HW NTSC->PAL

[frax]

Im modding a machine from NTSC to PAL (don't ask why ).

I realize I have to replace the GTIA but do I need to replace the ANTIC?

 

/frax

[ijor]

That depends on why, or for what purpose you want the conversion. Is it for software compatibility issue, or for getting a video NTSC signal, or both?

 

Replacing GTIA alone, disregarding the purpose, is not a very good idea. There are three, well actually four, differences between NTSC and PAL computers. And they are mostly unrelated one to the other.

 

For compatibility purposes, you usually need to replace ANTIC alone (not GTIA). The only gotcha is that you will actually break compatibility with software that checks the PAL flag in GTIA and adapts itself accordingly. I understand that there are not so many cases, but it is checked by the protection in several originals.

 

For the purpose of using an NTSC tv/monitor, you need to change the encoding/modulating circuitry. The refresh rate won’t change however, which might be a problem with some TVs. You need to replace ANTIC as well if you want 60 Hz refresh rate. And if you don’t change GTIA as well, the colors will be slightly off.

 

Lastly the main crystal is slightly different. I don’t know for sure if this is an issue at all.

[Gunstar]

yes, I replaced the Antic alone, and have so far, out of hundreds of programs and demos, only come across two that won't accept the Antic PAL alone. But you need to replace AT LEAST the Antic, the GTIA and PAL OS are what's optional (mandatory if you want 100% compatiblity, with Antic only, it's about 99%. And as stated, without the GTIA changed out, the colors are slightly off, I solve this just by adjusting the tint control on my 1084s monitor, not a big enough deal for me to bother swapping out the GTIA (especially since on my Xe, which has the PAL Antic, it's soldered in)

Edited February 21, 2006 by Gunstar

[ijor]

yes, I replaced the Antic alone, and have so far, out of hundreds of programs and demos, only come across two that won't accept the Antic PAL alone.

 

Hi Gunstar,

 

Just out of curiosity, you tested copy protected disk as well?

 

I know some protections check the PAL flag in GTIA and adjust accordingly the timing of the protection. One of these cases is, for example, MULE. I'm not sure what will happen in your case, it might break the protection, but it might also have the opposite result (that the protection check will pass when it should not).

[Gunstar]

yes, I replaced the Antic alone, and have so far, out of hundreds of programs and demos, only come across two that won't accept the Antic PAL alone.

 

Hi Gunstar,

 

Just out of curiosity, you tested copy protected disk as well?

 

I know some protections check the PAL flag in GTIA and adjust accordingly the timing of the protection. One of these cases is, for example, MULE. I'm not sure what will happen in your case, it might break the protection, but it might also have the opposite result (that the protection check will pass when it should not).

1022256[/snapback]

No, I haven't. The only copy-protected disks I have are NTSC. Most PAL programs are cracked images. So I could see now where that might be a problem, if you have original disks, but then, just download&use a cracked version.

[Rybags]

The OS is only different between PAL/NTSC on the 400/800 (unsure about 1200XL).

 

The XL/XE OS is the same in both cases. The only major things which are different anyway are the cassette I/O routines, since they use VCOUNT to determine the bitrate; the key repeat rate; and the cassette beep prompts.

 

Really, they should have used the same OS when they went to Revision B in the 400/800, but chances are it might not have fit within 8K.