Another Berzerk discovery...at least for me :-)

["Dennis Debro" <dennis@xxxxxxxxxxxxxxx>]

Hi there,

I was looking at Berzerk again and I see Dan used fractional positioning
to help keep the game speed consitent between NTSC and PAL :-)

This is the first game I've disassembled see do this.

Here is the player movement code...

   lda playerMotion                 ; get the player's fractional delay
   clc
   adc #PLAYER_FRACTIONAL_DELAY
   sta playerMotion
   bcc LF42C

PLAYER_FRACTIONAL_DELAY is 112 for NTSC (i.e. 7*256 / 16 -or- move 7 out
of 16 frames) and 134 for PAL (i.e. [7*256 / 16] * 1.2 adjusted for 50
frames per second).

He does fractional positioning for the missile movement too.

I'll try to push to finish this listing quickly because it's pretty nice
and I'd like to share it.

Take care,
Dennis