Re: [stella] Need Help with 13 - character display routine.

Subject: Re: [stella] Need Help with 13 - character display routine.
From: Christopher Tumber <christophertumber@xxxxxxxxxx>
Date: Wed, 10 Dec 2003 19:52:56 -0500
R Mundschau wrote:

>The first time I tried this routine, I used writes to RESBL to a shadow copy of the register outside of zero-page.  The plan was each write would take 4 cycles * 3 color >clocks = 12 pixels = the desired width.  Then all the RESBL writes could be packed together.  It made the routine very clean and it used fewer cycles because I could set >P1 to quad and get 3 columns from it.  Stella for Mac did not like it at all, however, I just got a black screen.  So I rewrote the routine to use the zerpage  instances of >RESBL.  I could have set X to 0 and said STA RESBL,X to get 4 cycles, but I wanted to use X for other purposes.  So A staggered the use of the ball through the 14 >columns so there is always at least one non-ball column between 2 ball columns.

You could do:

STA.w RESBL (Equivalent to STA $0014 -> It's absolute addressing, not zero page)

Since many of the old games use this kind of addressing, Mac Stella should handle it.


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