[xen2xen1]

And didn't the Apollo Guidance Computer do some of it in analog?

[jccooper]

It had manually encoded ROM in the form of "core rope memory", which is pretty wacky, but it was a digital computer. In fact, it was the first IC computer.

You can learn way too much about it and even operate (a simulation of) one here: http://www.ibiblio.org/apollo/