Re: [stella] Z26 vs. Oystron

Subject: Re: [stella] Z26 vs. Oystron
From: Piero Cavina <p.cavina@xxxxxxxxxxxxx>
Date: Mon, 19 Jan 1998 12:26:53 +0100 (MET)
At 09.05 18/01/98 -0800, you wrote:

>>Today, trying Z26 for the first time (a 32K program?!... wow!), I've
>>noticed that Oystron is almost unplayable, because the player is always
>>killed by the pearls flying in the 8th row (counting from the top). Please
>>do something..! :-)

>I was wondering, the column of dots down the middle of the screen is also
>missing.  What are they?  Players?  Any chance I could see the code that
>generates the lines with the dots in them?

They're Missile 1. Here's the part of the kernel that takes care of them.
(it's from release 2.8.5 as I haven't the latest here, but it shouldn't have
changed)
Sorry, you'll have to do the cycle-counting by yourself, as I was too lazy
to do it when I wrote that code.. :-)

>       STA    WSYNC
>
>; -----------------------
>
>       STA    HMOVE <--- we were positioning P1 in the previous scanline
>       LDA    #%00001100 <----- two copies wide and a decent color, in the
same byte :-)
>
>       STA    NUSIZ1 
>       STA    COLUP1
>
>       LDA    TEMP+5 <-------- TEMP+5 is always 0 in the first row, we
don't want the dots there
>       STA    ENAM1 <------- turns on the dots
>
>       LDA    LINESTATUS,Y
>       BPL    VVV
>       TXA    ;0
>VVV:
>       AND    #%10111111
>       TAX
>       ASL
>       adc    ANIMAT
>       TAY
>       LDA    GRPOIN,Y
>       STA    GRPPNT
>
>       LDA    NMYCOLOR,X
>       STA    TEMP      
>       STA    COLUP1 ;* <--- I bet we've already drawn the 2nd copy of M1
>
>       LDX    #0
>       STX    CXCLR  ; X=0
>
>       LDY    GRPCOUNT
>       LDA    NUSIZE,Y
>       STA    NUSIZ1  <---- for P1 in the next scanline
>
>       STX    ENAM1 <-------- turns off the dots before it's too late
>       STA    WSYNC
>
>; -----------------------
>       LDX    PLOFF
>

P.




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