1. CISC101 Reminders Course Web Site:
Winter 2019 CISC101
4/3/2019
CISC101 Reminders
Course Web Site:
Labs start next week. Meet your TA! Get help with:
Exercise 1.
Python installation issues.
Lecture material.
Assignment expectations….
Winter 2019
CISC101 - Prof. McLeod
Prof. Alan McLeod

2. Today
Continue some “tidbits” of the History of Computing: How did the technology get to where it is today?
von Neumann Architecture
The Transistor
Integrated Circuits
Logic Gates (if we have time)
Winter 2019
CISC101 - Prof. McLeod

3. Last Time – The ENIAC, Cont.
Six women (inducted into the Women in Technology International Hall of Fame) took several weeks to manually enter a single program into the machine:
Kay McNulty, Betty Jennings, Betty Snyder, Marlyn Wescoff, Fran Bilas and Ruth Lichterman
Winter 2018
CISC101 - Prof. McLeod

4. Operating the “Differential Analyzer” (an analog mechanical calculator) in the basement of the Moore School ( ):
Winter 2018
CISC101 - Prof. McLeod

5. ENIAC, Cont. In 1942, their annual salary was $1,620
The job title of all of the women was “Computer”!
Winter 2018
CISC101 - Prof. McLeod

6. von Neumann Architecture
Conceived in 1944/5
The structure we have been referring to is still used in modern computers:
Separate units for input and output.
Data is stored in a separate memory location.
The “ALU” carries out instructions on data items moved into the ALU.
The “Control Unit” acts as a stage manager.
Winter 2018
CISC101 - Prof. McLeod

7. “von Neumann Cycle” Fetch
The address of the next instruction is read from the instruction counter. The next instruction is read from this memory address to instruction register.
Decode
The instruction is translated to a format that is usable for the execution unit by the decoder.
Fetch operands
Depending to the actual instruction operands from a memory location have to be fetched to be accessible for the execution unit.
Execute
The arithmetical logical unit performs the operations and writes the results to registers or memory according to the instruction.
Update instruction counter
The instruction counter is incremented for the next cycle. Now the first step can start again.
Winter 2018
CISC101 - Prof. McLeod

8. Aside – The First Computer Bug
In 1947 Grace Murray Hopper was a technologist on a Mark II Aiken Relay Calculator at Harvard University. She logged the following:
Winter 2018
CISC101 - Prof. McLeod

9. Admiral Grace Murray Hopper
The word went out that she had “debugged” the machine.
Grace Murray Hopper became known as the “Mother of Cobol” and is one of the most important people in the history of computers.
Awarded (posthumously) the Presidential Medal of Freedom in 2016.
Winter 2018
CISC101 - Prof. McLeod

10. Admiral Grace Murray Hopper, Cont.
See:
She “owns” an interview on the David Letterman show…
Winter 2019
CISC101 - Prof. McLeod

11. After the ENIAC Only this one ENIAC was ever built.
It was followed by the “EDVAC” in 1950.
The first commercial computer was the UNIVAC I, which was delivered to the Bureau of the Census in the U.S. in 1951.
Walter Cronkite at right…
Winter 2018
CISC101 - Prof. McLeod

12. Before Transistors…
Winter 2018
CISC101 - Prof. McLeod

13. Vacuum Tubes, Cont.
A bias voltage on the grid allows current to flow between the emitter (cathode) and the collector (anode).
(Can also be used as amplifiers.)
Large, lots of heat generated, lots of energy required…
Winter 2018
CISC101 - Prof. McLeod

14. Transistors
First demonstrated in 1947, at Bell Labs by William Shockley:
Winter 2018
CISC101 - Prof. McLeod

15. Transistors, Cont. Individual: Integrated Circuits (started: 1958)
Winter 2018
CISC101 - Prof. McLeod

16. Integrated Circuits, Cont.
Electron microscopy:
Winter 2018
CISC101 - Prof. McLeod

17. Moore’s “Law”
“The number of transistors in a processor will double every 24 months.”
Winter 2018
CISC101 - Prof. McLeod

18. Moore’s “Law”, Cont.
First documented by Intel co-founder Gordon E. Moore in 1965.
Is there a limit to Moore’s Law?
Limited by atom size?
Limited by our ability to get the heat out?
Limited by manufacturing capability?
Are there alternatives to Si based transistors?
Winter 2018
CISC101 - Prof. McLeod

19. Integrated Circuit Fabrication
See video at:
(Lots of others…)
Winter 2018
CISC101 - Prof. McLeod

20. How to Make an IC Try this at home! (Just kidding...) Basic steps:
Create and refine huge single crystal of Silicon (Si).
Cut wafers.
Apply photo-resist layer.
Expose pattern on photo-resist using UV light.
Remove exposed photo-resist, etch out exposed Si.
Dope exposed Si using ion implantation.
Remove all photo resist.
Add insulating layer with holes.
Electroplate with copper.
Build circuit above transistors with more copper.
Test, slice and package up.
Winter 2018
CISC101 - Prof. McLeod

21. Digital Systems Logic - Transistors
Transistors can be used to provide digital logic.
They work just like the following circuit:
Each wire in a computer has a signal that is either on or off for the duration of a single clock tick (a very short time!).
Winter 2018
CISC101 - Prof. McLeod

22. Transistors (Shamelessly borrowed from the Intel web site:)
Of course, on a CPU, these are all made on a base of single crystal Silicon, and layers are added and etched using photo-resist technology.
Doping determines whether it is “n” or “p” type Si.
Winter 2018
CISC101 - Prof. McLeod

23. Transistors - Cont. 1) No signal: 2) Add voltage to gate:
3) If drain is connected:
4) No signal on gate:
Winter 2018
CISC101 - Prof. McLeod

24. Transistors - Cont.
Source, Gate and Drain are also called “Collector”, “Base” and “Emitter”:
A 5V signal applied to the gate or “base” is enough to cause current to flow. Zero volts turns the signal off.
Combinations of transistors can be used to perform boolean logical functions, called “gates”:
Winter 2018
CISC101 - Prof. McLeod

25. “AND” Gate Two transistors forming an “AND” gate:
Both Input-1 and Input-2 have to be “1” (ie. 5 volts) for the Output to be “on”.
How an “AND” gate is drawn in a logic diagram:
Logic or “Truth” table:
Winter 2018
CISC101 - Prof. McLeod

26. “OR” Gate Either Input-1 or Input-2 can cause Output to be “On”.
An “OR” gate in a logic diagram.
Winter 2018
CISC101 - Prof. McLeod

27. “NOT” Gate The “NOT” gate just reverses the Input: Winter 2018
CISC101 - Prof. McLeod

28. “NOR” Gate Same as NOT(OR), like an OR gate followed by a NOT gate.
Winter 2018
CISC101 - Prof. McLeod

29. “NAND” Gate Same as NOT(AND), like an AND gate followed by a NOT gate.
Winter 2018
CISC101 - Prof. McLeod

30. “XOR” Gate One way: XOR gate X Z=XY Y
(These are NOT(AND) or “NAND” gates.)
Winter 2018
CISC101 - Prof. McLeod

31. Summary: “Truth” or Logic Tables
AND OR I1 I2
Output I1 I2
Output
NOT I
Output 1 1 1 1 1 1 1 1 1 1 1 1 1 1
NAND
NOR
XOR I1 I2
Output I1 I2
Output I1 I2
Output 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
CISC101 - Prof. McLeod

32. Summary, Cont.
Gates: You can use transistors to build a circuit, or “gate”, that provides the logic for each of these operators.
Notation:
ab (you will also see just “ab”) means “a AND b”
a+b means “ a OR b”
a means NOT(a)
ab means “a XOR b”
Winter 2018
CISC101 - Prof. McLeod