Lecture 2
Software continued:-
System Software:-
1.
Operating system :-Dos, Windows XP, NT, 7, 8 ,vista,
Novel Netware, Novel Netware.
Categorization based on
a)
No of task we can run at one time. Single or
multiple
b)
No of Users accessing this. Single or multiple.
Single user Multiple task OS. Ex:- Windows various versions.
Single user Single task. Ex:- DOS
Multiuser single task. This is not practical since we cannot expect
multiple users to use the same task.
Multiuser Multitask. Ex:- Linux ( open source, services are
charged. The name is abrogated as Linux is not UNIX), Novel Netware. To have
this kind there need to be a server and client configuration. Ex:- Internet usage.
Railway ticketing, LAN.
UNIX is not an Operating system.
It is a specification based on which there is Operating system is built (this
was developed by Bell laboratory). We need to say, the operating system is of UNIX
type. Each company has their brand name (IBM Aix, HP UX, and Sun Solaris).
Only the operating system which
defines the utility based on the above discussion.
Features of Operating systems:-
a)
Act as user interface
b)
Process management. Start, kill and scheduling
of a process. Sequencing of the processes.
c)
Memory management (Primary memory RAM). Memory allocation,
de-allocation cleaning, isolation. When the memory gets full then it takes a
snap short of the fist process and puts it on the Hard disk and executes it
once it gets free.
d)
Input / Output Management. Printer, Keyboard,
saving of information on word, PPT, error management.
e)
Security. Isolation of data based on login by
user etc.
f)
File management.
g)
Added utilities as part of OS, like calendar , browser
, Remote desktop connectivity.
2.
Database management system:- This is also a
system software.
A)
Oracle
B)
Sybase
C)
SQL
D)
MS Access
E)
FoxPro
F)
MySQL Open source DBMS
There are 2 parts to it . Management system where you
provide rules like read, write , access and permissions . Data base stores all
the data in its own way , but will give you the data the same way you want to
see it.
Advantages:-
a)
Volume of data stored.
b)
Fine grained security.
c)
Multiple access with proper control.
d)
Monitoring facility of usage.
e)
Auto recovery , auto saving .
f)
High reliability.
g)
Faster transactions.
h)
Data independence. Irrespective of how the data
is stored . we can fetch the data in any format user wants.
Based on the way data is sorted( storage model) in the data base management system.
a)
Hierarchal
b)
Networked
c)
Relational RDBMS ( Oracle, SyBase , Foxpro,
MsAccess). Data is stored in a table format with various attributes in column
with the name of the employee in Rows. All tables are related using common
columns.
Columns which can uniquely
identify the data in the table is called Primary key. Foreign key is a primary key
of one table which appears in another table.
d)
Object oriented
User either directly access the database or through
Applications. Each manufacturer makes this DBMS with their own language of
interaction. Users need to get training to use it. Every time I use different
DBMS they need to get training to use it.
Finally ANSI :- American National standard Institute. Brought
about a common language to solve the above problem and SQL was formed.
TWO basic requirements for SQL: - All DBMS should be able
to use it. And users need to be able to use it easily.
SQL:- Structured Query Language. It is not a DBMS. It is
only to be used with RDBMS. Statement of command based language.
a)
Data manipulation language. DML ( commands like
Insert into table employee, record, Delete , Update , Select to retrieve data
from DBMS )
b)
Data definition Language. DDL (Data Definition
like Create table, Alter Table , Drop table to delete it.
c)
Data control Language. DCL (controlling access
to the information. Define controls like Grant R, RW , W , Revoke to stop
access previously given to a user).
Next class will be on computer networks.
