> when you say "external" do you mean a hardware interrupt (such as an > IRQ for PC's)? if so, i do not think there is a way to cause one. > you can do software interrupts if you use one of the new shells > (usgard or rigel). Yes. Oh, I'm sorry to hear that. Does the calc have a timer that can cause interrupts? Don't most z-80 cpus have timers? Thanks!! Ming