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Re: RFC : SOME IDEAS FOR THE APPLE II FPGA'ers



John B. Matthews wrote:
In article <G6udnT6K3uy7S8TZRVn-iA@comcast.com>,
 "Michael J. Mahon" <mjmahon@aol.com> wrote:


John B. Matthews wrote:

In article <1herr66.1so9jr81ndbcbgN%bieling@terra.es>,
bieling@terra.es (Jorge Chamorro Bieling) wrote:



But I'd like to be able to know *exactly* how many cycles does a certain
piece of code take to execute. You never know for sure when it's being
cached. I would be better to count on fixed, known and fast memory
cycles, this is the true Apple II style... isn't it ?


I recently dusted off some EDASM documentation:

http://www.wright.edu/~john.matthews/a2/rel.html#tblb1

The directive "LST cyc" adds a cycle count to each line of the listing. I haven't checked it for accuracy (page crossing, etc), but it looks right.

In practice, I find it of limited usefulness because of conditional
branches and page crossings, etc.  You still need a pencil and
paper, but the cycle listing annotations can save a little time.


Too true. I used to use the feature to see if I was making progress. That way, I could waste time bumming code that wasn't critical:-)

I generally use it to get exact cycle counts for critical
loops and paths, but it seldom saves more than 25% of the
work.

-michael

Music synthesis for 8-bit Apple II's!
Home page:  http://members.aol.com/MJMahon/

"The wastebasket is our most important design
tool--and it is seriously underused."