Hey all, I'm having more trouble understanding "Making Games for Atari 2600".  This time, chapter 9, page 53, the section below, for anyone who knows it: A now contains (the remainder - 15). ; We’ll convert that into a fine adjustment, which has ; the range -7 to +8. eor #7; this calculates (23-A)% 16 asl asl asl; HMOVE only uses the top 4 bits, asl; so shift left by 4 sta HMP0; set fine position That tricky calculation with EOR and ASL converts the remainder into a value appropriate fo