1. COMP 1321 Digital Infrastructure
Richard Henson
University of Worcester
September 2018

2. Session 1(b): Digital Electronics
“Digital” requires two states (eg on/off)
Electrical Relays achieved that… hence Colossus
Electronic Valves achieved that quicker than relays… hence ENIAC
Both very large and cumbersome

3. US domination (and why…)
Late 1930s: Shannon dug up Boole’s work
found a good fit between “true/false”, electronic “on/off” valves, and binary numbers “0/1”
used Boolean Logic to create circuits wit predictable outcomes
very cumbersome and used a lot of energy
1940s Europe devastated by war…
UK efforts… Bletchley Park
1949: ENIAC First commercial computer
still used valves
very large and power hungry

4. The Transistor
Invented in 1947 (John Bardeen, Walter Brattain & William Shockley)
like a valve but low voltage, low energy
made Shannon’s vision based on Boole’s maths a reality
By 1960s: First minicomputer, the DEC PDP-1 (Program, Data, Processor)

5. UK computing in the 50s & 60s The first “electronic brain”
The first electronic office:
The first electronic lottery:

6. Programming
“A computer will do what you tell it to do, but that may be very different from what you had in mind.”
Joseph Weizenbaum

7. US domination of software & hardware development…
1967: Relational database
1969: Internet begins with 4 mainframes
1971: Floppy disks
1972: Intel, microprocessor
1975: Apple, first microcomputer
1976: Wang, first VDU

8. The First “Infrastructure”
Mainframes had no infrastructure
Separate area of their own…
Paper in… paper out!
VDU (1976 on…) allowed interaction with mainframe
multiuser systems
screens on people’s desks
communication protocols and cabling

9. Continued US Dmination…
1976: Microsoft, computer language (BASIC) on a chip
1981: IBM PC teamed up with Microsoft
first Desktop Operating system, MS-DOS, used in Business
Standalone, so no infrastructure…

10. Growth of Infrastructure…
Suddenly, a requirement for computers to communicate with other computers…
Hardware & protocols further refined
networks grew rapidly
mainframe-mainframe
PC-PC
even mainframe to PC!
PC emulated a terminal

11. Complexity of Infrastructure
From one monster computer in one place (1960s, early 70s)…
to PCs standalone and linked together (1980s)
client-end usable by non-specialists
then PCs linked direct to mainframes!

12. Networking: Integration of Telephone & Digital Infrastructures
Computing: OSI model (1978)
digital & encryptable
International Standard in 1984
fast networks (10 Mb)
Telecoms… French domination
stubbornly analogue…
digital data had to be converted before/after transmission
slow 9 K, then 14.4K (wow!)

13. Integration of Telephone & Digital Infrastructures
Very slow evolution…
Speeded up thanks to the World Wide Web
Gradual evolution from analogue to digital telecoms (1990s/2000s)
ADSL and fast broadband possible (not rural areas…)

14. European Comeback? 1988 onward: mobile phone 1992: World Wide Web
ARM CPU chip (Acorn)
low power… used in many devices
1992: World Wide Web
EU research facility, CERN, under the Swiss Alps (Sir Tim Berners-Lee)
Late 1990s: Linux & Nokia

15. Still plenty of US domination…
i-player, i-phone, i-pad
Smart phone
Mobile apps
Tablets & e-books
Cloud computing
What next?… IoT, wetware?

16. What is Analogue? The “real” world
Everything before Boole’s digital logic started to be used by computers…
including programs that were written solely to depict the real world
Data represents quantities exactly
e.g. the size of an electric voltage, the frequency of a signal, etc.

17. Analogue and Digital Like computers…
most human inventions started out as analogue
Digital World ~ post-war human invention
based on George Boole’s maths… 100 years earlier
Discussion:
analogue or digital… which is best? Why?

18. Why Digital? Fits Computer Data… based on binary 0 and 1
two electrical states e.g. “on/off”, high/low voltage
worked for valves (ENIAC)
and transistors (DEC PDP)
became known as digital
Analogue remained for historical reasons… like degrees Fahrenheit?

19. Analogue to Digital Computers just don’t do analogue!
Devices had to be invented to convent analogue data to digital
input devices
always an approximation (can be a very close approximation…)

20. Digital but not whole? Any quantity can become digital!
(not just about whole numbers)
based on approximation…
Electrical on/off “state” represents data as (1s/0s)
presence/absence of an electric voltage
low voltage or higher voltage volts = off, 3-5 volts = on
binary (off = 0, on = 1)

21. Digital multimeter
Ref:

22. Analogue multimeter
Ref:

23. Summary of Developments
Digital only possible thanks to George Boole (1850s, UK)
hardware began with Lord Babbage, but mechanical (1850s UK)
programming started with Lord Byron’s daughter, Ada Lovelace (1850s UK)
programmable analogue machines popular…
Electronics used Boole’s maths to predict output
Digital Computers created (Colossus/ENIAC) programmed in binary… (0/1)
world gradually became digital…