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Trifox
Account closed
Registered: Mar 2006
Posts: 108 |
question about triggered raster line in raster interrupt
i am using this code
to initialise my interrupt
this should look fairly common:
(pasted from somewhere ... )
; Initialise Music Interrupt
sei ; turn off interrupts
lda #$7f
ldx #$01
sta $dc0d ; Turn off CIA 1 interrupts
sta $dd0d ; Turn off CIA 2 interrupts
stx $d01a ; Turn on raster interrupts
lda $d011
;ldx #%1000
;ldy #$14
and #%01111111
sta $d011 ; Clear high bit of $d012, set text mode
;stx $d016 ; single-colour
;sty $d018 ; screen at $0400, charset at $2000
lda #<int ; low part of address of interrupt handler code
ldx #>int ; high part of address of interrupt handler code
ldy #0 ; line to trigger interrupt
sta $0314 ; store in interrupt vector
stx $0315
sty $d012
lda $dc0d ; ACK CIA 1 interrupts
lda $dd0d ; ACK CIA 2 interrupts
asl $d019 ; ACK VIC interrupts
cli
to init my interrrupt, i encountered that this interrupt is triggered in row 256 :( what must i do to let it trigger on exactly line 0 ? and only there, not on line 0 AND 256 ... know what i mean ?
i am leaving the interrupt with following fragment:
; Initialise Music Interrupt
sei ; turn off interrupts
lda #$7f
ldx #$01
sta $dc0d ; Turn off CIA 1 interrupts
sta $dd0d ; Turn off CIA 2 interrupts
stx $d01a ; Turn on raster interrupts
lda $d011
;ldx #%1000
;ldy #$14
and #%01111111
sta $d011 ; Clear high bit of $d012, set text mode
;stx $d016 ; single-colour
;sty $d018 ; screen at $0400, charset at $2000
lda #<int ; low part of address of interrupt handler code
ldx #>int ; high part of address of interrupt handler code
ldy #0 ; line to trigger interrupt
sta $0314 ; store in interrupt vector
stx $0315
sty $d012
lda $dc0d ; ACK CIA 1 interrupts
lda $dd0d ; ACK CIA 2 interrupts
asl $d019 ; ACK VIC interrupts
cli
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yago
Registered: May 2002
Posts: 333 |
While we are at it...
dont use dec $d019, or asl $d019 or similar..
Please use
lda $d019
sta $d019
makes sure to stay compatible with e.g. c65.
Thanks in Advance,
Zed
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tlr
Registered: Sep 2003
Posts: 1790 |
Quote: While we are at it...
dont use dec $d019, or asl $d019 or similar..
Please use
lda $d019
sta $d019
makes sure to stay compatible with e.g. c65.
Thanks in Advance,
Zed
I always used lda #$01/sta $d019 in my stuff, but I've never seen anybody use lda $d019/sta $d019.
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Trifox
Account closed
Registered: Mar 2006
Posts: 108 |
whao, thanks for so much information |
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Mace
Registered: May 2002
Posts: 1799 |
Why would I want to make my stuff compatible with C65?
I'd have to stick to all compatibility rules then, and I didn't even _know_ there was the possibility to do so :-)
BTW, what _are_ the (other) rules to keep C64 compatibility? |
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MagerValp
Registered: Dec 2001
Posts: 1078 |
WTF? CSDB just deleted my post and gave me a search page instead.
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WVL
Registered: Mar 2002
Posts: 902 |
Right. Like most demos are not compatible with c64 because of ASL $d019.. :) I'm guessing 99.9% of demos wouldnt run anyway, because of
-vic trickery
-illegal opcodes
-lotsa other stuff
So please keep saving those cycles and do ASL $D019 ;) |
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Oswald
Registered: Apr 2002
Posts: 5094 |
looks like I'm alone with my lsr $d019 :) |
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chatGPZ
Registered: Dec 2001
Posts: 11386 |
inc $d019 ftw! |
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Scout
Registered: Dec 2002
Posts: 1570 |
Quote: looks like I'm alone with my lsr $d019 :)
Nope :) |
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Graham
Account closed
Registered: Dec 2002
Posts: 990 |
SRE $D019 |
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