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This file contains the instructions how to install the executable under
Android. Note that there is no GUI included because the engine is intended to
be used with chess GUIs like "Chess for Android" (see
https://play.google.com/store/apps/details?id=com.google.android.chess ) or
also "Droidfish" (see
https://play.google.com/store/apps/details?id=org.petero.droidfish ).

The CT800 engine supports the UCI protocol only.
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System requirements:
- 300-350 kB of internal storage, depending on the CPU architecture.
- During runtime, at least 2 MB of free RAM.
- Android version: 32 bit: 4.1 or higher (API level 16, Jelly Bean).
                   64 bit: 5.0 or higher (API level 21, Lollipop).
- CPU: for 32 bit ARM binary: ARMv7-A or higher.
       for 64 bit ARM binary: ARM64-v8A or higher.
       for 32 bit x86 binary: x86 or x86-64.
       for 64 bit x86 binary: x86-64.

There are four different binaries that you can choose from. They are not
bundled together into a single binary as not to waste space on your
phone, plus that you may want to test which version gives best results.

Note: if you are not sure which version to use:

      1) in 95% of the cases, the 64 bit version from the Android-ARM
         directory will be the best choice. Usually, Android devices have
         an ARM-64 CPU.

      2) if the device is very old, then it may instead need the 32 bit
         version from the Android-ARM directory.

      3) if your device has an Intel processor, x86 is most likely right, so
         it is the 32 bit version from the Android-x86 directory.

      4) devices using Intel and 64 bit are very rare, but even these should
         work with the 32 bit binary. The 64 bit binary could be a little
         faster.

      5) Intel devices can also use the ARM 32 bit binary, but that will slow
         down the engine to about 50% compared to using the x86 version.
         If you want to throttle the engine in order to reduce the playing
         strength, it is better to use the "CPU Speed" options of the engine.
         This way, the engine reduces its computing speed along with its
         energy consumption, and that will give you longer battery life.

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An example using the "Chess for Android" GUI from the Google play store:

- Install the "Chess for Android" GUI (access rights for SD card needed).
- Copy the CT800 engine executable to the SD card. Choose the version that
  matches your device (ARM / x86 and 32 bit / 64 bit), see above.
- In "Chess for Android", press the menu button or swipe up.
- Long-press anywhere to enter the extended menu.
- Go to "UCI and XBoard".
- Select "Install Engine from SD".
- Select the CT800 engine executable.
- The CT800 engine supports the UCI protocol only.

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For other GUIs:

- Follow the instructions of your chess GUI how to register the engine with
  your chess GUI.
- Choose the CT800 engine version that matches your device (ARM / x86 and
  32 bit / 64 bit).
- The CT800 engine supports the UCI protocol only. You should select "use
  engine book" because the opening book is tuned to the engine's style.

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Note: The opening book is contained in the executable, as well as the endgame
      bitbase for KPK, so there are no additional paths to configure. All of
      the engine options are available through the "engine options" section
      of the GUI.

Note: The engine uses 8 MB as default size for the hash tables. For better
      performance, 256 MB are recommended, which you can control through your
      GUI. (The system requirements state 2 MB minimum RAM because the engine
      will automatically fall back to 1 MB hash tables if it cannot get 8 MB.)

Note: The CT800 engine does not need special rights since it does not access
      your personal data, camera, microphone, GPS, network or whatever.

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