Meteor Storm (Compute! Issue 29) - Fixed for XL/XE

I've been messing around with magazine type-in games again these last few weeks, at the minute I'm on Compute!.

I came across Meteor Storm and couldn't get it working under XE OS. Tried all sorts but it wasn't happening. MC was the only way, but my MC-fu is weak. Several hours later and I've found a memory move routine that works backwards (necessary in this case). Several more hours later and I've got it working after figuring out how to do addition in MC (very painful). A couple more hours and I've integrated it into the game and it is working fine, to my eternal joy.

Fix notes:

This game refuses to work on XL/XE systems as originally printed. The reverse
scroll of the meteors is achieved by fooling the OS into thinking it is in mode
0 when it is actually in mode 1, and then printing an insert line character at
the top of the screen. While this works on the 400/800 OS, under the XL/XE it
does something evil to the display RAM, corrupting it and making the game
unplayable.

To fix this, I have added a small MC routine to replace the print of the insert
line character. The MC routine detects the address of the start of screen RAM,
and copies lines 23-3 to the next line down in reverse order. A normal memory
move wouldn't have worked as the source and destination overlap.

And here they are; bootable ATR (Basic required), and the BAS and LST (as a TXT) files for your pleasure. Enjoy!

PS, Atarimania are more than welcome to add this to their database as a fixed version.