A Historical Perspective on Computer Arithmetic

My first experiences with decimal computer arithmetic in college (1963) influenced my subsequent career decisions and projects as described herein. Many popular early computers focused on commercial applications for which decimal arithmetic was appropriate. These digit-serial implementations did not minimize hardware cost, but provided the precision needed by the application. Decimal arithmetic as taught in elementary school is a fine starting point for describing computer operation, but for non-engineers the hardware realization of an adder is mysterious. Routing circuits, while not always practical, illustrate how two-bits can be added by using switches, relays, or MOSFET's.