<> Yes. The 8259 PIC (interrupt controller) is fully programmable for edge <> and level. It's possibel to go from edge to level on a common PC but you < < <Unfortunately the interrupt inputs on the 8259 are always active high <(specified clearly in the data sheet), so you still need inverters on all <the inputs for active-low lines. Yes and they would be needed as putting raw unbuffered mos inputs on a bus is bad form. <all, the reason for having a PC is compatibility. There are plenty of <nicer machines to hack about with (which is where we started). yes, multibus and other implmentations were better. Even S100 got that part right! Allison