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Lecture 

Attendance is a must( )ailing to attend !our lectures in

w%ic% attendance is collectedmay result in

s%ort attendance and !ail to sit in !inal e'ams

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4

&e'tboo*+ &e'tboo*

( M. Morris Mano and ,%arles . ime/ Logic and,om#uter Design )undamentals/ "econd Editionrentice Hall/ 2012.

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Mar*s Distribution

+ One midterm e'am  -3eig%t4 205

+ )inal e'am

(3eig%t4 605+ Assignments and ui88es

- 3eig%t4 205910:10;

+  Lab-3eig%t4 205

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6

,ontact uetta'ila.edu.#*

+

+  

+ O!!ice %ours4( 3ed =400 ( 11400

( &%rus =400-11400

( 061-=0?7-7?@

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De!inition o! a ,om#uter

+ An electronic Digital device w%ic% is ca#able o!

+ receiving in!ormation 9data; in a #articular !ormand o! #er!orming a seuence o! o#erations in

accordance wit% a #redetermined but variable seto! #rocedural instructions 9#rogram;

+ to #roduce a result in t%e !orm o! in!ormation orsignals.

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Digital "ystems4 E'am#leModern Digital ersonal

,om#uters 9,;&%e best *nown

e'am#le o! a digital

system  Most stri*ing

#ro#erty 4 generality

More Examples anduses?

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Digital "ystems4 More E'am#les

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ABALOC $AB&

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An Analog Electronic "ystem

+ A #ublic address system/ used to am#li!y sound so t%at it can

  be %eard by a large audience/ is an e'am#le o! analog+ electronics.

+ "ound waves/ w%ic% are analog in nature/ are #ic*ed u# by a

  micro#%one and converted to a small analog voltage called

+ t%e audio signal.+ &%is voltage varies continuously as t%e volume and !reuency

  o! t%e sound c%anges and is a##lied to t%e in#ut o! a linear

  am#li!ier.

+ &%e out#ut o! t%e am#li!ier/ w%ic% is an increased

  re#roduction o! in#ut voltage/ goes to t%e s#ea*er9s;. &%e

  s#ea*er c%anges t%e am#li!ied audio signal bac* to sound

  waves t%at %ave a muc% greater volume t%an t%e original

  sound waves #ic*ed u# by t%e micro#%one.

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An Analog Electronic "ystem

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A system using Digital and AnalogMet%ods

+ &%e com#act dis* 9,D; #layer is an e'am#le o! a system

+ in w%ic% bot% digital and analog circuits are used.

+ + Music in digital !orm is stored on t%e com#act dis*. A

+ laser diode o#tical system #ic*s u# t%e digital data !rom

+ t%e rotating dis* and trans!ers it to t%e digital-to-analog+ converter 9DA,;.

+ + &%e DA, c%anges t%e digital data into an analog signal

+ t%at is an electrical re#roduction o! t%e original music.

+ &%is signal is am#li!ied and sent to t%e s#ea*er.

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Digital "ystems4 Ceneral emar*s

+ A Digital "ystem mani#ulates discreteelementsFuantities o! in!ormation

+ 3%at are discrete elementsG

+ Discrete uantities o! in!ormation emerge !rom4  t%e nature o! t%e data being #rocessed  t%e data may be #ur#osely uanti8ed !rom continues

values

Discrete element o! in!ormation are re#resented indigital system by #%ysical uantities called signals."uc% as Electrical signals 4

oltages and current

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term digital com#uterFsystem emerged.+ Early com#uter systems were used mostly !or numeric

com#utations4 t%e discrete elements used were t%e digits/%ence t%e term digital com#uterFsystem emerged.

+

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&%e Digital "ystemsJ Al#%abet is Kinary

+ Digital "ystems use only one al#%abet wit% twosymbols 9digits; 0J and 1J 9%ence binary ;.

A binary digit is called a bit

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"witc%

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Kasic Digital "ystem "tructure+ -/ -entral

rocessing /nit+ 1ata at2 arit2metic

and logic o#erations+ -ontrol /nit ma3e

sure t2at t%e seuenceo! data #at% o#erationsis correct

+ 4torage no memory 5no system

+  #nput6output allowt2e system to interact wit%

t%e outside world

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Logic Cates+ How does t%e digital circuit #rocess t%e binary

in!ormationG+ As mentioned earlier/ t%e digital circuits are

designed to wor* wit% binary numbers.

+ Logic Cates w%ic% are t%e Kasic building bloc*s o!a com#le' digital system w%ic% #er!orm sim#lebut uniue o#erations on t%e binary or digitalin!ormation.

+ &%e basic Logic Cates are t%e ABD Cate/ OCate and t%e BO& Cate.

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Logic Cates+ Eac% o! t%ese t%ree gates #er!orms uniue logical

o#erations on t%e in!ormation a##lied at t%eout#uts. &%e result o! t%e o#eration is availableon t%e out#ut o! t%e gate.

+ Ot%er gates t%at are also !reuently used areBABD/ BO/ NO and NBO. &%e !our gates aresymbolically re#resented in t%e diagram.

+ All t%ese gates are available in t%e !orm o!

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Logic Cates+ &%e Logic gates by t%emselves are not able to do

anyt%ing use!ul. &%ese gates %ave to beconnected toget%er to !orm a circuit w%ic% isable to #er!orm some use!ul !unction. A circuit

!ormed by t%e combination o! logic gates is *nownas a combinational circuit.

+ An Adder combination circuit is s%own in t%ediagram.

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Adder ,ombinational ,ircuit

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Sum

Carry

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Adder ,ombinational ,ircuit+ An Adder circuit is !ormed by t%e combination o!

ABD/ O and NO gates and is able to add twosingle bit binary numbers.

+ ,ombinational circuits #er!orm an o#eration on

t%e in#ut binary in!ormation and results in anout#ut w%ic% is almost instantaneous.

+ Many o! t%ese combinational circuits t%at#er!orm a s#eci!ic !unction suc% as addition are

available as M"<

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)unctional Devices+ ,ommonly used !unctional

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"euential ,ircuits+ Digital systems are being used in a wide variety o!

a##lications. A large number o! t%ese digitalsystems generate an out#ut based on not only t%ecurrent in!ormation but some #reviously storedin!ormation.

+ ,onsider a timer circuit/ counting in reverse !rom10 to 0. &%e timer circuit decrements t%e count by1 eac% time it receives an in#ut signal. &%e new

count value is de#endent on t%e #revious countvalue.

+ ,onsider t%e bloc* diagram o! a "euential circuit.

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Kloc* Diagram o! a "euential,ircuit

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"euential ,ircuit+ &%e "euential circuit consists o! a ,ombinational

#art and a memory element.+ ,onsider t%e timer o! a microwave oven. ou *ey in

t%e time to coo* your !avourite dis%.

+ &%e microwave dis#lay unit dis#lays t%e coo*ing time.+ &%e memory element o! t%e microwave ovenseuential circuit stores t%e coo*ing time.

+ &%e coo*ing time is decremented by 1 a!ter every

second w%en a new in#ut signal is received at t%ein#ut o! t%e combinational #art o! t%e "euentialcircuit.

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"euential ,ircuit+ $ltimately/ w%en t%e coo*ing time decrements to 8ero and t%e

memory element stores 8ero / t%e ne't in#ut signal sounds an alarmand turns t%e microwave o!!.

+ A tra!!ic signal controller o#erates in a similar manner.

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Memory+ Memory is an im#ortant reuirement o! a digital system.

Kesides its use to im#lement seuential circuits/ largememory is reuired to store in!ormation in com#utersystems. Essentially memory is o! two ty#es.

+ AM 9andom Access Memory; w%ic% also stored

in!ormation to be read or modi!ied.+ AMs are volatile/ t%at is i! t%e #ower is turned o!!/ t%e

contents stored in t%e memory are lost.

+ OM 9ead-Only Memory; as t%e name s#eci!ies allows

only read o#erations. Bo new in!ormation is allowed to bewritten into t%e memory.

+ OMs are non-volatile and retain t%e in!ormation even i!t%e #ower is turned o!!.

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