A86: Re: Contrast
[Prev][Next][Index][Thread]
A86: Re: Contrast
Wow, we do asm programming here? (after 20 hours, I have ~65 messages NOT
related to asm programming)
To physically change the contrast, you must send the value to port 2:
ld a,2 ; set contrast really low
out (2),a ; physically set it
Now, you can't read from the port. So, the OS keeps track of it at location
$c008. So to get the current location, read it from $c008.
ld a,($c008) ; get contrast level
Then, modify it:
add a,2 ; increase 2 notches
Then write it back to $c008, and to physically set it, write it to the port:
ld ($c008),a ; save it, so the OS knows what it should be
out (2),a ; actually set it
>
> To check the contrast level you check the value at $C008, right? But if I
> remember correctly you can not write to that location... if that's true...
is
> there a way to change the contrast in a program. ie where do I write a
value
> to? I seem to remember someone saying something about this... I just
don't
> remember now. Thanks.
References: