Zaxxon

[Wrathchild]

I took at look at Zaxxon a couple of years back to see if there was a way to remove the (for me) annoying bar at the top of the screen but didn't, on a quick scan, see a simple way of doing this.

 

Question is, is this just a side effect of how the game was written or is it there for a purpose?

[spookt]

If you mean the vertical one in the top left it's your altitude IIRC. There's on in Super Zaxxon too.

Edited March 12, 2010 by spookt

[PeteD]

Nah, the altitude is obvious, it's the big bar down the side. I think he means the little white thing that follows your ship? Not sure if it's to help you tell where your ship is (if that's the one you mean) and it isn't in the Arcade or any other version afaik.

 

*edit*

It seems to be a bug. PMBASE is at $38, if you check $3d00 there's some "stuff", try writing a few FF's in there with a debugger and watch the thing crap out and crash. I think they decided to use (or accidentally used) a bit of PM ram for some pointers and stuff.

 

 

Pete

Edited March 12, 2010 by PeteD

[Kr0tki]

That bar is on the very first scanline, so it is not visible on NTSC TV's of the time. The author either didn't know about it or didn't bother since nobody would see it anyway.

Edited March 12, 2010 by Kr0tki

[Wrathchild]

Yep, PeteD's right. So if we can find some alternative home for that data then it could be cleaned up with any luck Didn't know that about the NTSC 1st scanlne, thanks for that Kr0tki.

Edited March 12, 2010 by Wrathchild

[spookt]

Hmm never noticed that before. Is it really worth it? It's not exactly the greatest game ever.

[Kr0tki]

Yep. In NTSC the visible screen area is 480 lines - which is precisely the number of lines generated by the Atari. Then there's overscan - around 3-5% of screen at either of four sides is made not-viewable, and that includes a few top and bottom lines of the Atari screen.

 

In PAL, the screen height is 576 lines, and even after taking overscan into account, the area left visible is on most TV sets more than 480 lines, so we Europeans can see all of the Atari-generated scanlines.

Edited March 12, 2010 by Kr0tki

[Tempest]

Got a picture? I'm kind of curious now.

 

Tempest

[Kr0tki]

http://www.mobygames.com/game/atari-8-bit/zaxxon/screenshots/gameShotId,149615/

Or did you mean a picture from a TV?

Edited March 13, 2010 by Kr0tki

[walter_J64bit]

Here's the Arcade on You Tube

[Tempest]

Can someone point out the bar? I'm not seeing it.

 

Tempest

[Kr0tki]

It's the short white horizontal line on the very top of the screen, directly over the player's ship.

Edited March 13, 2010 by Kr0tki

[Kjmann]

Here's what it looks like Matt.

 

It is pretty irritating.

 

 

 

The two Problems are circled in Yellow.

Edited March 13, 2010 by kjmann

[+Cafeman]

This looks like player or missile clutter, but which player or missile? In the 5200 bin file, the Player Missile base is $3800. I messed around resetting the tops of each player and missile data areas , and I saw twice where i had affected that bar. But it also messed up the charset graphics for me (could be just an emulator issue though). So I guess that's all I can offer.

[Rybags]

I can't remember there being garbage at the bottom when I used to play it years ago, but maybe it was there.

 

If it is the case they've invariably used it as workspace, then maybe the best solution would be DLIs to enable/disable DMA to get rid of it.

[+Philsan]

I can't remember there being garbage at the bottom when I used to play it years ago, but maybe it was there.

With Altirra I don't see any garbage at the botton, top line only (without garbage).