Manual de Fritz 15 2015 | Page 252

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This has to do with the distribution of the processor time. The communication between
the user interface and the chess engine is carried out by a separate program, the
Engine Interface. The Engine Interface runs with low priority to give the chess engine
the maximum amout of ressources. Some UCI engines have problems with the default
setting because they use too many ressources and the Engine Interface cannot
receive the evaluation results and similar data. The setting "Lower priority" solves
display problems that arise when certain UCI engines are used.
Even when the lower priority is set a UCI engine receives all the processor speed it
needs and brings its best performance. This setting does not adversely affect the
performance of a UCI engine! This is easy to test by analysing the same position with
both settings. There is no change in the engine’s speed, it only makes the usage
smoother.
So why can the priority be lowered for the UCI engines and not for Fritz (and the
other engines sold by Chessbase)? The native Chessbase engines are linked as DLL’s
to the user interface, which means that unlike the UCI engines they are not external
processes. No external protocol is necessary, and no priority must be set.
See also Engine Interface ....

3.8.7

Hash tables
Hash tables are memory areas in which the program can store positions and
evaluations while it is calculating the moves of a game. If the program encounters the
same position again, it can simply take the evaluation from the hash tables, rather
than analysing the position all over again.

Hash tables increase the playing strength of the program considerably. This is
especially true of tactically strong engines like Fritz, Houdini or Kommodo. Some run at
well over 500,000 positions per second, and will fill the hash tables very quickly. After
that, the search slows down. This is not the case in a slower, positionally oriented
program, which processes less positions per second, and takes much longer to fill the
hash tables.

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