• An analysis of the original Polar Rescue cartridge and source code
  

Project Status

• Digital Archeology - An investigation of the Polar Rescue cartridge

• After discovering the Easter Eggs (programmer's name) in Star Ship (see here) and Spinball (see here), I took a look at yet another game written by Mark Indictor.

• I recall that at some point in the past, someone on the web mentioned that he saw Mark's name appear on the screen when playing Polar Rescue, but that someone also wrote that they did not know why it showed up and could not reproduce this.
  

• I did not succeed in finding that post, so it might not be available anymore, but as it turned out that person was right. There is such an Easter Egg in Polar Rescue.
  

• Polar Rescue was coded by Mark Indictor, and as in his other games he again coded a mechanism to make his credentials appear in the screen.

• As it turned out, the method to trigger this is rather easy, but it was very well hidden and obfuscated inside the code.
  

• When you finish the game, and the "GAME OVER" message appears on the screen, then simply press button 4 on controller 2, and the M.INDICTOR will appear at the bottom of the screen:
  

• The Polar Rescue code reuses the GAME OVER message which is stored inside the Mine Storm code in the BIOS. It also uses a custom print routine for printing strings. This routine, when detecting the end-of-string-indicator, checks bit 1 of the interrupt-flag vector. And this bit is directly connected to button 4 of controller 2. Took me a while to figure this out and to understand the mechanism, but the investigation was fun, and I really enjoyed this treasure hunt. Thanks Mark!
  

• To be continued...
  

• Again, this analysis would not have been possible without Vide.
• Many thanks to Malban for once more adding tons of new features I suggested or asked for.