Re: [stella] GunFight 2600: Limit broken again! Now help needed! :-)

Subject: Re: [stella] GunFight 2600: Limit broken again! Now help needed! :-)
From: Manuel Polik <manuel.polik@xxxxxxxxxxx>
Date: Fri, 16 Feb 2001 14:53:49 +0100
Eckhard Stolberg wrote:

> > And: can someone give me a crash course in clever missile programming? I
> > mean, do I really have to tweak ENAMx all the time? what about just
> > making the missile invisible with the background color?
> As long as there is nothing above or below the cowboy, you can disable
> the missile by changing it's colour. But if you try to make the
> background more interesting by adding some playfield graphics for
> example, a recoloured missile would stand of against the playfield,
> if you don't turn it off properly with ENAMx.

I have to consider this... All depends a bit on how many cycles I can
free with a 2LK. At the moment I just see that I win nothing in the
color-writes. I'd have to do 4 writes in each line, gaining only few
cycles by buffering these values.
> If we call the registers GRP0-A, GRP0-B, GRP1-A and GRP1-B,
> then the graphics work like this. The A registers are what
> you write to when you store something to GRPx. But when you
> for example do STA GRP0, not only gets the contend of the
> accumulator copied to GRP0-A, also the contend of GRP1-A
> gets copied to GRP1-B. With STA GRP1 you also copy the
> contend GRP0-A to GRP0-B.
> VDELx lets you select, if you want to display GRPx-A or
> GRPx-B.

So all graphics are just shifted one line down. And what's the gain?
If I understand that right, you have still to do the right timing, then
starting from the second write, or?

What I have in mind ATM is one line with data
calculations/fetches/bufferings(and color writes *sic*) and a second
line with writes. This'd help more than delaying, or?


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