Cartridge Game Picture Position out of place

[Kalle]

I have some VIC20 game cartridges that does not work properly. The image is kind of off-screen.

This is an example:

I have two cartridges with the same problem: Sea Wolf (VIC-1937) and Alpha Alarm (VC-1901).

I have tried two different VIC-20 computers, both of them has the same problem. Both of them also have no other problems.

Does anyone have any clue whats wrong?

Both of my VIC-20 is PAL version. Maybe its a PAL/NTSC thing?

Thanks in advance.

[srowe]

Both of my VIC-20 is PAL version. Maybe its a PAL/NTSC thing?

Yes it is. Most cartridges allow you to centre the screen using the cursor keys.

[Mayhem]

The screen registers for PAL and NTSC were different iirc. Many games, especially Commodore ones, allowed you to reposition the screen using the cursor keys. Some don’t sadly.

[Mike]

The screen registers for PAL and NTSC were different iirc.

To be more precise: the PAL and NTSC versions of VIC-I have the relevant registers (XPOS, YPOS) at the same place, but they need different default values to correctly center the display window.

The KERNAL provides the correct default values in an init table at $EDE4. That is one of the reasons the VIC-20 KERNAL is different for PAL and NTSC! Other XPOS and YPOS values should be derived from that table, via offsets. That easily recenters the screen in case the display window is resized, but either noone told the cartridge writers about that table, or they didn't care.

That being said, it is quite easy for new programs to be written TV system neutral regarding that specific issue. Read here for more details.

[...] Alpha Alarm (VC-1901) [...]

That is the German "translation" of VIC Avenger, applied as sticky metallic label. How does the cartridge display the name in-game? Still as "VIC Avenger" (I still hope a ROM with the original name, VIC Invaders, pops up someday ...)?

[Kalle]

Yes it is. Most cartridges allow you to centre the screen using the cursor keys.

Yes! The arrow keys worked! Great!

Edit: Sorry for the bad image, tried to upload using my phone..

[Kalle]

That being said, it is quite easy for new programs to be written TV system neutral regarding that specific issue. Read here for more details.

Thank you for your answer, very interesting.

That beinThat is the German "translation" of VIC Avenger, applied as sticky metallic label. How does the cartridge display the name in-game? Still as "VIC Avenger" (I still hope a ROM with the original name, VIC Invaders, pops up someday ...)?

This is indeed a copy of VIC Avenger under the metallic sticker (i peeled it off and put it back on again.

There is no name displayed in-game as far as I can see. The title screen only has instructions.

Thanks for all the answers! I really learned something today.