[A83] Re: im 2

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[A83] Re: im 2


> Van: Tijl Coosemans <tijl.coosemans@mail.be>
> 
> > From: David Phillips <david@acz.org>
> 
> > > I know, but I brought up the issue again, because my routine
> > > really needs to be as fast as possible. Every tstate counts.
> > > So I thought, by splitting it up into several routines, which are
> > > randomly called, each routine could be faster than when I had
> > > to put them together and built in a counter.
> 
> > What are you doing that is so time critical?
> 
> Can't really tell yet :)

I won't tell either (I do know what he is trying to do) :-)

Just trust me he, what he want's to do can be really helpfull (for nearly
all of you).

> > Your logic doesn't make any sense.  Having less control over your
> > program doesn't make it faster.

Oh yes, it can...

> Now I actually have three routines. Each interrupt another one is
> called and the order in which that happens doesn't really matter. I do
> that by implementing a counter which counts from 1 to 3. If I could
> make an interrupt vector table with 3 pointers instead of one, I wouldn't
> have to implement that counter, which could safe me a few clock cycles.
> Not much, but as I said, every tstate counts.

> > > As far as I know now, the lower bit seems to be more 1 than 0. Also,
> > > when I use a _getcsc/halt loop in the main program, the lowest bit
> > > seems to be always 1, resulting in aligned addresses. Don't ask me
> > > why that is.
> 
> > How are you reading the value?  I don't have any proof, but reading the
> > register might always return the same value, or a different one than
> > the calc uses when an interrupt occurs.  The only way to really test it
> > is to put in different interrupt routines at different addresses, and
see
> > what happens.  Or put garbage in half the bytes, and see if it crashes.
> 
> I used two routines. One at 8587h and one at 8785h. Then I made a
> vector table at 8600h-8700h. One time I let it start with 85h (, 87h,
85h,
>  87h, ...) and the other time with 87h(,85h,...) and saw what happent.
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