Re: [stella] VDEL on missiles

Subject: Re: [stella] VDEL on missiles
From: Erik Mooney <erik@xxxxxxxxxx>
Date: Sun, 26 Aug 2001 09:24:23 -0400
>Why exactly is there no VDEL function on missiles, but there is VDEL on the 
>If VDEL effects missiles based on the VDEL of their players, then how would 
>you independently control their Y position, just by enabling or disabling 
>the missile on that exactly scanline?

Recall that VDEL for the players doesn't have anything to do with any
vertical timing.  If VDELP0 is set, any write to GRP0 does not take effect
until you do a write to GRP1.  In a two-line kernel that updates one
player per line, the effect is that VDELPx gives a one-line delay as in

So I really have no idea how VDELBL works.  Anyone else?

Archives (includes files) at
Unsub & more at

Current Thread