Re: [stella] 6 digit score display and other ramblings

Subject: Re: [stella] 6 digit score display and other ramblings
From: emooney@xxxxxxxxxxxxxxxx (Erik Mooney)
Date: Mon, 16 Mar 1998 04:09:53 GMT
>> The standard routine (don't think there IS any other, since the standard
>> does it with no cycles to spare) uses the 12 bytes for the pointers plus
>> one for temp storage.  You can store the score data any way you like and
>> set up the pointers during vblank.  I'd probably recommend 3 bytes of BCD.
>Hmm, I'm still doing a wsync on each line... perhaps I should transfer
>the source/binary over (a bit of a hassle, since it's on the 64) and
>let you folks have a look.

The standard does a wsync on each line too, but it uses every one of the
other 71 available cycles.  If we could get a look at your source, it'd be

> It uses indirect indexed addressing, so it has to use LDA for the loads...
>> for temp storage, STA zeropage / LDA zeropage is the same speed as
>> TAX/TXS/TSX, with the added flexibility of letting the load be into any of
>> the registers.
>No - tax/txs/tsx etc only take 2 cycles, while LD?/ST? zero page take 3.
>This is why I used the stack pointer as the extra - saved one cycle...

3 instructions * 2 cycles = 2 instructions * 3 cycles, last I checked :)
If you're somehow doing a LDX instead of LDA, the stack-pointer method is

>> Well, there's the old movable-sprite deal, if you haven't done that yet.
>You mean just a sprite moving around under joystick control?  Yes, that
>was my first program.

I think it was for everyone, except me... I moved from "How to Draw a
Playfield" straight into the early stages of INV, spending quite a while on
playfield kernel before adding the players.

>> multiple-sprite package.  Or you could try to make your score routine into
>> a movable 48-pixel sprite... if you can do that, we'll be groveling at your
>> feet :)
>:)  48-pixel sprite, that can be positioned anywhere? :)  I'll have to
>try ;)

If you can, we'll love you for life :)  (Did anyone even get a 32-pixel
movable sprite to work?  With color changes?  Using wsyncs?)

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