4 Paradigms

How can a system be developed to have better usability?
How can the usability be demonstrated or measured?

Time sharing
	Computer is valuable and expensive
	How can we get better use?
Video display units
	1962 sketchpad
Programming toolkits
	Use computer to help humans learn
	Word processing, mouse
Personal computing
	LOGO (Seymour Papert)
		Small children could program
	PC Xerox Heath Kit
	Commodore
		PET VIC20
		C64
	IBM PC
	Apple I, II, Lisa, MacIntosh
WIMP windows
Metaphor
	Initial start
	Never perfect
	Cultural bias
Direct manipulation
	Rapid feedback
	Evaluate every action
	Visibility
	Incremental action
		Feedback
		Reversibility
		Syntax
		Replace complex commands with direct manipulation
		(Macintosh)1984
Language
	User does not need to understand ‘insides’
	Actually, easier to do more complicated tasks
	(macros, subroutines)
Programming by example

Hypertext
Multi-modality
	Keyboard
	Mouse
	Display
	Gestures
Computer supported cooperative work
	Email
	telnet
	groupware
world wide web
	(subset of Internet 1969)
	TCP/IP
	IP addresses and domain names
	HTML hypertext markup language
		Allows visual web pages
		1991 first text browser
		1993 mosaic graphic browsers
Agent based interfaces
	Software to do tasks on our behalf
Ubiquitous computing
	Your toaster
	Your car
	Your phone
	Etc
Sensor based
	Hold your hands under faucet
	Appropriate intelligence
	Be right often
	Do not cause big problems if wrong