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Forums > C64 Coding > $D3 behavior: values over $27. Why?
2012-10-23 04:26
Flavioweb

Registered: Nov 2011
Posts: 463
$D3 behavior: values over $27. Why?

Take this code:
.> c000 a9 ff     lda #$ff
.> c002 8d 13 c0  sta $c013
.> c005 a9 20     lda #$20
.> c007 ce 13 c0  dec $c013
.> c00a f0 06     beq $c012
.> c00c 20 d2 ff  jsr $ffd2
.> c00f 4c 05 c0  jmp $c005
.> c012 60        rts

set a breakpoint to $c00c.
Check $D3 for current cursor column.
Why there are values over $27 ?

2012-10-23 07:38
MagerValp

Registered: Dec 2001
Posts: 1078
Because there are 80 characters in a line.
2012-10-23 07:40
Skate

Registered: Jul 2003
Posts: 494
i tried it and $d3's value is zero here. and cartridges or other routines involved at your test platform?
2012-10-23 09:08
Wisdom

Registered: Dec 2001
Posts: 90
The number of characters in a logical line can be either 40 or 80. Check $00D5 for current logical line length.
2012-10-24 07:07
Flavioweb

Registered: Nov 2011
Posts: 463
There is a way to set virtual line lenght always to $27?
Setting $D5 also after PLOT call seems don't work.
Something related to screen area hi bytes in $D9-$F1?
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