Subject: Re: [stella] 262 scanline kernel is rolling From: "Zach M" <zach_in_sac@xxxxxxxxxxx> Date: Sat, 26 Mar 2005 01:17:47 -0500 |
Thanks Aaron. I believe that VBLANK was the problem in my kernel. One thing I'm confused about though: Should VBLANK be set at the start or the end of overscan? I just used z26 to trace the code of Pacman and Outlaw, and it appears they set VBLANK at scanline #263. >From: "Aaron" <stella-receiver@xxxxxxxxxxxxxxxxx> >Reply-To: stella@xxxxxxxxxxxxxxxxxx >To: stella@xxxxxxxxxxxxxxxxxx >Subject: Re: [stella] 262 scanline kernel is rolling >Date: Fri, 25 Mar 2005 21:24:45 -0500 > >Zach M said: > > Hello all, my first homebrew kernel looks good in emulators, and z26 > > reports > > that it displays 262 scanlines, but when I test on a TV the image rolls > > slowly, almost like a scrolling background in a Xevious-type game. > >It doesn't look like you're using VBLANK (the TIA register) correctly. >You should turn it off (write 0) at the start of the visible screen, then >turn it on (write 2) at the start of overscan and leave it on throughout >vertical blank. Right now you're writing 0 at the start of vertical blank >and 8 at the start of overscan. > >I'm in a similar situation with my game (works fine in emulators, rolls >badly on a real machine) and this was one of the first things I checked... > >-Aaron > >Archives (includes files) at http://www.biglist.com/lists/stella/archives/ >Unsub & more at http://stella.biglist.com > _________________________________________________________________ Express yourself instantly with MSN Messenger! Download today - it's FREE! http://messenger.msn.click-url.com/go/onm00200471ave/direct/01/ Archives (includes files) at http://www.biglist.com/lists/stella/archives/ Unsub & more at http://stella.biglist.com
Current Thread |
---|
|
<- Previous | Index | Next -> |
---|---|---|
RE: [stella] 262 scanline kernel is, Dennis Debro | Thread | Re: [stella] 262 scanline kernel is, Aaron |
Re: [stella] 262 scanline kernel is, Aaron | Date | Re: [stella] 262 scanline kernel is, Aaron |
Month |