[stella] cosmic ark stars missile 1

[Manuel Rotschkar]

Hi Andrew!

TJ seems to recommend MESS lately for proper execution of these kind of  
tricks.

Greetings,
Manuel

> Strange.  If I use this code I don't get stars.  If I change it to  
> missile 0
> I do get stars.  Is Stella (the emulator) confirmed to work with the star
> effect with missile 1? I don't have hardware setup to test this.
>
> Cheers
>
> A
>
>
>
>
>   _____
>
> From: stella-bounces at atari2600.org [mailto:stella-bounces at atari2600.org]  
> On
> Behalf Of Darrell Spice, Jr.
> Sent: Wednesday, January 16, 2008 2:15 AM
> To: Atari 2600 programming list
> Subject: Re: [stella] cosmic ark stars missile 1
>
>
> I used M1 to generate the stars in Stay Frosty.
>
>
>           ldx #$70
>
>           stx HMM1
>
>           sta WSYNC
>
>           sta HMOVE ; 3
>
>           SLEEP 16 ; 16 19
>
>           dex ; 2 21
>
>           stx HMM1 ; 3 24 ; this confuses the TIA and generates stars :-)
>
>
> values are $7x and $6x for the 2 HMM1 hits.
>
>
>
> On Jan 15, 2008, at 7:17 AM, Andrew Davie wrote:
>
>
>
>
>
> I don't understand the magic behind cosmic ark stars, but I am using it
>
> successfully for Boulder Dash to give the extra-life shimmer. However,  
> the
>
> code I use is using missile 0 and I really want to use missile 1. But  
> when
>
> I change things from missile 0 to missile 1, I no longer get 'stars';  
> just
>
> 'stripes'. In other words the effect doesn't work. I'm pretty sure it's  
> to
>
> do with the magic numbers in the following code. I just don't know what
>
> magic numbers to use for M1 (or for ball). Can anyone help?
>
>
> jsr rndm
>
> and #7
>
> clc
>
> adc #4
>
>
> TAY
>
> ; STA WSYNC
>
> .r22 DEY
>
> BPL .r22
>
> STA RESM0
>
> LDA #$70 ;this value is important for the
>
> effect
>
> STA HMM0
>
>
> STA WSYNC
>
> STA HMOVE
>
> JSR Trick2 ;waste 18 cycles and load move
>
> value
>
> STA HMM0 ;this is the tricky part
>
>
>
> LDA #$02 ;turn missile0 on
>
> sta WSYNC ; 3
>
> STA ENAM0
>
>
> rts
>
>
> Trick2: NOP ;the tricky subroutine
>
> NOP
>
> LDA #$60
>
> RTS
>
>
>
> The above gives a reasonable random effect for me. If I change the lda  
> #$60
>
> then it stops working. If I change to missile 1, it stops working.
>
>
> Could someone please analyse this and/or suggest the correct values?
>
>
> Thanks
>
> A
>
>
>
>
> _______________________________________________
>
> Stella mailing list
>
> Stella at atari2600.org
>
> http://atari2600.org/mailman/listinfo/stella
>
>
> Darrell Spice, Jr.
>
> darrell.spice.jr at spiceware.org
>
>
>
>



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