A new in-browser compiler
The compilation from the script to the ARM machine code is now done entirely in the browser thanks to the ARM thumb assembler written by Michał Moskal (read the in depth story about building the compiler).
The new compiler is used by the Block Editor, Touch Develop and Code Kingdoms to create the .hex file on the fly without having to rely on an cloud-based C++ compiler.
The BBC micro:bit compilation process (see page 10 in the Quick Start book) has been updated below to reflect the new compiler architecture.
As a result of running the entire compilation process in the browser, the new compiler works completely offline.
Save and load .hex files to see source code
Users are now able to import and export scripts as files. For example, they can simply email it or submit them in their classroom portal.
Compiled .hex files can also be imported back into the web site. This make it easy for a teacher to review the source of a script by simply drag and dropping the file into the editor.
This superb tool Automatic uploads .hex which are complied directly to a micro:bit which is connected via USB. Simply Download the microbit updater and install it to your PC.