Oh. Well, good for z26! :)
So...with that in mind, things should look like this:
(pictures helps me to not get confuzzled)
line 258: active video
line 259: active video
line 260: VBLANK
line 261: VBLANK
line 262: VBLANK
line 001: VBLANK VSYNC
line 002: VBLANK VSYNC
line 003: VBLANK VSYNC
line 004: VBLANK
line 005: VBLANK
line 006: VBLANK
line 007: VBLANK
line 008: VBLANK
line 009: VBLANK
line 010: VBLANK
line 011: VBLANK
line 012: VBLANK
line 013: VBLANK
line 014: VBLANK
line 015: VBLANK
line 016: VBLANK
line 017: VBLANK
line 018: active video
line 009: active video
...
...
-Chris
On Sat, 26 Mar 2005, Zach M wrote:
> Ok, I misunderstood before.
>
> FYI, I've been refering to lines by their number starting at 1, not 0,
> because that's how the z26 trace log does it.
>
> >From: Chris Wilkson <ecwilkso@xxxxxxx>
> >Reply-To: stella@xxxxxxxxxxxxxxxxxx
> >To: <stella@xxxxxxxxxxxxxxxxxx>
> >Subject: RE: [stella] 262 scanline kernel is rolling
> >Date: Sat, 26 Mar 2005 21:17:50 -0500
> >
> >Wait...
> >
> >What I meant was you should turn on VSYNC 3 lines after you turn on
VBLANK.
> >So when are you turning on VSYNC? Assuming you're numbering your lines so
> >that the first line of VSYNC is line 0, (that's what most of the docs
> >around
> >here say to do) then you should turn on VBLANK at the beginning of line
> >259.
> >It would then be on for lines 259, 260, and 261. Then VSYNC comes on at
> >the
> >beginning of line 0 (= line 262) and turns off at the beginning of line 3.
> >
> >Is this equivilent to what you meant?
> >
> >-Chris
> >
> >On Sat, 26 Mar 2005, Zach M wrote:
> >
> > > I just tested a few minutes ago, and the screen does not roll anymore.
I
> >had
> > > made the changes Dennis suggested, and also turned on VBLANK at line
261
> >as
> > > Chris had recommended. So it is hard to say exactly what the problem
> >was.
> > > The reason I suspect it had something to do with writing 8 to VBLANK is
> > > because an earlier version of the kernel did not roll, and there #$42
> >was
> > > written to VBLANK (just like in"Our First Kernel"). The "lda #$42" line
> > > before "sta VBLANK" was inadvertenly removed at some point.
> > >
> > > I might do more experiments with writing 8 to VBLANK if there is enough
> > > interest.
> > >
> > > >From: "Dennis Debro" <dennis@xxxxxxxxxxxxxxx>
> > > >Reply-To: stella@xxxxxxxxxxxxxxxxxx
> > > >To: <stella@xxxxxxxxxxxxxxxxxx>
> > > >Subject: RE: [stella] 262 scanline kernel is rolling
> > > >Date: Sat, 26 Mar 2005 14:49:35 -0500
> > > >
> > > >Hi there,
> > > >
> > > > > Right now you're writing 0 at the start of vertical blank
> > > > > and 8 at the start of overscan.
> > > >
> > > >That is strange. As Thomas said, D1 of VBLANK only controls the TIA
> >output.
> > > >At least as documented by the programming manual. So writing 8 to the
> > > >register is essentially the same as writing 0 (i.e. enabling TIA
> >output).
> > > >
> > > >I don't have my hardware setup at the moment to play with this. Was
> >this
> > > >truly the problem? What happens if you used other values or ignored
> >VBLANK
> > > >altogether? By the values you were entering this should have been
> > > >simulated.
> > > >Are there other bits used by VBLANK that we don't know about?
> > > >
> > > >Take care,
> > > >Dennis
> > >
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