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page.title=Android Core Technologies
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    <h2>In this document</h2>
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<p>Welcome to the Android core technologies section of the site. Here you
can find information on common features useful to people and organizations who
are looking to modify, contribute to, or port the Android software. This is
"under the hood" information intended for engineers.</p>

<h2 id="accessory-protocol-information">Accessories</h2>
<p>Android devices can connect to hardware accessories, such as audio docks,
keyboards and custom hardware, through USB or Bluetooth. This section
describes the Android Open Accessory protocol (AOAP) for accessory hardware
builders.</p>
<p><a href="{@docRoot}accessories/index.html">&raquo; Accessory Protocol
Information</a></p>

<h2 id="art-technical-information">ART</h2>
<p>The Android runtime (ART) is the heart of Android. It's a fast, ahead-of-time
compiled runtime with modern garbage collection designed to scale.
Android applications are compiled to Dalvik bytecode and run with ART. This
section includes detailed information such as the Dalvik Executable format
specification, and design information on the runtime itself.</p>
<p><a href="{@docRoot}devices/tech/dalvik/index.html">&raquo; ART and Dalvik
Information</a></p>

<h2 id="data-usage-technical-information">Data Usage</h2>
<p>Android's data usage features allow users to understand and control how
their device uses network data. This section is designed for systems
integrators and mobile operators to help explain technical details they
should be aware of when porting Android to specific devices.</p>
<p><a href="{@docRoot}devices/tech/datausage/index.html">&raquo; Data Usage
Information</a></p>

<h2 id="debugging">Debugging and Tuning</h2>
<p>Android is a large and complex system. This section includes tips and tricks
for debugging at the platform level.</p>
<p><a href="{@docRoot}devices/tech/debug/index.html">&raquo; Debugging
Information</a></p>

<h2 id="HAL-technical-information">HAL File Reference</h2>
<p>Android's Hardware Abstraction Layer (HAL) provides the interface between
software APIs and hardware drivers. This section contains the commented code
files of the HAL.</p>
<p><a href="{@docRoot}devices/halref/files.html">&raquo; HAL Reference</a></p>

<h2 id="kernel-technical-information">Kernel</h2>
<p>The kernel configuration settings in this section are meant to be used as
a base for an Android kernel configuration. All devices should have the
options in android-base configuration enabled.</p>
<p><a href="{@docRoot}devices/tech/kernel.html">&raquo; Kernel Information</a>
</p>

<h2 id="lowram-technical-information">Low RAM</h2>
<p>Android supports devices with limited memory through various optimizations
such as improved memory management, reduced system memory, and several
build-time and kernel configuration settings.</p>
<p><a href="{@docRoot}devices/tech/low-ram.html">&raquo; Low RAM Information</a>
</p>

<h2 id="ota-technical-information">OTA Updates</h2>
<p>Android devices in the field can receive and install over-the-air (OTA)
updates to the system and application software. This section describes the
structure of update packages and the tools to build them. It is intended for
developers building OTA updates for new and released Android devices.</p>
<p><a href="{@docRoot}devices/tech/ota/index.html">&raquo; OTA Information</a>
</p>

<h2 id="power-technical-information">Power</h2>
<p>Battery usage statistics are tracked by the framework. This involves
keeping track of time spent by different device components in different states.
</p>
<p><a href="{@docRoot}devices/tech/power.html">&raquo; Power Information</a>
</p>

<h2 id="security-technical-information">Security</h2>
<p>Android security comes with a variety of measures, including an application
sandbox, SELinux, dm-verity, encryption, and more.</p>
<p><a href="{@docRoot}devices/tech/security/index.html">&raquo; Security
Information</a></p>

<h2 id="tradefed-test-infrastructure">Trade Federation Testing Infrastructure
</h2>
<p>Trade Federation is a continuous test framework for running tests on
Android devices. Trade Federation's modularity makes it straightforward to
slot into environments with existing build, test, and reporting
infrastructures.</p>
<p><a href="{@docRoot}devices/tech/test_infra/tradefed/index.html">
&raquo; Trade Federation Testing Infrastructure Overview</a></p>