Hi I’m suspicious about macro "portDISABLE_INTERRUPTS()"  (in ARM7_LPC2129_Keil demo (ARM version)) don’t disable interrupts. I added infinite loop while(1); on line 168 in port.c in function "xPortStartScheduler(void)" just after "prvSetupTimerInterrupt();" and set a breakpoint in portISR.c line 138 in function     "void vPreemptiveTick(void) __task" on         portSAVE_CONTEXT();. When I run the program in Keil’s debugger (I’m not stepping, I just press Run), debugger reaches the breakpoint in ISR. I suppossed that interrupts should be disabled at this time, right? Is it OK? Demo works fine, at least it’s blinking with leds. Have a nice week-end, Mirek

see https://sourceforge.net/forum/message.php?msg_id=3769459