Millipede scoring problem

[DEBRO]

Thought share after discovering this while attempting to reverse engineer Millipede.

 

The player is supposed to score 3X the point value when the object is destroyed with a DDT cloud. There is a mistake in Millipede that has the player score 30 points for destroying the Millipede head in the DDT cloud or 300 points for destroying the Millipede body segment in the DDT cloud.

 

The issue can be found in BANK1. The instruction at $B325 should be BPL instead of BMI. This will drive the scoring of destroying the Millipede head to be 300 and the Millipede body segment to be 30 as it should.

Edited March 22, 2022 by DEBRO

[Thomas Jentzsch]

Good find! Did anyone notice this before?

[Tempest]

Is this for the Atari version or the GCC prototype?

[DEBRO]

17 hours ago, Thomas Jentzsch said:

Good find! Did anyone notice this before?

I had never heard of this before. I searched once I found the issue to see if anyone had reported or recognized it.

16 hours ago, Tempest said:

Is this for the Atari version or the GCC prototype?

This is in the Atari version. I hadn't looked too deeply into the GCC prototype yet.

 

I'm assuming Dave may have had the source code to Centipede or notes from the project. Some of the bit masking values are the same as well as some code such as breaking the Millipede chain. The mistake here was thinking D7 being set meant the Millipede segment was a head. I would've thought the same as to give it similar behavior to a poisoned mushroom.