Winter 2016CISC101 - Prof. McLeod1 Today Take some of the “MAGIC” out of how computers work: How did the technology get to where it is today? –ENIAC movie (I hope!) –The Transistor –Integrated Circuit Fabrication Then, if we have time – how to add two integers in an integrated circuit (like a CPU!).

Winter 2016CISC101 - Prof. McLeod2 ENIAC, Cont. See the video (that did not play last time!) at:

Winter 2016CISC101 - Prof. McLeod3 Transistors, Cont. Individual: Integrated Circuits (started: 1958)

Winter 2016CISC101 - Prof. McLeod4 Integrated Circuits, Cont. Electron microscopy:

Winter 2016CISC101 - Prof. McLeod5 Moore’s “Law” “The number of transistors in a processor will double every 24 months.”

Winter 2016CISC101 - Prof. McLeod6 Moore’s “Law”, Cont. First documented by Intel co-founder Gordon E. Moore in 1965.

IC Fabrication Videos IC Fabrication IC Fabrication IC Fabrication (Watch the first one in class only.) Winter 2016CISC101 - Prof. McLeod7

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 2016CISC101 - Prof. McLeod8

Winter 2016CISC101 - Prof. McLeod9 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 2016CISC101 - Prof. McLeod10 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 2016CISC101 - Prof. McLeod11 Transistors - Cont. 1) No signal: 2) Add voltage to gate: 3) If drain is connected: 4) No signal on gate:

Winter 2016CISC101 - Prof. McLeod12 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 2016CISC101 - Prof. McLeod13 “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 2016CISC101 - Prof. McLeod14 “OR” Gate Either Input-1 or Input-2 can cause Output to be “On”. An “OR” gate in a logic diagram.

Winter 2016CISC101 - Prof. McLeod15 “NOT” Gate The “NOT” gate just reverses the Input:

Winter 2016CISC101 - Prof. McLeod16 “NOR” Gate Same as NOT(OR), like an OR gate followed by a NOT gate.

Winter 2016CISC101 - Prof. McLeod17 “NAND” Gate Same as NOT(AND), like an AND gate followed by a NOT gate.

Winter 2016CISC101 - Prof. McLeod18 “XOR” Gate X Y Z=X  Y XOR gate (These are NOT(AND) or “NAND” gates.) One way:

CISC101 - Prof. McLeod19 Summary: “Truth” or Logic Tables AND I1I1 I2I2 Output OR I1I1 I2I2 Output NOT I Output NAND I1I1 I2I2 Output NOR I1I1 I2I2 Output XOR I1I1 I2I2 Output

CISC101 - Prof. McLeod20 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 2016

CISC101 - Prof. McLeod21 Digital Circuits Generally, a digital circuit can be represented by: Remember that an input or output can only be either on (1) or off (0). The gates defined above can be used to design circuits that provide a desired logic. Winter 2016