hi I work by LPC2138/01, and i config I/O ports as fast I/O(SCS=0x3). i change I/O pin in simulation exactly, also I/O pins change whitout any problem in run mode. but i cannot change I/O pin in debugging mode, even when i click a bit on PINxDIR register manually, it unchecked after a short time. I use Keil V4.6.00. How can I solve my problem by fast I/O pin in debug mode???