1. Types of OS Operating Systems are of different types Mainframe OS
Server OS
Multiprocessor OS
Personal Computer OS
Real Time OS
Embedded OS
Smart Card OS

2. Mainframe OS
Room sized Computers still found today also in major corporate data centers.
I/O Capacity is large (1000 disks and thousands of gigabytes of data)
High-end web servers, Large Scale E-comm sites, Servers for business-to-business transactions
Mainframe Os’s are heavily oriented towards processing many Jobs at once, needs prodigious amount of I/O.
Typically offers 3 kinds of services:
Batch processing (No user Interaction)
Routine Jobs like claims processing in LICs or Sales reporting for a chain of Jobs.
Transaction Processing (small requests, but system must handle thousands per second)
Check Processing or Airline Reservation or any Reservation System.
Time-Sharing (multiple users)
Querying a big databases.
Mainframe OS is OS/390 a descendant of OS/360.

3. Server OS
They Typically run on Servers (Large PCs, Workstations, Mainframes)
Serves multiple users over a network
Allows users to share H/W and S/W resources
Servers provide print service, file service or web services.
Internet providers use servers to support customers & web sites to store web pages & handle incoming requests.
, Groupware & messaging
Terminal Services
Caching (usually Internet by storing previous files)
Typical server OSs are Novell Server, Win NT, UNIX, Win 2000, Linux.

4. Server OS

5. Multiprocessor OS
To get major computer power is to connect multiple CPUs in single system
Depending on connection and what is shared, these are Parallel Computers, Multicomputers or multiprocessors
Special OS, Variation of Serve OS with connectivity & communication features.
When number of users increases the response time has to be kept more.
When the volume of data to be processed like
Weather forecasting
Terrain mapping
Nuclear Research
Image Processing
Simulations
Just one processor did not suffice the purpose.

6. Multiprocessor OS
Speed of computer has to be enhanced by adding more processors.
Two major multiprocessor and Parallel systems
Advantages:
To increase Throughput
By increasing number of processors, major work can be done in shorter period of time.
Can save money compare to multiple single systems.
By sharing peripherals, cabinets, Power Supplies etc.
If several programs are to operate on the same set of data then cheaper to store on one disk instead of diff disks and diff processors share them (instead of several computers)
They increases reliability
Failure of one processor will not halt the system, instead work of failed processor can be distributed among other processors.
SUN OS version 4 & version 5.

7. Personal Computer OS
Job is to provide good interface to a single user.
Widely used for word processing, spreadsheets, Internet Access etc.
Day-to-Day work
Win 98, win 2000, Mac OS, Linux

8. Real Time OS
These Systems are characterized by having time as a key parameter. (Special Purpose OS)
Often used as a control device in a dedicated application
Control Scientific Experiments
Medical Imaging Systems
Industrial Control Systems
Home Appliances Systems
Weapon Systems
Security Alarm Systems etc.
Has well defined, fixed time constraints, processing must be done within defined constraints or the system will fail.
It is said to work properly if it returns results within the time limits.
In time-sharing it is desired to respond quickly not mandatory here it is mandatory.
Two types Hard Real Time OS and Soft Real Time OS

9. Real Time OS Cont… Hard Real Time OS Soft Real Time OS
System Guarantees that critical task completes on time.
All delays in the system must be bounded
Ex. Missile Launching (Missile has to leave the earth within the specified time limit if not, then it will crash on the earth).
Car manufacturing
Security Alarms
Chemical Plants
Medical Systems
Soft Real Time OS
In this type of OS missing an occasional deadline is acceptable. Ex
Online Databases,
Online Audio,
Multimedia Systems,
Virtual Reality.

10. Embedded OS
With the use of small & small Computers we come to palmtop computers and embedded systems.
Palmtop or PDA fits in a pockets and performs many functions like electronic address book and memo pad.
These operating systems are designed to be very compact and efficient, forsaking many functions
include the software used in
Automated Teller Machines,
Cash Registers,
CCTV systems,
TV box set,GPS,
jukeboxes, Microwave Ovens, Mobile Phones, etc.
They Often have some characteristics of Real Time OS also but size, memory & power is restricted
Palm OS, Windows CE

11. ICI's Improved Data Modem (IDM)
Telica's Plexus 9000 Multiservice Access Switch
Xerox Document Centre
Scio Systems and LynxOS put the U.S. Mail in its Place

12. Smart Card OS The smallest OS run on smart cards.
Credit Card size devices containing CPU chips
provide a standardized exchange of information to implement authentication, verification, secure storage, encryption and decryption etc.
Some can handle only Electronic payments.
Other handles multiple functions
JavaCard OS
MULTOS (Multi-application Operating System).
Microsoft is on the smart card highway with Smart Card for Windows.

13. Smart Card OS
IIT Kanpur, along with National Informatics Centre (NIC) and a sub-committee of SCAFI piloted an effort to standardize Operating System that could be used for Indian Governmental applications.
This standard, known as SCSOTA (Smart Card Operating System for Transport Application)
was originally designed for Driving License and Vehicle Registration and is currently accepted as an OS for all Governmental application.