The document discusses different types of operating systems including timesharing, parallel, distributed, and personal computing operating systems. It provides details on timesharing systems, explaining their evolution and how they work using concepts like multiprocessing and multitasking. Round robin scheduling is also explained along with the advantages and disadvantages of timesharing. Examples of early timesharing systems like Dartmouth Time-Sharing System are given. Parallel and distributed systems are defined along with their applications. Finally, some popular personal computing operating systems like MS-DOS, Windows NT, 95, 98, XP, CE and Linux are briefly outlined.

2. ITS TYPES:
TIMESHARING
PARALLEL
DISTRIBUTED
&
PC OPERATING SYSTEMS

3. WHY TIMESHARING ?
EVOLUTION
MEANING
WORKING
RR SCHEDULING
COMPLEXITY
ADAVNTAGES AND
DISADVANTAGES

4. Less human-computer interaction
Single user was inefficient
Because early mainframes and
minicomputers were extremely
expensive

5.  The concept was first
described publicly in
early 1957 by Bob Bemer.
The first project to
implement a time-
sharing system was
initiated by John
McCarthy in late 1957
 The first commercially
successful time-sharing
system was the
Dartmouth Time-Sharing
System (DTSS) which was
first implemented at
Dartmouth College in
1964

6. Thomas Kurtz (left)
and John Kemeney

7.  Meaning of time
sharing: “sharing of
a computing
resource among
many users by
means of
multiprogramming
and multitasking”

8. ◦ Multiprogramming: ◦ Multitasking:
◦ more than one ◦ method by which
processor in close multiple tasks, share
communication, common processing
sharing computer resource such as CPU.
bus , clock and The CPU executes
memory and multiple tasks by
peripherals switching b/w them so
sometimes frequently that users
may interact each
program while it is
running.

9.  The user gives instructions to the OS or to a program
directly using mouse or keyboard and waits for
immediate results
 Uses CPU scheduling to select a job
 Programs queued for execution in FIFO order.
 Like multiprogramming, but timer device interrupts
after a quantum (time slice).
◦ Interrupted program is returned to end of FIFO
◦ Next program is taken from head of FIFO
 OS assigns some time slots to each job. Here, each
job is executed according to the allotted time slots.
Job1: 0 to 5
Job2: 5 to 10
Job3: 10 to 15

10.  Considerations influencing choice of time
quantum
◦ Shouldn’t be so large
◦ Shouldn’t be so small
Time quantum= 4 milliseconds
P1 P2 P3 P1 P1 P1 P1 P1
0 4 7 10 14 18 22 26 30

11.  Timesharing systems are more complex then
multiprogrammed OS that needs :
◦ Memory management and protection
◦ Virtual memory: process needs to be swapped in
and out of memory to disk in order to obtain a
reasonable time
◦ File systems: online file system is required for users
to access data and code
◦ Disk management: as file system resides on
collection of disks
◦ Sophisticated CPU scheduling schemes

12.  A time-sharing system (what we call a server nowdays) provides many many people the opportunity to use the
system. Technically, even a standard PC is a time-sharing system, because you can run many different programs
on it at a time (think Browser, iTunes, Anti-Virus, etc.).
The old mainframe systems had a card reader and an output. Only one set of cards could be run through at a
time. So, if payroll was running through all 14000 employee's paycheck calculations, you had to wait until they
were done. Modern mainframe systems have some time-sharing capabilities by allowing multiple processes to
run on the system, but those processes are virtualized, rather than a true sharing system. However, the details
of that can be left to others.
There are benefits and downsides to every type of system. In a mainframe-style system, all resources are
available to the process being run, which benefits large data crunching operations (like payroll). The downside to
a mainframe-style system is that only one process can run at a time in each virtual machine.
In a server-style system, all resources are shared among all processes. If a process "runs away" by using more
processes than it should, then the other processes suffer, which the end-user sees as a server responding very
slowly and/or "timing out". The upside to a server-style system is that you can serve web pages to thousands of
people, while at the same time handling thousands of pieces of email.
If you go for a little bit of luxury and the convenience for your vacation, then, timeshares might be the one
you're looking for. But if you're on a tight budget, this may not be for you especially with our crisis-stricken
economy. The number one disadvantage of this is the cost involve like the maintenance fees.
in short

13. Advantages are :
◦ CPU efficiency.
◦ each user gets CPU time.
Disadvantage :
◦ complex OS required.
◦ since all output devices are centralized on a single
PC therefore there will be time delay from one
person to another.

14. Contents:
Its meaning
working
Types
Application and scope

15.  Also known as
multiprocessor CPU CPU CPU
systems
 More than one
processor, sharing
–computer buses,
clock, memory and MEMORY
peripherals.

16. Principle behind it
◦ Large problems can often be divided into smaller
ones, which are then solved concurrently
◦ A parallel system works by dividing the set of
calculations into smaller parts and distributing
them b/w the machines on a network
How do the communication takes place?
◦ Shared memory
◦ Distributed memory

17.  Using a single processor become limiting
factor in applications like:
◦ weather forecasting, simulation, image processing,
statistical data analysis
 How the problem was tackled?
◦ Dividing it into modules
◦ Combining with network based service resulting in
distributed computing

18. Asymmetric multiprocessing
◦ Each processor is assigned a specific task;
◦ Master processor schedules and allocated work to slave
processors
◦ More common in extremely large systems
Symmetric multiprocessing (SMP)
◦ Each processor runs and identical copy of the operating
system
◦ Many processes can run at once without performance
deterioration
◦ Most modern operating systems support SMP

21.  Increased throughput: as there are no. of
processors are increased
 Economy of sale: save money as they can
share peripherals, mass storage and power
supplies
 Increased reliability: failure of one processor
will not halt the entire system but only slows
it
 graceful degradation
 fail-soft systems

24. Distribute computation among many
processors.
Loosely coupled -no shared memory,
various communication lines ,each
processor has its own local memory;
processors communicate with one
another through various
communications lines, such as high
speed buses or telephone lines
client/server architectures

25. SITE A SITE B
server
networ resources
k
communication
client
SITE C

27.  Resources Computation speed up – load
sharing
 Reliability
 Communications
 Sharing

28.  Requires networking infrastructure
 Local area networks (LAN) or Wide area
networks (WAN)
 May be either client-server or peer-to-peer
systems

29. client client client client
networ
k
server

30.  Benefits:  Apps:
◦ resource sharing
◦ digital libraries, digital
◦ computation speed- multimedia
up
◦ reliability
◦ communication -e.g.
email

31. • Single user systems, portable.
• I/O devices -keyboards, mice,
display screens, small printers.
• Laptops and palmtops, Smart
cards, Wireless devices.
• Single user systems may not need
advanced CPU utilization or
protection features.
• Advantages: user convenience,
responsiveness, ubiquitous

32.  Older Operating System
◦ MS-DOS
◦ Microsoft Windows like:-
◦ Window NT
◦ Window 95
◦ Window 98
 Common Operating System
◦ Window XP
◦ Window ME
◦ Window CE
◦ Linux

33.  The operating system of a computer performs
basic tasks such as: recognizing information from
the keyboard and mouse, sending information to
the monitor, storing of information to the hard
drive, and controlling device peripherals as printers
and flatbed scanners.
Operating systems provide the basis for running
common applications such as word processors and
Internet browsers. Operating systems are also
responsible for running Assistive Technology
applications such as screen magnifiers, and
applications that read text aloud.

34.  MS-DOS
 Window NT
 Window 95
 Window 98

35. Command-line interface
Prompt – system is waiting for you to
do something
Single user single-tasking OS
Command line interface
16-bit OS, powerful, fast

36.  Strong security
 Versions
◦ NT Workstation
◦ NT Server
 Drawbacks
◦ Lacks support for older Windows and MS-DOS
software and hardware
◦ Complex to learn and use
◦ Requires more memory and processing power

37. Self-contained OS
DOS commands still
available
Start programs by
Start button
Double clicking the icon
Long file names up to
255 characters

38. XP means eXperience
-Desktop computer
 2 versions
 Professional Client
 Personal Client
New and updated features
 Start Menu and Taskbar improvements
 Faster start-up,
 Fast user switching

39. Multimedia support -- Windows Media Player 7
 Jukebox
◦ Record music CDs as digital files
 Windows Movie Maker
◦ Basic video editing
 Windows Image Acquisition
◦ Scanner and digital camera
 Reliability Features
◦ System File Protection
◦ Auto Update
◦ System Restore

40. Where used
 Embedded systems
◦ Industrial controllers
◦ Robots
◦ Office equipment
◦ Cameras
◦ Telephones
◦ Home entertainment devices
 Pocket PC
 Internet appliance market
Subset of Windows
 Less memory
 Smaller screens
 Little or no file storage
 Provides Internet connectivity

41.  LINUX-like OS
 Open-source software
◦ Download it free
◦ Make changes
◦ Restriction – any changes must be freely available to the
public
 PC Setup
◦ PC comes with Windows installed
◦ Install LINUX in a dual-boot configuration
 Advantages over Windows
◦ Extremely stable
◦ Internet support
◦ Reinstallation is simpler
 Disadvantage
◦ Scarcity of applications

42. Operating system Features Examples
Timesharing Simultaneous user Multics file system
interaction, on-line (1965), Unix (1974)
file systems
Parallel Hierarchical systems, RC 4000 system
extensible kernels, (1969), 13 Venus
parallel programming system (1972),
concepts, secure 14 Boss 2 system
parallel languages (1975),
Personal computing Graphic user interface OS 6 (1972),
Pilot system (1980)
Distributed Remote servers VFS file server (1979),
Unix united RPC
(1982),
Amoeba system (1992)

43. Queries????