HCI-631: Software Architectures for User Interface Scott Hudson Office: NSH 3523 Office Hours: Tues 3:00-4:00 (and by appointment)

2 What is this class about? n Organizing principles of UI software n Practice in UI implementation n (About HCI-630…)

3 Why is this interesting? n Computers are exploding into society – Pervasive computing power – Small, cheap, powerful

4 World’s smallest web-server (runs Linux)

5 That only lasted 3 months…

6

7 Parts cost is around $1 n If you can add $3-$5 to the cost of something, you can add a processor – if there is something of value to be gained (doesn’t have to be much)

8 Parts cost is around $1 n ~80x faster than the computer that “landed men on the moon” <50Khz (0.05Mhz)vs. 4Mhz n And ~2x memory ~2K RAM, ~64K ROM vs. 41b RAM, 259K EEPROM

9 We haven’t seen anything yet n Pop quiz: what is this  Good Stuff Time 

10 Moore’s Law  Good Stuff Time  You are here

11 Moore’s law n At given price point, CPU speed doubles every 18 months – Low end (<$1) chip will have today’s high-end performance in ~10 years n Corollary: at a given performance point price drops fast

12 Hard to really understand exponential growth n There has been huge performance gains since (say) 1965

13 Hard to really understand exponential growth n There has been huge performance gains since (say) 1965 n EVERY SINGLE BIT of those speed gains will happen again in 18 months!!

14 Thought experiment From Douglas Engelbart (invented mouse & hypertext) n Suppose you and everything you could see suddenly got exactly 10 times bigger. n Could you tell the difference?

15 Thought experiment From Douglas Engelbart (invented mouse & hypertext) n Mass scales by volume, but strength of your chair scales by cross-sectional area – Chair collapses under 10x weight ratio – Not so important because many of your bones will break for the same reason – Not really an issue because oxygen consumption scales by volume, but lungs’ ability to absorb it scales by area

16 Thought experiment From Douglas Engelbart (invented mouse & hypertext) n Moral of the story: Large (order of magnitude) changes can have a huge impact  Good Stuff Time  You are here

17 Thought experiment From Douglas Engelbart (invented mouse & hypertext) n Moral of the story: Large (order of magnitude) changes can have a huge impact n All hell is about to break loose! Cool!But only if its usable!

18 End result: big impact on the world n Large numbers use computers – Report: 50% of Americans now have internet access n No one in our society is not affected in some way by computers

19 Massive computational power available for next to nothing n No longer “Can you build it?” n Now: “Can they use it?” (“Will they use it” => “Can I sell it”) n This class is to teach fundamentals of building (usable) interactive systems

20 Syllabus n Me n Text n Projects n Grading (55% proj, 45% exams) – Midterm and comprehensive final

21 Syllabus n On-line materials: / (any second now…) n Schedule – Don’t take this TOO seriously

22