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Technical Data

Here is an overview on the software, the hardware, and also the relevant authors who contributed to this project.


  • Author of the ARM-port: Rasmus Althoff.
  • Base program: NG-Play v9.86 (with extensive improvements and bugfixes).
  • Author of the base program NG-Play v9.86: George Georgopoulos.
  • Author of the endgame bitbase for king and pawn vs. king: Marcel van Kervinck.
  • Opening book: 22,900 different plies in 12,900 unique positions. Transpositions are recognised.
  • Hash tables: 100 kB.
  • Pondering: none.
  • Maximum search depth: 20 plies full search plus 8 plies quiescence.
  • Maximum game length: 250 moves.
  • Free ROM: The firmware image is 384 kB, out of which 269 kB are used. 109 kB are for the opening book data and 32 kB for the endgame bitbase.
  • Free RAM: 18.5 kB.
  • Strength: around 2100 ELO.
  • Operating system: none / bare metal.
  • Other platforms (via UCI): Windows, Linux, Android and Raspberry Pi.
  • Programming languages: mostly C (the best portable macro assembler ever!) and some assembly.
  • Compiler: GCC 7.3 Q2/2018 ARM none-eabi.
  • Licence: GNU General Public License, Version 3 or later.


  • CPU: ARM Cortex M4 (STM32F405RG in Olimex STM32-H405).
  • Speed: 168 MHz (100 %) while computing, 8 MHz while waiting for user input.
  • Clocking: the CPU speed during computing can be configured from 10 % to 140 %.
  • ROM: 1 MB.
  • RAM: 192 kB + 4 kB backup-RAM.
  • Display: text display with 4x20 characters, plus a red LED, a green LED and a buzzer.
  • Display backlight: controlled by software.
  • Input: 4×4 matrix keypad plus one switch for manual backlight activation.
  • Power input: 4×AA rechargeable NiMH batteries or via 5 V DC wall power adapter. Non-rechargeable batteries are also suitable, though not economic.
  • Battery running time: 37 hours at 168 MHz.
  • Current consumption at 5 V: 18 mA at 8 MHz (user’s turn), 81 mA at 168 MHz. Each plus 28 mA with active display backlight.