The introduction to this activity said, "Even the most complicated software or cell phone app is made out of very simple steps that happen one at a time." That is not quite true. Each central processing unit core (CPU core) can process one instruction at a time. A quad-core computer processes four instructions at once. But any computer can run more programs "at once" than the number of processor cores it has. How do you think a dual-core computer, for instance, can make it look and feel like it is running ten or more programs at once?