back. All of my software ran properly.

   Six months later, my father sent me the rest of my Atari computers that I had left at home, four PAL machines. One, I gave to Bob Woolley so he could check his upgrades on a Pal computer. Another computer went to my friend Vince. This left me with two spare PAL machines that I could potz around with and not worry about crashing my- 1 meg PAL 130XE. It was time to find a better (and cheaper) solution to the PAL problem. How could we make NTSC computers work on PAL programs without spending a lot of time and money building a complete PAL system?

   [Nir, not being a technical wizard, proceeded to do what most of us 'experts' told him would be a major task - he altered an NTSC Atari to run PAL software on an NTSC monitor. Where expertise was lacking, he substituted determination and experimentation.... ed.]

   The solution is as simple as replacing the NTSC ANTIC with a PAL version and changing one byte in the OS ROM. All that great European software will work on an NTSC Atari computer (600XL, 800XL, 65XE, 130XE) in COLOR on a regular color NTSC monitor!!!

   Itay Chamiel from Israel asked me if the upgrade will work on a computer with a modified OS like Ultraspeed OS+, Omniview, Omnimon etc... The answer is yes! While Plugging a Pal ANTIC chip will fix a majority of the problems, I have found at least two programs that also needed the OS to be changed. It is possible to modify Omnimon, Omniview or any OS that is on a standard 27128 EPROM chip, but the Ultraspeed OS+ seems to have some sort of copy protection. You should check with the OS supplier before you copy his chips for this type of thing. If enough users inquire, they may even produce upgrades.

   The modification will be available soon. It will include a PAL ANTIC chip, a modified OS, two demo disks and a small manual (it doesn't need much to explain how to plug chips!!!) The cost will be around $30 plus shipping, and the number of upgrades will be very limited since the supply of PAL ANTIC chips is minimal.

Nir-PAL Explained

So, read the above text from Nir Dary. Sound interesting? You should hear Ben Poehland rave about T-34 (see review section). Ben is not a gamer by any means, but for THIS, he is excited. That should tell you something about how important Nir's upgrade is to the North American Atari community. Nir is from Israel, a PAL country. When he arrived in the US and had to use an NTSC computer, he realized that us local folks were really missing something. Being a true Atari citizen, and even though he acquired a PAL system for use over here, he was determined to solve the PAL problem for the rest of us. And, he did. You must have Nir's upgrade to run software like T-34 and many other great European products. Those users across the Pond are still cranking out top quality 8-bit stuff and YOU are going to miss it all unless you hack at least one of your 8-bits with this nir-PAL upgrade! (clever play on words.... not a true PAL system, but a hybrid that's just perfect for us NTSC 8-bitters)

Now, for the techie talk. The PAL software that we get from overseas is developed on a system that differs from our NTSC (US) computer in two ways: the vertical blanking interval and the color modulation technique. The VBI differences cause out of time sound and DLI interrupts, while the color differences cause a loss of color on our NTSC monitors and TVs. By a great stoke of luck, these two processes are handled by different sections of our machines and Nir managed to solve the VBI and DLI problem without affecting the color. You see, the VBI is done in ANTIC and the color is generated in GTIA. So, (it seems so obvious now) all Nir had to do was plug in a PAL ANTIC chip and leave our GTIA the way is was. Voila! PAL VBIs and NTSC color! Brilliant! The other tweak is to the OS. The OS sets the PAL flag at $62 by reading the hardware in GTIA at $D014. Since we still have an NTSC GTIA chip, we need to change $C386 to $01 (also change $C000 checksum value from $11 to $12) so the OS thinks we are really PAL. The result is a video output with a 50hz vertical frequency and 315 scan lines. You may notice a slight flicker under fluorescent lights from the 50hz, but it is not objectionable. One of my monitors required a little vertical hold adjustment and you may want to adjust height and vertical linearity for taller picture. Otherwise, it is a drop-in if you have socketed chips. If you have soldered in chips on a 130XE, be very careful about de-soldering them. You WILL trash your machine (ask Nir).