ARMbasic is an incremental compiler, meaning that you can enter a portion of a program, run it, check some variable values, enter some more code and run it again...   This operates much like an interpreter, so that debugging of code can be done very quickly.  

There are a number of operations that aid during the debug phase of programming an ARMexpress.  These allow you to read and write memory locations which also includes the registers of the many ARM peripherals.

Debugging Functions
    !      -  write to memory
    @    -  read memory