Sketchpad was the first graphical computer program, created by Ivan Sutherland for his PhD thesis. It introduced concepts foundational to computer-aided design (CAD), graphical user interfaces, and object-oriented programming.
Revolutionary Interaction
Sketchpad allowed users to draw directly on a display screen using a light pen. This was revolutionary—most computers at the time used punch cards and printed output.
Key Innovations
Sketchpad introduced concepts that became fundamental:
- Direct manipulation: Draw and modify on screen
- Constraint satisfaction: Lines stay connected when moved
- Master drawings: Reusable components (like objects/classes)
- Zooming: Scale drawings up and down
- Copy and instance: Duplicate with maintained relationships
Object-Oriented Concepts
Sketchpad’s “master drawings” anticipated object-oriented programming:
- Masters defined structure and behavior
- Instances inherited properties from masters
- Changes to masters propagated to instances
Impact
Sketchpad influenced:
- CAD (Computer-Aided Design) systems
- Graphical user interfaces
- Object-oriented programming
- Virtual reality research
Sutherland received the Turing Award in 1988 for this pioneering work.