Lpc2000

> What is neeeded (hardware & software) to debug in
> FLASH?

Which compiler?  I'll presume IAR as that's what the thread started was
enquiring about:

General Options, Debugger, Download tab:
If ....(default) is not in pane, select edit, new, ok, ok.

This will Flash your part upon entering debug.

Keep in mind the core only supports two hardware breakpoints.  Depending on
your debug settings one may be used by Clib stdio.
 
Joel