computer operations(2) (5th copy)

8/8/2019 Computer Operations(2) (5th Copy)

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OBJECTIVESAt the end of this lecture you should be able to:understand basic organization of computer

systemunderstand the five major operations of

computers (Input, Output Central Processing Unitand Backing store. differentiate between

primary memory and secondary memory

differentiate between primary storage andsecondary storage units


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OBJECTIVES (cont)differentiate between primary

memory and secondary memory.differentiate between primarystorage and secondary storage units


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D ata is generally organized in a

hierarchy that begins with the smallestpiece and progresses to the highest

part called the database.


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BITA binary digit (1 or 0) is called a bit.

The smallest unit of data is the bit whichrepresent either an on/off (0/1) circuit. A Bit

represents the actual physical storage state of data on storage media. It is the storage unit of

the computer hardware itself.


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BYTE

A Byte is a basic grouping of bits.A group of byte is called a character.

8 bits make up one byte.Characters represent the basic building blocks of information. i.e. from

the user s point of view, character is the most basic element of data thatcan be observed and manipulated.

Eg; numbers (1,2,3,4,5,6, ..) letters (a,b,c,d, ..) or symbols (+,-,*..).


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FIELD

A Field is a combination of characters thatdescribes an aspect of an object or activity.

Fields are also called attributes that is eithercharacteristics or qualities of entities (anobject, a person, or a place etc) an object

name, employee salary etc. the specific valueof an attribute is known as D ata item.


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RECORDA record is a collection of related fields, i.e. A collection of different aspect of an object activity to achieve a morecomplex description.Using an employee record as an example, a record of fields about one (single) employee.Such record will have different fields (name, address, phonenumber, pay rate).


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FILE

A collection of related records for an object is called a file.In a program, employee record=a collection of all

employee records within the company.An inventory file is a collection of all inventory records fora particular company.


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D ATABASE

A collection of integrated and related files are called a

database.A database is organized information designed to meet the

needs of a particular business environment. A database canbe manually stored in cabinets but this greatly reduces thesafety and accuracy of information. A better management

procedure is to automate the storage of large size databaseto reduce data inconsistency, data isolation replacement, andno-of security problems amount the num-of records or files

which determine storage size.


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PATH THROUGH WHICHD ATA ISPROCESSED


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D iskBACKING STORE

MEMORYIMMED IATE ACCESS

STORE

CONTROL UNIT/

REGISTER

ARITHMETICUNIT (ALU)

INPUT UNIT

OUTPUT

UNIT


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(A) INPUT UNIT:

reads information to be stored in amachine and convert it to a form that

can later be used.


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the process of entering data and

programs in to the computersystem.

Therefore, the input unit takes datafrom us to the computer in anorganized manner for processing.

reads information to be stored in amachine and convert it to a form thatcan later be used.


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(B) Processing unit (CPU):

this unit consists of the control unit, registers,immediate Access store, Arithmetic unit and

Backing store i.e. H DD& MM.


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(B.1) Control unit: all functions arecoordinated by this unit.This integrates and comes out

instructions contained in a program.

Registers: small stores for holding data

temporary hold data to be used in a calculationand queue it up upon request.


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(B.2) Immediate Access Store:(main memory) very fast access store

which provides the amount of spaceneeded for computing activity.


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(B.3) ARITHMETIC UNIT:

is the actual generational unit wherecalculations are formed and where LOGICAL

processes of selecting, sorting and comparing of information take place.


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(C) Storage/Backing store:

data can be permanently stored in the form

of reading and magnetic material.


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The process of saving data and

instructions permanently isknown as storage.


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D ata has to be fed into the

system before the actualprocessing starts. It is because

the processing speed of CentralProcessing Unit (CPU) is so fastthat the data has to be provided

to CPU with the same speed.


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Therefore the data is first storedin the storage unit for faster

access and processing.


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This storage unit or the primarystorage of the computer system

is designed to do the abovefunctionality. It provides spacefor storing data and instructions.


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FUNCTIONS1. All data and instructions are

stored before and afterprocessing.2. Intermediate results of processing are also stored.


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(D ) Output unit:

it presents the results of a computer operationas on TV screen or print on a tape, disk or card.


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MEMORY SYSTEM IN ACOMPUTER


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There are two kinds of computermemory: primary and secondary .

Primary memory is accessibledirectly by the processing unit.


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RAM is an example of primary

memory. As soon as thecomputer is switched off thecontents of the primary memory

is lost. You can store and retrievedata much faster with primary

memory compared to secondarymemory.


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Secondary memory such asfloppy disks, magnetic disk, etc.,is located outside the computer

(ROM).


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Primary memory is moreexpensive than secondary

memory. Because of this the sizeof primary memory is less than

that of secondary memory.


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Computer memory is used tostore two things: i) instructions

to execute a program and ii)data.


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When the computer is doing any

job, the data that have to beprocessed are stored in the

primary memory. This data maycome from an input device likekeyboard or from a secondary

storage device like a floppy disk.


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SUMMARY


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D ata in specially prepared form called acode is fed through the input unit and isread by its reading device turned in to

electrical pulses and sent into the controlunit.

Since computers do not have brains, information

is fed into a computer in a particular manner.


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This can be a number or lettercode represented by electrical

pulses.

These pulses are recorded and transferred data

into the storage unit.


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we discussed five basicoperations that a computerperforms. These are input,

storage, processing, output andcontrol.


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A computer accepts data asinput, stores it, processes it as

the user requires and providesthe output in a desired format.


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The storage unit of a computer isdivided into two parts: primarystorage and secondary storage.

We have discussed the devicesused for these two types of

storage and their usefulness.


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A computer performs basicallyfive major operations orfunctions irrespective of theirsize and make


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These are :

1) it accepts data or instructionsby way of input,2) it stores data,

3) it can process data as requiredby the user,

4) it gives results in the form of output, and5) it controls all operations inside

a com uter.


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ENJOY YOUR STUD IES

computer operations(2) (5th copy)

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