ALL Interview Basics

8/21/2019 ALL Interview Basics

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Microprocessors &

Microcontrollers


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Microprocessor ?

A microprocessor is multi programmable clock driven

register basedsemiconductor device that isused to fetch , process and

execute a data withinfraction of seconds.


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Microprocessors

• CPU for Computers

• No RAM, ROM, I/O on CPU chip itself

• Example Intel!s x"#, Motorola$s #"%x%

3


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Microcontroller

• A smaller computer• Onchip RAM, ROM, I/O ports'''

• Example Motorola$s #"((, Intel$s "%)(,

*ilo+$s *" an PIC

Suresh.P.Nair , HOD - ECE , RCET 4


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Microprocessor vs.Microcontroller

Microprocessor• CPU is stanalone, RAM,

ROM, I/O, timer areseparate

• -esi+ner can ecie onthe amount of ROM, RAMan I/O ports'

•

Expansi.e

• ersatilit0

• 1eneralpurpose

Microcontroller• CPU, RAM, ROM, I/O an

timer are all on a sin+lechip

• 2ix amount of onchipROM, RAM, I/O ports

• 2or applications in 3hich

cost, po3er an space arecritical

• Not Expansi.e

• 4in+lepurpose5


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Microprocessor ?

A microprocessor is multi programmable clock driven

register basedsemiconductor device that isused to fetch , process and

execute a data withinfraction of seconds.


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56E "%") AN- I54 7U44E4

The 8085 is an 8-bit general purposemicroprocessor64K Byte of memory.It has 40 pins.

It can run at a maximum freuency of ! "#$.

%&&ress Bus.'(6 bit) *ata Bus. '8 bit)

+ontrol an& ,tatus ,ignals.oer supply an& freuency./xternally Initiate& ,ignals.,erial I1 ports.


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2la+ Re+ister

CYCYPP AC ACZZSSD0D0D1D1D2D2D3D3D4D4D5D5D6D6DD

The flags are affected by the arithmetic and logical

instruction


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Classi8cation of instructionset

According to word size orbyte size it is classied into

3 types. 1 byte instruction

! byte instruction and

3 byte instruction


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( 90te instruction

"t includes the #pcode and the#perand in the same byte.

$x. %#& A,'$x. (%) '

$x. A*A '

$x. +A


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Opcoe an operan

-he task to be performedis called #pcode

-he data to be operated iscalled #perand.


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: 90te instruction

-he rst byte species theoperation cod eand the next

byte species the operand$x. %&" A, 1

$x. /0" A, 3


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; 90te instruction

-he rst byte species theopcode and the next two

bytes species the 12 bitaddressdata.

$x. 4" 5, 6

$x. 7%) 6


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Timing Diagram is a graphical representation. Itrepresents the execution time taken by eachinstruction in a graphical format. The execution

time is represented in T-states.

Instruction Cycle: The time required to execute an instruction .

Machine Cycle: The time required to access the memory orinputoutput de!ices .

T-"tate:•The machine cycle and instruction cycle takesmultiple clock periods. •# portion of an operation carried out in one

system clock period is called as T-state. !"##e!$e% &' C.(")u# AP*EEE,+CET


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5imin+ ia+rams• The 8085 microprocessor has 7 basic machine

cycle. They are

1. Op-code Fetch cycle(4T or 6T).

. !emory read cycle ("T)

". !emory #rite cycle("T)

4. $%O read cycle("T)

5. $%O #rite cycle("T)6. $nterr&pt 'cno#lede cycle(6T or 1T)

7. *&s idle cycle

!"##e!$e% &' C.(")u# AP*EEE,+CET


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!"##e!$e% &' C.(")u# AP*EEE,+CET


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45A instructionex STA 526A


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It re;5 ;'memor0 rea>;5

='Memor0 3rite>;5


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Timing diagram for INC0H

• Fetcing te !pcode "#H fromte memor$ %&25H.

• 'ead te port address C0H from%&26H.

• 'ead te content of port C0H andsend it to te acc(m(lator.

• )et te content of port is 5*H.


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It re=5memor0 rea>;5

I/O rea>;5


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!+T

instr(ctionMacines

C$cles,&0T-&.instr(ction fetc,%T-

2.memor$ read ,/T-/.I! rite ,/T-


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Classi1cation ofInstr(ction Set

• -ata 5ransfer Instruction

• Arithmetic Instructions

• @o+ical Instructions

• 7ranchin+ Instructions

• Control Instructions


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IN5ER2ACIN1


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":)) PPI• 5he 255 chip is also calle as

3rogramma4le 3eriperal Interface'

• 5he Intel$s ":)) is esi+ne for use 3ithIntel$s "9it, (#9it an hi+her capa9ilit0microprocessors

• It is exi9le an economical'

CON5RO@ BOR-


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CON5RO@ BOR-RE1I45ER>CBR


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Modes of !peration of255

#it Set'eset,#S'- ModeSet'eset 4its in 3ort C

I! Mode Mode 0 ,Simple inp(to(tp(t- Mode & ,Handsae mode- Mode 2 ,#idirectional "ata

Transfer-


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7rite a program to initiali8e 255 in tecon1g(ration 4elo.,ass(me address of teC7 register as 2/H-.,&- 3ort A o(tp(t it andsae,2- 3ort # inp(t it andsae

,/- 3ort C) o(tp(t ,%-3ort C+ inp(t

Sol(tion

& 0 & 0 & & & 0 = AEH

M9I A:A*H ; LOAD CONTROL WORD

!+T 2/H ; SEND CONTROL WORD

Program:


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Find te control ord for te registerarrangementof te ports of Intel 255 for mode 0operation.3ort A !(tp(t: 3ort # !(tp(t: 3ort C+ !(tp(t: 3ort C) !(tp(t

Solution:

& 0 0 0 0 0 0 0 = 80H

The ontrol !or" regi#ter $or the a%o&e'ort# o$ (ntel 8)** i# 80H+

#asics of serial


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#asics of serialcomm(nication

&.Transmitter A parallelin, serialoutshift re+ister

2.'eceiver A serialin, paralleloutshift re+ister'

2

Parallel Tran#$er

TRANS,(TTER


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TRANS,(TTER

Reei&er


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IN5E@ ":)(U4AR5

+,$/' 2,3/O,O+


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+ ,$/' 2,3/O,O+

'2,3/O,O+ / 3$/

T/',!$TT/ (+'/T-Pro+ramma9le chip esi+ne fors0nchronous an as0nchronous serial atatransmission

:" pin -IP

Co.erts the parallel ata into a serial stream of 9its suita9le for serial

transmission' Recei.es a serial stream of 9its an con.ert

it into parallel ata 90tes to 9e rea 90 amicroprocessor'


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IN5E@ ":);/":)=

5IMER/COUN5ER


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INT*) 2;< =

3rogramma4le>e$4oard"ispla$

Interface


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"%)( 2amil0

• 5he "%)( is a su9set of the "%):

• 5he "%;( is a ROMless "%)( – A external ROM to it

– ou lose t3o ports, an lea.e onl0 : ports for I/Ooperations

36


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(nterru'tControl

CP-

./ RO,

)8 1RA,

OSC1u#

Control. (2O Port#

SerialPort

of 05&

T3D R3DP0 P P) P4


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"%)( Memor0 4tructure

E 5 t e r n a l

E3T (NT)8

S6R E 5 t e r n a l

P ,Data ,emor7

./ ./

EA =0

EA =

./

0/

051 i!r"!"/$r"##er Suresh PNair HOD ECE RCET 3

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ALL Interview Basics