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Question 1. What is a computer?
A computer may be defined as a machine which accepts data from
an input device, processes it by performing arithmetical and
logic operations in accordance with a program of instructions
and returns the results through an output unit.
A computer is basically an electronic machine operating on
current.
1
Computer system
Computer System
Book I: computer system fundamentals.
Chapter 1: INTRODUCTION TO COMPUTER.
Question 1. What is a computer?
A computer may be defined as a machine which accepts data from
an input device, processes it by performing arithmetical and
logic operations in accordance with a program of instructions
and returns the results through an output unit.
A computer is basically an electronic machine operating on
current.
2
Question 2. Components of a Computer system?
A computer system comprises of the following components:
1. Central Processing Unit (CPU).
- CPU is the heart of the whole sys
- CPU consists of the :
• control unit (CU)
• arithmetic logic unit (ALU)
• accumulator (ACC)
• program counter (PC)
• instruction register (IR)
• memory address register (MAR)
• memory data register (MDR)
• status register (SR)
• general purpose register
- The function of each components of CPU:
• Control unit:
control and co_ordinate all hardware
functions of the CS.
examine and decode all program instructions
to the computer and initiate their execution
by sending the appropriate signals.
• ALU:
performs all arithmetic and logic comparision two
values functions required by computer.
• ACC:
holds the first operand of the temporary
result of the ALU.
• PC:
contains the add of the next instruction to
be excuted.
• IR:
contains the current instruction to be
executed.
Main memory
• MAR:
holds the address location to or from which
data is to be transferred
• MDR:
contains the data to be written to or read
out of the addressed location.
• SR:
keeps track of the status of the
accumalator.
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• G eneral Purpose Regi ste r:
for genera l purpose procedures.
Please refe r to di ram for an illu stra tin of the basi
ag c
com ponents of the CPU .
CPU
I
N
T Contro l unit
E Arithm eti Log i Uni
c c t
R
N Accum ul
ator
A Program Couter
L
to m ai
n
Instru cti Regi
on ste r
B
U m em ory
S
M em ory Address Registe r
M em ory D ata Registe r
Status Registe r
G eneral Purpose Registe r
Basi com ponents of a CPU .
c
Contro l Unit
Inpu t Unit ALU
O utput Unit
M ai
n M em ory
Backi Storage
ng
Contro l si gna ls
D ata flow
Com ponents of a CS.
2. Input uni ts
- U sed to enter data( raw unprocessed facts) and
i stru cti s to the com put
n on er.
3. O utput units
4
- U sed f del
or everi ng the processed resu lt from the
com put er i usef l for .
n u m
4. Backi storage uni
ng ts
- Backi storage uni need for hi capaci data
ng ts gh ty
storage devi ces that can store data i a m or
n e
per anent f m for l te r retri ra l, updati
m or a e ng and
re fe renci .
ng
- Backi storage i al call
ng s so ed secondary storage
externa l storage and auxilia ry storage.
Chapter 2: MICOPROCESSOR.
Question 1. Cache Memory?
- Cache memory is a small amount of very fast store with
faster access time than the main memory.
- Cache memory is used to temporaryty store data
instructions that are likely to be retrieved many
times, thus speeds up the processing of data.
- Sits between main storage and the processor acting as
holding area through which all data and instructions
pass.
- Old data in the cache memory is over written by new
then cache is full.
Question 2. Virtual Memory?
- Virtual memory makes use of both the main memory and
backing store.
- In a virtual memory sys, each user has the illusion
that his program is in the main memory all the time.
- The sys maintains this illusion by keeping some of the
“unused” portion of the program’s code and data on a
backing store device which is usually magnetic disk
- The movement of the unused portion from the backing
store to the mian memory is transparent to the users.
- Please refer to diagram for virtual memory.
Backing Store Main Memory
A3
A2
A1
A3
A2 A1
Virtual Memory
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Chapter 3: BATCH/ ONLINE AND REAL TIME PROCESSING SYSTEM.
Question 1. Batch Processing System?
- Def: Computer processing does not begin until all the
input data has been collected and grouped together
called Batched Generally data is accumulated for a
certain period of time or unitl a certain quantity.
- Ads:
Response time is not critical.
Need to process large volumn of data.
Computer efficiency is more important than
response time.
- Dis:
Time between recording and processing of
source document is long
Rereen normally required if errors are
encountered.
Data is not current.
Error correction is more difficult.
Question 2. Online Processing System?
- Def: Inputs data enters the computer directly as soon
as it is being transacted. There information will be
processed immediately and updated into the master
file.
- Ads:
Enter availability of information for
decision making.
More accurate data capture.
Schedules suits user.
- Dis:
CPU time is used less efficiently.
Random arrival of transactions, terminal
operator process each transaction
separately.
More expensive than batch processing.
Question 3. Real Time Processing System?
- Def: One which controls the environment by receiving
data processing them and returning results
sufficiently quickly to affect the functioning of the
environment at that time.
- Ads:
Response time is very critical and
sufficient quick.
- Dis:
Expensive hardware & software.
Very complex in terms of hardware &
software.
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Chapter 4: PRINTERS AND TERMINALS.
Question 1. Classification of printers?
1. Classifying printers according to speed.
a. Serial printers
Slow printers that print one character at a time.
Eg: Dot matrix printers
Daisywheel printers
b. Line printers
Medium to high speed printers that can print in excess of
2000 lines per minute.
Eg: Chain Printers
Band Printers
Drum Printers
2. Calssifying printers according to method of printing
a. Impact printers
Use hammers or prints to strike a print rebbon in order
to form the character on the paper.
b. Non impact printers
Use more silent methods of printing.
Eg: Thermal printers
Ink Jet printers
Lazers printers
3. Classifying printers according to print quality
Kinds of quality printers
Draft quality
Near letter quality(NLQ)
Letter quality
Graphic quality
Question 2. Describe some types of printer?
1. According to speed:
a. Dot matrix printer
- Serial impact printers that can print draft, near
letter quality and a limited amount of graphics.
- The print resolution is generally lower than lazer
printers.
b. Daisywheel printers
- Are serial impact printers, the speed of a daisywheel
printer is slow(2055 characters per second), noisy in
operation.
- The print head has the letters arranged at the end of
spokes round a central hub.
c. Chain printers
- The chains printers has its characters set rapidly
rotating on a print chain.
d. Band printers
- The band printer has rotating scalloped steel band.
e. Drum printers
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- Are l i ne prin te rs , the pr in t character are ra i sed in
bands around a heavy metal drum which rotates at very
high speed.
- The pr in t hammers str i ke the paper and a prin t r ibbon
against an apropr ia te character on the l i ne . An ent i re
l i ne of the same character is pr in ted on one rotat i on
of the drum.
f. Thermal pr in te rs
- Uses specia l heat sensi t i v e paper and a matr ix of
pr in t wires that become hot when exposed to an
elect r i c current . The heated wires come in to close
contact with the paper, burning the image of the
character onto i t .
- The more advanced thermal pr in te rs are using thermal
trans fer prin t i ng .
- They have a specia l heat sensi t i ve r ibbon and a pr in t
head with wires that become hot when a currents is
appl ied .
- The heat from the pr in t wires causes the ink from the
r ibbon to fuse to a piece of regular paper.
g. In l Je t Pr in te rs
- The ink je t pr in ts by using a smal l droplet generator
to break specia l inks into t iny drops, which are then
forced towards a paper supply .
h. Lazer pr in te rs
- Using a photoconduct ive drum.
- A lazer i s then used to wri te the image of the
character onto the drum.
- After exposure to the lazer , the drum rotates through
a develop ing stat i on , picks up toner and transfe rs i t
to the paper.
- The character is fused onto the paper by heat .
i. Ion deposi t i on pr in te rs
- Ions are created in a cavi ty , and di rec ted
elect r i c a l l y through an or i f i c e onto the die lec t r i c
surface of a rotat i ng cyl i nder .
- The requi red characters are formed as an elect r i c
charge image on the cyl i nders sur face .
- Toner i s the appl i ed to the charged image and
trans fer red to the paper on which i t i s trans f i xed by
pressure(co ld fus ion) .
j. Elect ros ta t i c pr in te rs
- Letterheads and logos are created elect ros ta t i c a l l y
f rom a changeable metal cyl i nder .
k. Magnetic prin te rs
- A drum in the pr in te r has a surface that can be coated
with sows of t iny spots of magnetion by means of
thousands of minute record ing heads.
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- As the drum rotates it becomes covered with these
magnetic spots so as to from a latent image of the
page to be printed.
- Dry ink partic les are brought into contact with the
drum’s surface and these adthere to the magnetised
spots. The ink was then pressunal on to the surface
and subsequently transferred onto the paper.
Question 3. Characteristics of a page printers?
- Speed
- Characters sets
- Copies
- Intel l i gence
- Output
Chapter 5: DATA STORAGE MEDIA.
Question 1. Data storage Requirements Characteristics?
- Low access time: fast speed
- Storage capacity: much enough
- Interchangeabil i ty : can be change easily
- Security: safe enough
- Transfer rate: fast enough
- Cost: economic
Question 2. Magnetic disks?
- This comprises a drive unit onto which one or perhaps
two magnetic disk cartr idges are loaded.
- The drive consists of a control unit and a spindle
housing that rotates continuously when switch on.
- The cartr idge are loaded by the operator so as to
provide the data currently needed for the job in hand.
- Bach tracks is devided up into sectors(often 4 or 8),
sectors are read or written or more at a time as
blocks by means of a read.
- There are usually one head for each surface, all the
heads are moved.
- Sunchronously across the tracks.
- Once in posit ion all the data on the equiradial tracks
can be read or written without further movement of the
heads.
- Cylinder is a set of equiradial tracks.
- A cartr idge comprises several f lat disks mounted on a
central sprindle. When mounted it rotates at a high
speed enabling data to be read from or written to it .
The data is recorded magnetical ly on both surfaces of
each disk in the form of concertr ic tracks.
•
Certain models of disk units also have a
number of f ixed read/write heads in addit ion
to the movable heads.
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The f ixed head are posit ioned permanently
over certain of the outer tracks, there
being one head per track, so cl imimating the
need for head movement.
- The heads are very close disk surface.
- Curshion of air carried by the rotat ing disk.
Question 3. Winchester disks( hard disks )?
- Comprises a number of platters(disks) permanently into
an airt ight enclosure.
- All dust is excluded thus perimit ing the read/write
heads to be posit ioned even closer to the surfaces and
so enabling greater recording densit ies to be
employed.
- The disks have greater storage capacity and a higher
rate of data transger.
- I t has the lubricated surfaces allowing the heads
“land” when the platters cease to rotate, so
eliminating head crashes.
- Winchester platters are either 14 in, 8 in, 5¼ in or
3½ in diameter.
Question 4. Floppy disks?
- Diskettes, generally cal led f loppy disks, are single
disks made of f lexible plast ic and permanently housed
is an envelope.
- The data on f loppy disks is in concentric tracks on
the outer part of the surfaces and access to it is via
slot in the envelope.
- The most com mon size are 3½ in, 5¼in, and 8 in
diameter disks, the 3½ in disks have the advantages of
a shutter.
- Floppy disks may be either single or double sided and
of course the drive needs to be correspondingly
equipped.
- Both the drives and the f loppy disks themselves are
inexpensive with the result that they have come into
extensive used by small business and home computer
buffs.
- The range of capacit ies is from 1/4 to 2 megabytes and
transfer rates around 125 to 250 ki lobytes per
seconds.
Question 5. Optical disks?
- Optical disk are comparatively new development for
data storage.
- Optical disks consist of a single removable glass,
plast ic or metal disk coated on one side with
tel lur ium and protected by a 1 m layer or transpacent
m
plast ic .
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- The disk diameters are mostly between 8 in and 14 in
they rotate on a spindle in a similar fashion to
magnetic disks.
- The data is recorded in the form of minute pits burned
into the tel l iur ium coating by a f inely- focused lazer
beam.
- Optical disks hold between 0.7 and GBs, this is about
20 times greater than magnetic dis cartr idges.
- The data is read by a low power laser beam which moved
across the surface and is ref lected into a photo cell .
- Optical disks rotate mostly at 1500 r.p.m which,
al lowing for the movement of the laser unti , given
access time of between 16 & 500 ms and data transfer
rates of 0.6 to 3 MVs per second.
- The draw back of optical disks is that the data cannot
be erased so making them non-rewriteable.
Question 6. Mass storage media?
- Mass storage media is a high capacity disk system as
when necessary by transferr ing data from a number of
“data cartr idges” house in cel ls .
- Each cartr idge consists of a 3 in wide magnetic modium
inside a protective cover
- In order to load the disk system, the data cartr idges
are moved automatical ly from the cells .
- A typical system consists of 9440 cartr idges giving a
storage capacity of 472000 mill ion bytes.
Question 7. Magnetic drums?
- A magnetic drum consists of a cyl inder upon the
surface of which data is stored in magnetic form in
tracks running around its circumference, each track
has its own read/write head.
- A typical magnetic drum has 800 tracks each capable of
holding 5000 bytes.
Question 8. Charge_coupled Device Memory (CCD)?
- CCD consists of thousands tiny metal squares each
capable of holding an electr ic charge, thus
representing a bit .
- The squares are in the form of an array 64 x 64
holding 4096 bits.
- I t is very impact.
- CCD is volate l i ty storage.
Question 9. Magnetic Bubble Memory?
- A thin wayer of magnetic garnet is capable of
containing tiny domains or cyl inders of magnetism,
called bubbles.
- By erasing unwanted bubbles, the resultant presence of
a bubbles represent a 1 or a 0 bit .
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- The main ads are low power consumption, compactness,
robustness rel iabi l i t y and non-voli t i l i t y .
Question 10. Megnetic tape?
- The magnetic tape usage is now more as a backup medium
rather than a primary method of backing storage.
- I t is often used as a depositony for disk dumped from
f ixed data storage.
- I t is in reel ls of up 3600 feet and is made of Mylar
plast ic tape, 1/2 in wide and coated with a magnetic
material on one side.
- The data is read from one read and written to another.
- A reel of tape is loaded on a magnetic tape drive, and
so as many drives are needed as reels during a
processing run.
- I t is used as a backing medium than a primary method
of backing storage.
- The seconds usually have to be sequence where store in
magnetic tape.
Chapter 7: COMPUTER FILES.
Question 1. File Processes?
1. Sorting
a. The records in logical f i le are brought into some
sequence as determined by key in the records.
b. A computer is capable of sort ing record into a
“nested” sequence.
c. Sorting is done by a “sort ing generator”. This is part
of the computer’s software and comprises several
sophist icated sort ing techniques that are called into
use according to the f i le and the sort requirements.
d. The need of sort ing has dimished in l ine with the
demise of magnetic tape as backing storage.
2. Merging
- Merging implies that two or more f i les in the same
sequence are combined into one f i le .
a. Fi le merging
Two or more separate f i les of similar
seconds and in the same sequence are
marged together so as to form one f i le .
b. Record merging
The records from two or more “input”
f i les , usually in the same sequence,
are combined one record in the output
f i le .
3. Matching
a. Two or more input f i les (general ly in the same
sequence) are compared records against record in order
to ensure that there is a complete set of records for
each key.
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b. Masmatched records are highl ighted for subsequent
action
4. Sum manizing
a. Records with the same key in one f i le are accumulated
together to form one record in the output f i le .
b. Sum manizing usually applies to a f i le presorted into a
certain sequence and the resultant f i le is in the same
sequence.
c. Records to be sum marized are generally of a similar
type.
5. Searching
a. Searching is looking for records with certain keys or
holding certain data and in some way making a note of
these.
b. An instance is a search for and count of all records
with a debt balance of above a certain amount.
6. Information retr ieval
a. Information retr ieval is the process that involves the
bringing together of data from several f i les .
b. Data may also be extracted from several f i les and
combined before being presented as information.
Chapter 8: DIRECT ACCESS FILE ORGANIZATION AND STRUCTURES.
Question 1. Storage and Access Modes?
There are 3 principal modes for storing and accessing accords on
a disk or drum:
1. Serial mode:
- The record are stored contigously regardless of their
keys
- The sole way of accessing serial seconds is to search
through the complete f i le start ing with the f i rst
record.
- I t is sometimes possible to parti t ion a serial f i les
thus reducing the search time by start ing the search
at the beginning of a known parti t ion.
- A serial f i le is normally of a temporary nature
awaiting sort ing into a useful sequence.
2. Sequential mode:
- direct access sequential mode normally involves
accessing sequential a f i le that is stored
sequential ly .
- sequential mode is often associated with a master f i le
held in a certain sequence and updated by a
transaction f i le sorted into the same sequence.
3. Indexed_sequential / select ive_sequential mode
- Indexed_sequential is a mode of storage where by
records are held sequential ly and accessed
select ively.
- Groups of unrequired records are skipped past.
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- Indexed sequential f i lesmay also be accessed
haphazandly.
4. Random modes:
- Each record is stored in a location determind from the
second’s key by means of an add generation algorithm.
- The only erric ient way to f ind a record is to use the
algorithm
- Random mode is applicable to master f i les
• Ads of random modes
No index is required thus saving storage
space
I t is a fast access method because l i t t l e or
no searching is involved
Transaction do not need storing, thus saving
time
New records are easi ly insert ly into the
random f i le provided they are not excessive
in number
• Dis
The main problem with the random mode is in
achieving a uniform spread of records over
the storage are al located to the f i le
Question 2. Direct Access Addressing?
- The key of record is used to identi fy by record
- The key of record also is used to decide its storage
location(or address)
1. Self addressing:
- Self addressing is a straight forwards method because
a record’s address is equal to its key’s value
- The f i le is inevitably stored in key sequence
• Ads of self addressing
I t leads direct ly to the wanted record
No indexing or searching is required
The key itsel f need not necessari ly be held
within the stored record- although it
generally is
• Dis
The storage space per second has to be the
same
When records one missing, storage locations
related to its must be left empty
2. Self addressing with key conversion
- This method a basical ly similar to self addressing
except that the key required a l i t t l e processing to
turn it into the record’s address
- This leads to either a pricise address
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3. Matrix addressing
- In somes case, it is necessary to f ind the add of a
record held within a multi dimensional matrix of
record it ’ s called matrix addressing.
Question 3. Direct Access Searching?
- Where as addressing determines the location of a
record by using algori thmic methods, searching f inds
the record by scanning groups of records, and index,
or both.
- ]The simplest method is to examine every record a f i le
unti l the required record is found a shortcut is
generally desiable.
1. Indexed sequential searching
- A cyl inder index is created to hold the highest
cyl inder’s key
- Associated with each cyl inder is a block index holding
the highest key in each block within that cyl inder
- When searching for a record’s key in the index
The cyl inder index is examined key_by_key
unti l one is found that is larger than or
equal to the wanted key this directs the
search to the appropriate block index
The block index a similar ly examined and the
search
The block is searched record by record unti l
the wanted record is found
2. Binary searching( binary chopping )
- The key in the index to be binary search must be in
sequence and form a complete set
- The search starts at the midpoint of the index and
then moves half way to the left or right(down or up)
depending upon whether are wanted key is less than or
greater than the midpoint key
- In pracice, the index is unlikely to as convenient as
this example because it is not always possible to
exactly halve each sucessive move(complete exact
holvingis possible only when the total number of keys
in the index is 20- 1)
- The average number of examinations comparisons is
(log 2k)1 ( k is the number of keys in the index)
3. Block searching
- A block is a subdivis ion of an index. A block is
devised to contain, roughly the square root of the
number of keys in the whole index
- The search is f i rst through the block index to f ind
the appropriate block and then through this to f ind
the wanted key
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- The average number of examinations is square – root –
k
(k is the total number of keys)
4. Balanced binary tree searching
- A binary tree is a relat ionship of keys such that the
examination of any key leads to one of two other keys
- The binary tree is actual ly in the form of an index
containing all the keys together with a directory
showing the braches stemming left and right from each
key
- Binary tree searching is suitable for an unsequenced
f i le
- The search is similar to binary searching in that each
key examination holves the rinaining keys, on average
Chapter 11: INTRODUCTION TO ARTIFICAL INTELLIGENCE.
Question 1. AI?
Atif ic ia l Intel l igence
I t has three braches
1. Expert systems (or knowledge- base system)
- ESs are programs that contain the knowledge of human
expert, encoded so a computer can understand it with
encated- knowledge seasoning machinism, ES can tackle
problem that are beyond the seach of conventional ly
program med computers.
2. Natural language systems (everyday native language)
- Natural language systems are programs that understand
the native language of the user, such as E
- The most popular natural language systems are those
that act as interfaces to data bases
3. Simple perception systems (for vision, speed and touch)
- They can interpret visual scenes and decide i f object
meet inspection standards and quali ty control
cri ter ia , or move a robot to the proper location ot
grasp a part for manufacturing
Question 2. Who does the updates?
- Updating the knowledge bases is very dif f i rent when
with updating databases because of the dif ference in
the type of information and in the cause and effect
relat ionship contained in knowledge bases
- A knowledge in the area, when databases may be
modified by a normal users
Chapter 12: EXPERT SYSTEMS.
Question 1. What is an ES( Expert system )?
An ES is a knowledge-intersive program that solves a problem
that normally requires human expertise
• Characterist ics of ESs
- They solve problems as well as or better than human
experts
- They use knowledge in the form of rules or frames
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- They can consider multiple hypotheses simultaneouly
• Types of ES
- An assistant
Is the leasts expert or lowest level ESs
I t helps a decision maker by doing routine
analysis and porting out those portion of
the work where human expertise is required
- A col leage
The new discusses the problem unti l a joint
decission is reached
When system is going wrong, the user adds
more information to get it back on track
- True ES
Is a system that advises the user without
question
There are no practical areas today in which
decission
Question 2. A ES Life Cycle (ESLC)?
- An accepted SDLC for expert systems has yet to be
developed
There are 6 phases l i fe cycle in an ES
1. Phase1 – Selection of an Appropriate Problem
- Phase 1 involves f inding an appropriate problem for an
ES, indenti fy ing an expert to contribute the expertise
- Establ ishing a prel iminary approach
- Analysing the cost and benefitsPreparing a development
plan
2. Phase 2 – Development of a prototype system
- A prototype sys is a small version of an ES designed
to test assumptions about how to encode the facts, the
relat ionships and the knowledge of experts
- The prototype permits the knowledge engineer to gain
the expert’s com mitment and to develop a deeper
understanding of the f ie ld of expertise
- Other subtasks in this phase:
Learning about the domain and the task
Specifying performance cri ter ia
Selecting an ES building tool
Developing an implementation plan
Developing a detai led design for a complete
system
3. Phase 3 – Development of a Complete System
- The main work in this phase is the addit ion of a very
large number of rules
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- The knowledge base has to be expanded to ful l
knowledge base appropriate to the real world and the
user interface has to be developed
2. Phase 4 – Evaluation of the system
- This phase involves test ing the system against the
performance establ ised in earl ier stages
5. Phase 5 – Intergrat ion of the system
- The ES has to be intergrated into the data f low and
work patterns of the organization
- In this stage, the expert system has to be interfaced
with other databases, instruments and hardware.
6. Phase 6 – Maintenance of the system
- The maintenance of the ES involves is updating,
charging in the system when operating. When operating,
more problems occur in the system, so it is necessary
to continue take care the system by expert in a f ix
period of time
- So expert system, are so complex that in a few year
the maintenance costs wil l equal the development
costs.
BOOK II: Computer systems architecture.
Chapter 1 – 2: NUMBER BASES.
Question 1. Common number bases used in computer hardware
operation?
• Decimal(denary) system:
- The base is ten – there are 10 dif ferent symbols, the
digits 0, 1, 2, etc. . .upto 9
- To represent value less than ten involves only one
digit larger values need two or more digits
• Binary system
- The base must be two, with only the digits 0 and 1
available
- To show values of two or ever require two or more
binary digits
• Octal system
- Octal system has eight as its base, it uses the symbol
0, 1, 2 up to 7 only
- Two or more digits are needed for values of eight and
above
• Hexadecimal system(hex)
- Hexadecimal system has sixteen as its base, it use the
symbols 0, 1, 2.. . ,9 & A, B, C, D, E, F, to stand for
the “digits” ten, eleven, twelve, thir teen, fourteen,
f i f teen.
Question 2. Converting from Bases To Bases?
1. Change the decimal
- Binary:
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Eg. (2559) 10
2559 1
1279 1
639 1
319 1
159 1
79 1
(2559)10 = (10111111111)2
39 1
19 1
9 1
4 0
2 1
0 0
- Octal:
7690 8
49 96,1 8
10 16 120 8
2 1 40 15 8
0 7 1
(7690)10 =
(17012)8
- Hexadecimal:
6396 16
159 399 16
156 79 24 16
1 1 8 1
C F
(6369)10 = (CF81)16
2. Convert to others from binary
- To decimal
(101010)2 (?)10
1.25 + 0.24 + 1.23 + 0.22 + 1.21 + 0.20 = 42
(101010)2 = (42)10
- To octal
100101101
1 step change into denary
st
19
= 1.2 + 1.25 + 1.23 + 1.22 + 1.20
8
= 256 + 32 + 8 + 4 +1
=(301)10
2 step: convert to octal
nd
301 8
61 37 8
5 5 4
(301)10 = (455)8 (100101101)2
= (455)8
- To hexadecimal
110111011011
1st step
= 1.211 + 1.210 + 1.28 + 1.27 + 1.26 + 1.24 +
1.23 + 1.21 + 1.20
= 2048+ 1024 + 256 + 158 + 64 + 16 + 8 + 2 +
1
= (3547)10
2nd step
3547 16
384
221 16
27
61 1
1 1
(3547)10 = (CCA)16
2 16
(110111011011) = (CCA)
3. Convert into binary and display the answer in normalized
exponential form
247 1
123 1
61 1
30 1
15 1
7 1
3 1
1 1
0 1
(247) = (11110111)
10 2
= 0. 1111011 x 2
normalized exponential form
Question 3. Integer and Floating – point arithmetic?
20
1. Floating – point Addition
a. (0.1011 x 2 ) + (0.1001 x 2 )
5 5
= (0.1011 + 0. 1001) x 2 5
= 1.0100 x 25
= 0.10100 x 26
b. (0.1001 x 2 ) + (0.1110 x 2 )
3 5
= (0.001001 x 2 ) + (0.1110 x 25 )
5
= (0.001001 + 0.111000) x 25
= 1.000001 x 25
= 0.1000 x 26 (here have
truncation)
(0.1000001 x 26 )
2. Floating – point subtraction
a. (0.1110 x 2 ) – (0.1100 x 2 )
7 7
= 0.0010 x 2 7
= 0. 10 x 25
b. (0.1001 x 2 ) – ( 0.1000 x 2 )
8 5
= (0.1001 x 2 ) – ( 0.0001 x 28 )
8
= 0.1000 x 28
3. Floating – point multipl icat ion
a. (0.1010 x 2 ) x (0.1100 x 2 )
3 3
= (0.1010 x 0.1100) x 2 6
= 0.01111 x 26
= 0.1111 x 25
b. (0.11110 x 2 ) x ((0.01011) x 24 )
3
= (0.11110 x 0. 01011) x 2 7
= 0.001111 x 27
= 0.1111 x 25
4. Floating – point divis ion.
a. (0.11010 x 2 ) : (0.001 x 2 )
6 6
= (0.11010 x 26) : (1 x 23)
= 0.1101 x 26 : 1x 23
= 0.1101 x 23
b. (0.110111 x 2 ) : (0.1001 x 2 )
6 4
= (0.110111 : 0.1001) x 22
= (1101.11 : 1001) x 22
= 1.100001 x 22
= 0.1100001 x 23
Chapter 3: TYPES OF INSTRUCTION AND ADDRESSING.
Question 1. Types of instructions used in CS?
1. Arithmetic instruct ions.
Arithmetic instruct ions include direct ives to the computers to
perform addit ions, subtraction, multipl i cat ions, divis ions and
exponentiat ions.
2. Input/ output instruct ions.
They direct the computer to read data values from the
specif ied input devices into the main store for processing.
