# Introduction to Electrical Engineering II Prof. Dr. Hasan H. Erkaya Eskişehir Osmangazi University 2008 Logic Systems and Gates.

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Introduction to Electrical Engineering II Prof. Dr. Hasan H. Erkaya Eskişehir Osmangazi University 2008 Logic Systems and Gates

Systems Analog System: a system in which variables are allowed to take any value within a range:

Analog Systems An electrical circuit:

Analog Systems Another electrical analog circuit:

Systems Digital System: a system in which variables are allowed to take only predetermined finite number of values

Digital Systems

Binary numbers are used to represent most digital systems. Binary digit = bit ( 0, 1) 8 bits side by side = 1 byte (e.g. 10011011)

Binary Systems A physical variable is used to represent binary values: e.g. a voltage or a current

Binary Systems Analog to Digital Converter

Binary Systems Digital to Analog Converter

DAC

Why bother with digital systems? Digital sistems can process information a lot easier than analog sistems Digital computer is much more skilful than the analog computer Is there an analog computer, too? (Yes! It can take derivative, integral and do other operations)

Boolean Algebra Basic Operations AND OR NOT Gates are used for these operations

AND gate A. B

OR gate A+B

NOT gate (inverter) A _

Combined Gates AND + NOT = NAND OR + NOT = NOR

Exclusive OR

Exclusive NOR

Logic Functions

Truth Table ABCF 0000 0011 010x 011x 100x 101x 1101 111x

Karnaugh Maps

K-maps

Building the Circuit Often NAND gates are used to implement the logic functions

7400 series ICs 7400: Quad 2-input NAND Gate 7401: Quad 2-input NAND Gate with Open Collector Outputs 7402: Quad 2-input NOR Gate 7403: Quad 2-input NAND Gate with Open Collector Outputs (different pinout than 7401) 7404: Hex Inverter 7405: Hex Inverter with Open Collector Outputs 7406: Hex Inverter Buffer/Driver with 30V Open Collector Outputs 7407: Hex Buffer/Driver with 30V Open Collector Outputs 7408: Quad 2-input AND Gate 7409: Quad 2-input AND Gate with Open Collector Outputs

7400 series ICs 7410: Triple 3-input NAND GateNAND Gate 7411: Triple 3-input AND GateAND Gate 7412: Triple 3-input NAND Gate with Open Collector OutputsNAND GateOpen Collector 7413: Dual Schmitt trigger 4-input NAND GateSchmitt triggerNAND Gate 7414: Hex Schmitt trigger InverterSchmitt triggerInverter 7415: Triple 3-input AND Gate with Open Collector OutputsAND GateOpen Collector 7416: Hex Inverter Buffer/Driver with 15V Open Collector OutputsInverterOpen Collector 7417: Hex Buffer/Driver with 15V Open Collector OutputsOpen Collector 7419: Hex Schmitt trigger InverterSchmitt triggerInverter 7420: Dual 4-input NAND GateNAND Gate 7421: Dual 4-input AND GateAND Gate 7422: Dual 4-Input NAND Gate with Open Collector OutputsNAND GateOpen Collector 7423: Expandable Dual 4-input NOR Gate with StrobeNOR Gate 7424: Quad 2-input NAND Gate gates with Schmitt-trigger line-receiver inputs.NAND Gate 7425: Dual 4-input NOR Gate with StrobeNOR Gate

7400 series ICs Flip-flops Counters Registers Memory devices and more…

7404 hex inverters

7410 Triple 3-input NAND gates

8-input NAND gate