Computer Ambush "illegal disk!" Boot error. Need help.

[IMBerzerk]

Hi.  I'm posting this here as a hopeful shot in the dark to help me sort an issue with one of my all-time favorite games.  Only thing is...my intent is to get it on an emulator in Retropie. Lr-atari800 to be exact.  Here is where I'm at.

 

In a W10 environment, I tested the same rom on Atari800Win PLus 4.1 and Altirra/x64 2.40.

 

Atari800Win - result. "cannot boot --> illegal disk!" message displayed just as lr-atari800 does. Selecting "press Option key" via the menu in either has no effect. From what I've learned, this is an error in Basic that you can avoid on a true Atari unit by pressing and holding the "Options" button during boot 

 

Altirra/x64 - worked flawlessly without touching any settings.  Select the rom image, and off you go, playing the game.

 

So whatever base options/settings that are built into Altirra/x64 to make this particular game work, don't appear to be available in either lr-Atari800 or Atari800win on a side-by-side comparison.

 

So my question is... Why does this error display on only this game and what can I do about it...if anything?  If I had the actual system, how would I play this game with this error?  

 

I'm a long-time emulation user, Retropie, Vice...MAME.. etc.  I usually can get odd-ball issues like this to work.  But this one has me stumped and kinda dissapointed.  I'd love to be able to play this on the Atari system as I did at my buddies house back in 1984.  

 

Thanks for your help.  I hope I reached out to the right place.  I'm just out of ideas....and understandably have gotten no response from the Retropie forum on this.  

 

Best,

 

JR

Edited April 15, 2021 by IMBerzerk

[+DjayBee]

This looks like a copy protection issue.

Protection on this title is timing based and usually not effective in emulation because the timing differs from real hardware. I guess that due to whatever it is effective with Retroarch.

 

Try this crack:

Computer Ambush v1.2 (1984)(SSI)(US)[cr CSS].atr

[phaeron]

You can also resave the disk as ATX from Altirra, which will bake in the sector timing that Altirra uses for ATR images into the ATX image. Atari800 should then boot it.

 

[IMBerzerk]

Thank you both for the help.  I'll give each at try and use that method for any other game I see this on.  

 

I remember SSI had some crazy protections later on, but I didn't think this title had anything.

[IMBerzerk]

Got it!!  That worked!  Thank you very much!