Hardware

Babbage's Difference Engine and other historic computers

Adding across columns

These small brass arms allow the machine to carry the calculation across the seven columns.

Photo credit: Jitze Couperus

About

Bill Detwiler is Managing Editor of TechRepublic and Tech Pro Research and the host of Cracking Open, CNET and TechRepublic's popular online show. Prior to joining TechRepublic in 2000, Bill was an IT manager, database administrator, and desktop supp...