Re: [stella] Qb: v0.03

Subject: Re: [stella] Qb: v0.03
From: Kurt.Woloch@xxxxxxxxx
Date: Thu, 15 Feb 2001 08:25:44 +0100
Andrew Davie wrote:

>You might notice the dual 6-digit displays (top/bottom).  These are done
>using the one routine (including the colouring).  You pass a colour
>to the routine, and it shades the digits with that.  Works well.  Look at
>the routine "ScoreLine"...  source is included in the file.  I
>just a few cycles short of making it into a dual-purpose
>double-height/single-height routine, but I ran into a situation where I
>really DID need to waste just one cycle, and couldn't do it.

>Something like this...

>    sty loop                ; 3
>   bcs SingleLine    ; 2(3)
>   >> need to waste ONLY ONE cycle here
>        lda (S0),y ;5
>        sta GRP0                ; 3 = 15

>Can't change the sty to a sty.w, as there's no free cycles when you branch
>to SingleLine (that is, you can only use 5 cycles before THAT section has
>start, and they're taken with the sty).  Furthermore, you HAVE to have the
>sty first, as it's buggered pretty much immediately.  Anyway, this is an
>example where a single-cycle delay is needed.  I tried, and failed :)

OK, so... do you have to wast the cycle BEFORE the lda (S0),y? I don't
suppose so, since typically only WRITES are critical. The next write would
be the sta GRP0. If you replace that with sta.w GRP0 (if that works), I
think you would end up with the thing taking up one more cycle and thus GRP0
written one cycle later. I guess that's what you wanted, wasn't it?

>As usual, comments and suggestions most welcome.

Well, I didn't want to comment on it before having seen the original Atari
800 version (since you're also the original author of that one)...
and I got into some problems trying it out... strangely the "" file
won't unzip when I try it with PKUNZIP (for I don't have Winzip on my PC at
home)... maybe it'll work with Winzip... we'll see.

Concerning the poll:
I don't do any 2600 programming at the moment, but my time's mainly taken up
doing the following things:

1. Playing concerts with my partner Franz (we have got 8 concerts this
month!) and rehearsing for them
2. Updating my homepage at
3. Doing a weekly show at our local community radio station, and writing
some MP3 sorting and handling programs for it
4. (if there's time left) trying to put together a CD+G editor (CD+G being
another strange format, like a 2600 program...)

With love (and many programs to write)
Kurt Woloch


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