* Unified hardware APIs:

[`audioio`](https://circuitpython.readthedocs.io/en/latest/shared-bindings/audioio/__init__.html),[`analogio`](https://circuitpython.readthedocs.io/en/latest/shared-bindings/analogio/__init__.html),[`busio`](https://circuitpython.readthedocs.io/en/latest/shared-bindings/busio/__init__.html),[`digitalio`](https://circuitpython.readthedocs.io/en/latest/shared-bindings/digitalio/__init__.html),[`pulseio`](https://circuitpython.readthedocs.io/en/latest/shared-bindings/pulseio/__init__.html),[`touchio`](https://circuitpython.readthedocs.io/en/latest/shared-bindings/touchio/__init__.html),[`microcontroller`](https://circuitpython.readthedocs.io/en/latest/shared-bindings/microcontroller/__init__.html),[`board`](https://circuitpython.readthedocs.io/en/latest/shared-bindings/board/__init__.html),[`bitbangio`](https://circuitpython.readthedocs.io/en/latest/shared-bindings/bitbangio/__init__.html) (Only available on atmel-samd21 and ESP8266 currently.)

* Tracks MicroPython's releases (not master).

* No module aliasing. (`uos` and`utime` are not available as`os` and`time` respectively.)

* Modules with a CPython counterpart, such as`time`, are strict[subsets](https://circuitpython.readthedocs.io/en/latest/shared-bindings/time/__init__.html) of their[CPython version](https://docs.python.org/3.4/library/time.html?highlight=time#module-time). Therefore, code from CircuitPython is runnable on CPython but not necessarily the reverse.

* No module aliasing. (`uos` and`utime` are not available as`os` and`time` respectively.) Instead`os`,`time`, and`random` are CPython compatible.

* New`storage` module which manages file system mounts. (Functionality from`uos` in MicroPython.)

* Modules with a CPython counterpart, such as`time`,`os` and`random`, are strict[subsets](https://circuitpython.readthedocs.io/en/latest/shared-bindings/time/__init__.html) of their[CPython version](https://docs.python.org/3.4/library/time.html?highlight=time#module-time). Therefore, code from CircuitPython is runnable on CPython but not necessarily the reverse.

* tick count is available as[`time.monotonic()`](https://circuitpython.readthedocs.io/en/latest/shared-bindings/time/__init__.html#time.monotonic)

*`os` only available as`uos`

* atmel-samd21 features

* RGB status LED

* Auto-reload after file write over mass storage. (Disable with`samd.disable_autoreload()`)