map notes_ chapter 1

7/25/2019 MAP Notes_ CHapter 1

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MAP notes

Chapter 1: Basics of Microprocessor

Q1. List features of 8085 microprocessor.

It is a 8 bit microprocessor.

It is manufactured with N-M! techno"o#$.

It has 1%-bit address bus and hence can address up to &'1% ( %55)% b$tes *%+, memor$

"ocations throu#h A0 -A15

/he first 8 "ines of address bus and 8 "ines of data bus are mu"tip"eed A0 2 A3

ata bus is a #roup of 8 "ines 0 2 3

It supports eterna" interrupt re4uest.

A 1% bit pro#ram counter *P

A 1% bit stac6 pointer *!P

!i 8-bit #enera" purpose re#ister arran#ed in pairs7 9 :L.

It re4uires a si#na" ;5< power supp"$ and operates at ).& M:= sin#"e phase c"oc6.

It is enc"osed with +0 pins IP *ua" in "ine pac6a#e.

Q&. raw the Architecture of 8085 Microprocessor.

Q). 9p"ain the re#ister or#ani>ation of 8085.

/hese are si #enera" purpose re#isters name"$ 9 : L a"" 8 bit in si>e. /he$ are used in

#enera" to store 8 bit data temporari"$. !ometimes durin# ca"cu"ations to store the intermediate


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?a"ue sometimes to store the resu"t of an$ ca"cu"ations etc. /hese si re#isters can a"so be used to

store 1% bit data b$ usin# them in pairs as 9 :L. @hen used in pairs the$ are a"so used to

store addresses of memor$ "ocations which are 1% bits.

Accumu"ator is a"so an 8 bit re#ister which is used to store temporar$ data. ut it has a"so

other tas6s. It is the most important re#ister of a microprocessor and e?er$ microprocessor

consists of an accumu"ator. It is used b$ the AL *arithmetic "o#ic unit durin# addition or

subtraction operation the resu"t is stored in the accumu"ator. After which we store it an$where we

want. 9#. A instruction wi"" add the content of re#ister *where temporar$ data is stored

and accumu"ator and store the resu"t in the accumu"ator itse"f.

/his is an 8 bit temporar$ re#ister which is not used b$ the user but on"$ used b$ the

microprocessor itse"f to store temporar$ data.

B"a# re#ister is norma""$ used to ref"ect the resu"t of some operations or to contro" some

operations. ut of the 8 bits on"$ 5 bits are used. 9ach bit is ca""ed as a f"a# which ref"ects the

resu"t of some operation or contro"s some operations.

/here are two re#isters which actua""$ act as pointers. Pro#ram counter points to the net

memor$ address whi"e current instruction is in eecution sta#e.

9#. &000:7 M< A

&001:7 M


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Q+. !tate two uses of Accumu"ator in 8085.

1. Accumu"ator is a"so an 8 bit re#ister which is used to store temporar$ data

&. It is used b$ the AL *arithmetic "o#ic unit durin# addition or subtraction operation the

resu"t is stored in the accumu"ator.

Q5. List the Limitation f 8085 Microprocessor.

i. /he 8085 is an 8-bit microprocessor hence it can perform operation on"$ on two 8-bit

numbers.

ii. /he 8085 has 1% bit address "ines and 8-bit data "ines.

iii. /he 8085 can address maimum memor$ of %+ ,b *&'1%.

i?. /he 8085 cannot perform an$ operation on A!II number.

?. /he 8085 cannot perform mu"tip"ication and di?ision of numbers.

?i. /he 8085 cannot perform subtraction mu"tip"ication and di?ision of number.

?ii. /he 8085 cannot transfer the data direct"$ from one memor$ to another memor$.

?iii. /he 8085 cannot perform the pipe"inin# of instruction.

Q%. 9p"ain the 9?o"ution of Microprocessors.

Inte" de?e"oped and de"i?ered the first commercia""$ ?iab"e microprocessor wa$ bac6 in the ear"$1C30Ds7 the +00+ and +0+0 de?ices. /he +00+ was not ?er$ powerfu" and a"" it cou"d do was add

and subtract with +-bit data on"$ at a time. Inte" rapid"$ fo""owed their +-bit offerin#s with their

8008 and 8080 ei#ht-bit Ps. /his was notthe wor"dDs first Epersona" computerF. Inte" started

facin# competition from Motoro"a M! /echno"o#$ and an upstart compan$ formed b$

dis#runt"ed Inte" emp"o$ees =i"o#. /o compete Inte" produced the 8085 microprocessor. /o the

software en#ineer the 8085 was essentia""$ the same as the 8080. :owe?er the 8085 had "ots of

hardware impro?ements that made it easier to desi#n into a circuit. /he first microprocessor to

ma6e a rea" sp"ash in the mar6et was the Inte" 8088 introduced in 1C3C and incorporated into the

IM P *which appeared around 1C8& for the first time and then came the phenomenon 808%

and then the$ mo?ed to the 80&8% to the 80)8% to the 80+8% to the Pentium to the Pentium II tothe Pentium III to the Pentium +. /he Pentium + can eecute an$ piece of code that ran on the

ori#ina" 808% but it does it about 5000 times fasterG.

Q3. raw the f"a# re#ister format of 8085 microprocessor and ep"ain a"" the f"a#s.

Carry Flag:


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urin# an addition operation if a carr$ is #enerated from the M! or durin# a subtraction

operation a borrow is #enerated carr$ f"a# sets indicatin# a carr$ or borrow respecti?e"$.

/herefore when

B ( 1H carr$ is #enerated

B ( 0H carr$ not #enerated

Auxiliary carry flag:

urin# an addition operation if a carr$ is #enerated from the "ower nibb"e to the hi#her nibb"e

then A f"a# sets.

Parity flag:

@hen an addition subtraction mu"tip"ication di?ision or an$ "o#ica" operation ta6es p"ace

then dependin# on the resu"t the parit$ f"a# #ets affected.

p chec6s the 8 L!Ds of the resu"t7

If the number of oneDs in the 8 L!Ds are 0J&J+J%J8 then the parit$ f"a# sets i.e. PB ( 1

indicatin# e?en parit$

If the number of oneDs in the 8 L!Ds are 1J)J5J3 then the parit$ f"a# resets i.e. PB ( 0

indicatin# odd parit$

Zero flag:

@hene?er an$ arithmetic or "o#ica" operation ta6es p"ace and the resu"t is 0 then >ero f"a# sets

to indicate that the resu"t is 0 i.e. =B ( 1.

Eg:Let A ( 80:

( 80:

! instruction is eecuted. /he resu"t obtained is 00: in A re#ister. @hen p chec6s this

it has to ref"ect it somewhere that the resu"t is >ero so it ref"ects in bit 3 which is reser?ed for

>ero f"a# b$ settin# its ?a"ue to 1 i.e. =B ( 1

Sign flag :

@hene?er the resu"t of an$ arithmetic operation is ne#ati?e the si#n f"a# sets i.e. !B ( 1


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Q8. ifferentiate between 8085 and 808%. *An$ + points

8085 8086

8 bit Microprocessor 1% bit Microprocessor

Accumu"ator si>e is 8 bits Accumu"ator si>e is 1% bits

!i>e of AL is 8bits !i>e of AL is 1% bits

!i>e of data bus is 8 bits !i>e of data bus is 1% bits

!i>e of address bus is 1% bits !i>e of address bus is &0 bits

Memor$ accessib"e is %+ ,b Memor$ accessib"e is 1 Mb

Architecture is a sin#"e unit Architecture is di?ided into & units

/here is no pipe"inin# Pipe"inin# concept introduced

/here is no 4ueue re#ister % b$te 4ueue re#ister a?ai"ab"e in the I

No memor$ se#mentation Memor$ is di?ided into se#ments as7 ! !

9! !!

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