Hi, I need some more information regarding the interrupts priorities in 8051. If a low priority interrupt occurs while a high/low priority interrupt service routine is running, Is the low priority interrupt that occured is lost and won't be handled after the running ISR is completed? While EA=0(all interrupts disabled)and an interrupt occures,is it lost?which means does the uPSD remebers the interrupt activation and jumps to its ISR after EA is set? Is it important if the interrupt that occurs while EA=0 is a high or low priority interrupt? If all interrupts are with the same priority ,does in this case servicing the interrupts is based only on the priority level chart?which means will interrupt ext0 be serviced before timer0 for example(in case both arrive at the same time)? Thanks .