The Sim.One comes with a set of Free Software.
In this page we will analyze all its main components, that are:
the U-Boot Bootloader, the Linux Kernel, the Debian Operating System.

The U-Boot Universal Bootloader

U-Boot, is a Free Software that has the duty to inizialize the machine and prepare it for the Kernel booting.

It provides the following features:

• Initializing the hardware, especially the CPU and memory controller.
  
• Providing boot parameters for the Linux Kernel.
  
• Starting the Linux Kernel

And additionally it can:

• Reading and writing arbitrary memory locations.
  
• Uploading new binary images to the board's RAM via a serial line or Ethernet
  
• Copying binary images from RAM to FLASH memory

There is also a Stock EP9307 tiny bootloader in the CPU ROM, for full instructions in how to use the two bootloaders, you can visit the Bootloaders wiki page

The Linux Kernel

The Linux Kernel is the most popular Free Software Kernel for UNIX-Like operating systems, currently ported to thousand devices with different architectures.

Linux is the part that makes all other programs run:

• implements multitasking
• manages hardware devices
• enables applications to do their things
  
• all the programs that the user (or system administrator) actually interacts with are run on top of the kernel

The Linux Kernel officially support the Sim.One since version 2.6.36 and you can build an optimized Debian Armel Kernel following this wiki.

Debian, the Universal Operating System

To use the Linux Kernel, you have to choose a Linux distribution.
For several reasons, we have chosen to support one of the most popular and flexible, with thousand ready and easy to install software packages.

The Debian Operating System:

• is a Free operating system
• is the set of basic programs and utilities that make your computer run
• it uses the Linux Kernel (the core of an operating system), but most of the basic OS tools come from the GNU project; hence the name of the GNU/Linux.
• Debian GNU/Linux provides more than a pure OS: it comes with over 17000 packages , precompiled software bundled up in a nice format for easy installation on your machine.

You can use this guide to make a Debian root filesystem for the Sim.One using debootstrap and eventually add X Server graphics to it following this wiki .