Re: A86: contrast
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Re: A86: contrast
Well that didn't work so i tryed something like this...and it didnt
work.....what have i done worng? ld a,($c008)
ld a,($c008)
ld l,a ;ld hl,a
ld h,0
call UNPACK_HL
add a,'0' ;make it ascii
ld (con),a
ld hl,con ;now hl pints to contrast
call _vputs ;but its putting out a blank
;saw it done in kollums.asm
con:
.db $00,$00
>First of all, when using pen coordinates (PenCol, PenRow) you need to
>remember that each row is a pixel wide, so instead of displaying your
>second line output at row $01, you should use $06. (each line of text is
>6 pixels high).
>
>ld bc, $0600 instead of ld bc, $0100
>ld (_penCol), bc
>
>Second, you are attempting to display a number using _vputs. _vputs
>displays the text beginning at the memory location POINTED TO by the HL
>register. You loaded the contrast value into HL, and tried to use
>_vputs to display it. It outputted garbage on the screen because _vputs
>went to the location in HL, which would have been some address between
>$0000 and $00FF (you loaded 0 into h). When it got there, it displayed
>characters until it encountered a $00 byte. That is why it displayed
>garbage. I believe someone else replied saying that you should use the
>dispAHL routine. You may be able to use this, but I'm not entirely sure
>it functions... my emulator's dead, and my link doesn't work, so if
>someone could tell me it does or doesn't work as planned it would be
>appreciated.
>
>;DispHLvwidth displays HL as a number in variable-width font
>;--------------------------------
>;input: - value in HL do display
>; - graphscreen coords in bc
>;output: - HL displayed in vWidth font
>; - OP1-3 used
>;--------------------------------
>
> ld (_penCol),bc ;cursor location in bc
> call _SetXXXXOP2 ;OP2=hl
> call _OP2TOOP1 ;move to OP1
> call _formreal ;OP3=zero-terminated string value of
>OP1
> ld hl,_OP3 ;point hl to OP3
> call _vputs ;display
> ret ;return
>
>Cassady Roop
>croop@oregontrail.net
>
>
>Andrew T wrote:
> >
> > hmmmm I made a little contrast program but i am haveing some problems
>could
> > some one tell me two things, first im getting trash in my out put second
>you
> > cant hold down a key you have to keep on pushing it.
> > BUT...i am happy to say that it does make the contrast go up or down
> >
> > .org _asm_exec_ram
> >
> > ProgStart:
> > ld bc,$0000
> > ld (_penCol),bc
> > ld hl,msg
> > call _vputs
> > ld bc,$0100
> > ld (_penCol),bc
> > ld a,($c008)
> > ld l,a
> > ld h,0
> > call _vputs
> > key_wait
> > xor a
> > call GET_KEY
> > cp K_PLUS
> > jr z,inc_contrast
> > cp K_MINUS
> > jr z,dec_contrast
> > cp K_EXIT
> > ret z
> > jr ProgStart
> >
> > inc_contrast:
> > ld a,($c008)
> > cp $1f
> > jp p,ProgStart
> > inc a
> > out (2),a
> > ld ($c008),a
> > jr ProgStart
> >
> > dec_contrast:
> > ld a,($c008)
> > cp 0
> > jp z,ProgStart
> > dec a
> > out (2),a
> > ld ($c008),a
> > jr ProgStart
> >
> > msg:
> > .db "The contrast is:",0
> >
> > .end
> >
> > ______________________________________________________
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>
>
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