What was the computer made of?

Answer 1

Several early digital computers were made of electromechanical devices similar to those used to build automatic dial telephone exchanges used at the time.

First generation digital computers were made of vacuum tubes.

Second generation digital computers were made of discrete transistors (most used germanium transistors but later some silicon transistors).

Third generation digital computers were made of (hybrid, SSI, MSI, LSI) silicon integrated circuits.

Fourth generation digital computers are made of microprocessors and other (VLSI, ULSI, etc.) silicon integrated circuits.