Re: [stella] PAL Conversion Preferences

Subject: Re: [stella] PAL Conversion Preferences
From: "Eckhard Stolberg" <Eckhard_Stolberg@xxxxxx>
Date: Sat, 16 Nov 2002 15:17:55 +0100
Hello Fabrizio,

> I have both a 50hz and a 60hz PAL version of Space Treat basically ready
> here, and have been thinking and thinking about which version would be
> preferable to release..

Since I suppose the carts will be made when they are ordered,
you could release both versions, and let the customers decide,
if they want the PAL50 or the PAL60 game.

> Besides the speed and TV compatibility issues that have been mentioned, I
> was a bit worried about 7800 support: will a PAL 7800 correctly display a
> 60hz 2600 game?

In 2600 mode a PAL 7800 will work mostly like a PAL 2600.
The frame rate control is all in the game. If your game
works with a PAL 2600, it should normally also work on a
PAL 7800.

The only real difference between the two is in the handling
of the undefined bits in the TIA read registers. On a 2600
the undefined bits will get the state of whatever value was
on the data bus last, while on the 7800 these bits will
always be 0. So if you are accidentally doing "LDA $07"
instead of "LDA #$07", and then rely on the state of the
six lower bits, it might work on the 2600, but not on the

And of course all (I think) PAL 7800 have the TIA chip
that has problems with Kool-Aid Man. so if your game does
some similarily wierd positioning sequence, it will not
work on the PAL 7800. But it wouldn't work on some 2600
Jrs. either.

> Probably that will be a non issue, but since I have zero knowledge of the
> 7800's internals, and since the NTSC Space Treat doesn't work on PAL
> I had to put some thinking into that :)

Is that a hardware issue with the cartridge, or does the ROM
fail on Cuttle Carts, Superchargers or 7800 RAM carts too.
If it's the later, you should check your code for instructions
where you meant to use immediate addressing, but forgot the #.

> Anyone have some experience with testing on the 7800? (I believe you have
> :))

The Cuttle Cart and the Supercharger don't work on the PAL
7800 without a small modification (and might not even work
with the modification either). Therefore I use a 7800 RAM
cart, that can play most 2600 4K games as well to for 7800
compatibility testing.

Ciao, Eckhard Stolberg

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