Transcript 1.3 Modes of Operating System and User Interfaces

Types of Operating System
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Single user Single processor
Multiprogramming
Batch
Interactive
Multi access
Multi tasking
Time sharing
Real time
Multi Processing
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Single User Single Processor
• To allow the machine to be operated by only one
user at a time with at most one application
program loaded into main memory.
• DOS
Interactive:
• User interacts directly with the system to supply
commands.
• Data as the application program undergoes
execution and receives the results of processing.
• Direct to way communication
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Multi Programming
• Is defined as the apparent simultaneous
execution of two or more programs.
• When one job needs to wait for I/O, the
processor can switch to the other job
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Batch
• Several jobs are kept in
main memory at the same
time, and the CPU is
multiplexed among them.
• Processing is carried out
from beginning to end
without user interaction.
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Multi User OS
• Allows multiple users to use same
computers at same time.
• Examples
• Linux
• Unix
Multithreading OS
• That allow different parts of a program to
run concurrently
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Multi Processor OS
• That supports two or more processors that
running programs at the same time
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Time Sharing
• Using multiprogramming to handle multiple
interactive jobs
• Processor’s time is shared among multiple
users
• Multiple users simultaneously access the
system through terminals.
Multitasking OS
• That can execute more than one
processor at the same time.
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Real Time
• Often used as a control device in a
dedicated application such as controlling
scientific experiments, medical imaging
systems, industrial control systems, and
some display systems.
• Well-defined fixed-time constraints.
• Real-Time systems may be either hard or
soft real-time.
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Kinds
• Hard real-time:
– Secondary storage limited or absent, data stored in
short term memory, or read-only memory (ROM)
– Conflicts with time-sharing systems, not supported by
general-purpose operating systems.
• Soft real-time
– Limited utility in industrial control of robotics
– Useful in applications (multimedia, virtual reality)
requiring advanced operating-system features.
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Distributed computer systems
• Distribute the computation among several
physical processors.
• Loosely coupled system – each processor has
its own local memory; processors communicate
with one another through various
communications lines, such as high-speed
buses or telephone lines.
• Advantages of distributed systems.
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Resources Sharing
Computation speed up – load sharing
Reliability
Communications
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Client Server Systems
• In which cooperation and
intercommunication between the various
elements of a network is conducted.
• In a client server system, application
programs resides in server connected to
the LAN.
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User interfaces
• User interface is what you see when you turn on the
computer
• It consists of the cursors, prompts, icons and menus etc
• Which allow you to get something done using your
computer
• Ideally the user interface should be as easy to use as
possible
User interface may be
• Command driven interface
• Menu driven interface
• Graphical user interface
• Job control language
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Command driven interface
• With a command driven interface, you type in an
instruction, which is usually abbreviated, in order
to get something done.
• Are not easy to use
• A set of commands used to interact with
computer is called command language
• It requires exact spelling and punctuation
• Advantage:
• Commands for different software application are
rarely the same so user can be faster to use and
have learnt all the commands
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Menu driven interface
• The user enter data and
instruction by using menus
• Easy to use because the user
has not remember the syntax
of commands
• User can make a selection by
using either a mouse or a
keyboard
• Drop down list
• Present options
• Both Microsoft Windows and
Apple Macintosh programs are
menu driven
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Graphical User Interface (GUI)
• Is a visual environment that is used
by the user to communicate with
computer
• It uses windows ,icons, menus and
other graphical objects to issue
commands.
• Icons represent programs,
directories ,devices and files
• Advantage:
• Easy to use
• Easy to learn
• Attractive
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Disadvantages
• More immediate access store and
secondary store
• More powerful processor and graphical
card
• Slower then executing
• Greater no of operations is required
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Job control language interface
• A user has no direct interaction with the computer
system
• A user prepares the series of instructions off-line using a
JCL to describe the system
• Job control statement will specify
• Who owns the job
• Job priority
• Names of data file used
• Max lines to be printed
• Example:
• Line printer paper
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