RE: [stella] Re: About your tutorial

Subject: RE: [stella] Re: About your tutorial
From: "Lee Fastenau" <stella@xxxxxxxxxxxxxxx>
Date: Mon, 12 Apr 2004 08:06:13 -0500
> But as I'am currently trying to write a source code
> that I'll use as the basis structure of all my future
> programs, I'am trying to be very accurate into cycle
> couting for each portion of the code, so I'll be able
> to say exactly how many cycles will be available for
> the Verticlal Blank or Overscan periods without care
> about all the instructions I already wrote for timer
> programming and other stuff.

There really isn't much need for cycle counting in your vblank and
overscan... for a couple of reasons.  First, there's actually quite a bit of
elbow room, cycle-wise, in those areas.  If your goal is to produce 2 or 4K
programs, you could easily run out of space before you run out of cycles.
Second, you could spend a LOT of time counting cycles in your vblank and
overscan code, and it may often be impossible due to complex loops and

If your game kernel begins to "twitch" or behave oddly and you suspect
you've overrun the cycles, backtrack a little bit and try to rule out a few
other things like page boundary crossing or, as I recently experienced, an
errant loop structure.

> (I'll write one for NTSC and one for PAL and
> I'll post them at Stella Big List as soon as they will
> be finished, so 2600's gurus like you will be able to
> correct me)

I began cutting my teeth on some templates right before diving into my first
game (which I'm still cutting my teeth on).  They helped me visualize how
VCS programs flow, but I found that templates are not nearly as valuable as
I once thought.  It's not like Windows programming, where you need a ton of
framework just to do the simplest task.  Once you start writing a game,
you'll see what I mean.

As for NTSC vs. PAL, why not support both at the same time? :)


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