Posted By
rudis
on 2012-01-15
14:03:43
 |  ca65 lowbyte
played little bit with asm
--8<---
.setcpu "6502"
.org $1001
.word *
.word link
.word 2012 ; zeilennummer
.byte $9e ; sys-token
.byte "4109" ; adresse
.byte $00 ; zeilenende
.byte $00,$00
link:
sei
ldx #<myvbl-2
stx $312
ldx #>myvbl
stx $313
cli
rts
myvbl:
inc $ff19
jmp $ce42
jsr $fff6
-->8--
so if i don't write
ldx #<myvbl-2
but
ldx #<myvbl
the adress is 2 bytes to high. WHY???
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Posted By
gerliczer
on 2012-01-15
14:19:19
| Re: ca65 lowbyte
Is it any better if you try it with
.org $ffe
.word $1001 ?
Anyway, I think you should move the label "link" before the line ".byte $00,$00" because the way it is written now makes the basic line linking wrong. At least I think so.
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Posted By
siz
on 2012-01-15
14:29:24
| Re: ca65 lowbyte
Gerliczer is right: you put the load address (.word *) after your .org $1001 and that shifts the rest of your code by two bytes.
So you should write:
.org $1001 -2 (which is $fff and not $ffe  )
.word $1001
...and the rest
Also gerliczer is right in case of the placement of the link label too.
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Posted By
rudis
on 2012-01-15
15:01:10
| Re: ca65 lowbyte
works like a charm now.
many thanks
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Posted By
gerliczer
on 2012-01-15
16:21:03
| Re: ca65 lowbyte
Half an hour later I realized too that the correct address for the .org directive should be $fff. siz was much quicker than me. Another idea would be leaving it as rudis wrote it originally and inserting a .org *-2 line after the load address word. This works only if the compiler supports such syntax and more than one .org directive in one source.
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