How to crack games on the Atari 800 XL !

Many games by LK Avalon had a weak protection that could easily be broken...

Description of "protection-format 1":
The game is already in standard file format, but the sectors that contain DOS informations are deleted. A file-copy using a normal DOS is impossible. There is a special little boot program (not bigger than 3 sectors) written to the disk that asks for a protected sector (to make sure disk is the original). After verifying the disk, the boot-code continues to load the game...

That's all !

How to crack a game with the above protection :
1. Make a backup of your original disk, ignoring all errors that appear.
2. You can try a good "fixdisk" program.
(If this does not work you have to write the DOS information in sector 361 (hex: $169) by yourself.)
3. After successful hacking, just copy the game-file from the backup-disk to your favorite menu-disk.

Example:

Change by LK Avalon :

(protected sector was 989 / $3DD)
 Here you can find a disk-image of "Change".
Before you can play the game you have to de-protect it... ;-)
Remember that most games won't run from a DOS, so you have to use a game-DOS !
If you want to make a backup of your original boot-disk, you need to remove the bad-sector check.
Here's a small utility I wrote that does the job for you !!!
1) Just copy your original disk, ignoring all bad sectors (diskcopy of Turbo-DOS will be fine, as you can select to quit on empty sectors)
2) Check your copy with "Avalon Boot 2K1" and write new boot code ! There is still no guarantee that this will work on all games ! ("Imagine", for example, has a 2nd error-check within the file !)
3) Never use the original disk. Use "Avalon Boot 2K1" only for your personal backups !!!
click here to download "Avalon Boot 2K1"

Here's another protection technique:

Many games jump to Self-Test or reboot if there is no protected sector on the disk.
And if the game isn't packed - you'll have a good chance to crack it. But remember never use the original !
So, what do you have to do ?

1) Grab a decent sector editor with search function (Happy Master will be fine) and search for a) or b) :
a) "4C 71 E4" , that means : jmp $E471 (...jump to self-test)
b) "4C 77 E4" , that means : jmp $E477 (...do reboot)
2) Replace it with "EA EA EA", that means 3-times "nop" (do no operation)

There is still no guarantee that this hack will work - but it works with many games from "Krysal Software" or "Sikor Soft" !