Re: LZ: Screen Reversing...
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Re: LZ: Screen Reversing...
On Mon, 8 Oct 1996, Ben Shakal wrote:
> > > I want to add screen reversing to my etch a sketch thing... i have the code
> > > from another program but it is uncommented can someone send me a commented
> > > version of screen reversing! (pixel on to pixel off and vice versa)
> >
> > well.. (writing on-line, so prolly not 100% error-free)
> >
> > ; ------ clippityclippityclip ------------------
> >
> > [a bunch of code]
> > neg ; a=0-a, so all 1->0 and 0->1
>
> According to my Z80 programming book, this instruction will flip all
> the bits and then add one:
> in: 0101 1010
> out: 1010 0110
> What might work is the cpl instruction. Hope this helps!
Whoops... Sorry... Maybe I should've thought a bit... When it said 0-a, i
read $FF-a... my mistake...
-Pyrone
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