Historically, computers evolved from mechanical computers and eventually from vacuum tubes to transistors. However, conceptually computational systems as flexible as a personal computer can be built out of almost anything. For example, a computer can be made out of billiard balls (billiard ball computer); an often quoted example.[citation needed] More realistically, modern computers are made out of transistors made of photolithographed semiconductors.
Vacuum tubes in early computers were replaced by what?
transistors
Historically, computers evolved from mechanical computers and eventually from vacuum tubes to transistors.
Historically, computers evolved from mechanical computers and eventually from vacuum tubes to transistors.
Vacuum tubes in early computers were replaced by what?