MCBSTM32F400
The evaluation-board MCBSTM32F400 I started to work with in 2014
using uVision 3 and this board I still have in use.
The board has the ARM-Cortex-M4-CPU ( 32-bit ) running at 168 MHz
and has 2 MB external SRAM.
This is the first board running with the bitmap-engine Crafty-X.
I clearly remember that it was for longer time unknown if this engine will run
at all on this board.
Reason was that a bitmap-engine requires much more RAM compared to classical
chess-programs not using bitmaps.
Classical programs work already with 4 KB RAM ( or even less ).
In the end it has turned out that the 2 MB external SRAM were enough to get the system running.
The complete engine-data requires at startup around 1.2 MB,
the rest is available for hashtables.
The move-generator of a bitmap-engine is much more complicated compared with a classical mailbox-move-generator, many data will be created at startup and than keept available in RAM as lookup-tables.
This board still requires an external programmer ( as the MCBSTM32E do ),
available as plug-in, to be able to flash the flash-ROM with data.
Newer boards have already available such devices onboard.
Up to now this is the only engine including an working opening-library.
The library may be designed as desired and the final .bin-file is available
on SD-card.
For later boards the opening-library is still missing, mainly because the library
has not directly to do with the engine and the stuff connected to it.
The engine plays pretty well and uses many modern search-strategies known today,
like null-move, late-move-reduction ( LMR ), late-move-pruning ( LMP ), futility and
search-extensions.
Hashing ( recognizing move-transpositions ) is working as well
and results in deep searches in some endgames, not possible without hashing.
Although there remains only around 500 KB RAM for the hashtables,
this is enough for around 20.000 hash-entrys resulting in strong play.
Depth 14 is usualy reached in tournament-mode, I would estimate the playing-strength here at 2350 ELO.
Max depth is 65 halfmoves.
I have in use this board frequently as opponent for other boards and for tuning-purposes.