Hello, here's a question about the interrupt handling of a Siemens 80C165: I use the external interrupt 5, which works like it should. Sometimes, I want to disable that interrupt, so that the controller doesn't recognize an incoming interrupt. Therefore, I have a function to enable/disable that interrupt: void ExtInt5 (bit en) { if (en) { EXI5ESH = 1; EXI5ESL = 0; CC13IE = 1; CC13IC |= 0x04; } else { CC13IE = 0; } } Calling that function with en=1 enables the interrupt input (CC13IE = 1) and I get the immediate response if there's an interrupt condition. If I disable the interrupt (CC13IE = 0), the system doesn't respond on an interrupt condition anymore... like it should be, but: As soon as I enable the interrupt again, the controller jumps into the Interrupt service routine, if there was an interrupt condition while it was disabled. Why does it even recognize the interrupt if CC13IE = 0? It seems that this register only prevents the controller from jumping to the interrupt service routine, but doesn't disable the interrupt at all. And how would I really disable the interrupt? Thanks for any help! Holger