Computing History Displays: Third Floor - Main Frame sculpture

This sculpture by Leigh Christensen was acquired for the Computer Science Department in 2010.

The sculpture was inspired by the logic circuits that are used in the design of computers. It represents a circuit for adding two 2-bit binary numbers to produce a 3-bit sum. It also shows how the circuit works, using ball-bearings to represent bits. Large ball-bearings represent 1, small ball-bearings are 0.

After the circuit has been initialized the numbers to be added are set-up on the top plank, for example 2 + 3:

If the ball bearings are released, after a great deal of activity, the sum will eventually appear at the bottom plank, in this case 5:

The logic of the circuit is entirely correct and is typical of the serial circuits used in the very first computers. There is a lot more detail on the sculpture, how it works and how to operate it, here.

Main Frame was the centre piece of an exhibition by Leigh Christensen at the Oedipus Rex Gallery in 1994. The exhibition comprised a number of pieces inspired by the computers and their history. We have two other works from the exhibition on display, the Difference Engine on floor 2 and Bessie and the Bug on floor 5.