1. Types of Operating Systems V1.0 (22/10/2005)

2. Classification in earlier days Computer was very expensive and not user friendly. To minimize idle time, computer are accordingly classified as  Batch processing system  Multi-user system  Real-time system

3. Batch processing system Computers were relatively expensive, when programmers finish programming, they have to record the instructions on pins cards, hand it to computer operators, and computer operators will run the cards in a batch Modern systems will collect similar programs & processes, then schedule to process All programs and processes are run according to assigned priority For any data input, must be done before processing During program and processes execution, interruption is prohibited NOT real-time and interactive Simpler system design When teachers mark assignment, do them in a batch will be more effective

4. Multi-user system Process requests from different users at the same time Share resources at the same time Using time sharing technology, let users work with less waiting time Divide jobs into small fragments to maximize processing time for each user. When time is up, suspend the resources and free up resources for other users. One after one and skip those inactive processes Like waiters, when called by different customers, need to take care of them in turn to minimize customer waiting time

5. Real-time system Designed for Time critical jobs, like pilot system, flight booking system and automatic system Avoid error due to time delay External interruption at any time of processing Instant response to input Like Students doing experiments, when there is danger, teachers could respond instantly

6. Other common types Single-user system Multiprogramming system Multitasking system Network system Online interactive system

7. Single-user system With emergence of Personal computers and network is not popular, multi-user is not catered Resources solely allocated Simpler system design Design is based on interactivity, thus CPU often idle at I/O operations, waste valuable computation power

8. Multiprogramming system As I/O transfer rate is slower than CPU, CPU is idle during I/O activities During execution, CPU idle time is up to 80% System executes other programs during CPU idle time CPU seem to run multiple programs at the same time With System scheduling, switching between processes is possible System must know processing status, register records and corresponding resource allocation of each running program

9. Multitasking system Multitasking system may process same program / program fragment at the same time Run multiple processes at the same time, those processes can come from different programs Minimize wasting resources by avoid running duplicate processes at the same time Share resources when running duplicate processes at the same time

10. Network system No difference from Single User System More network and system utilities Make network attached system/devices receive service requests  Block and forward requests from application software  Deliver jobs to appropriate network / server service Network communication and data transfer features Manage network resources among computers Aid servers provide  Its own resources  Rights to control network resources How many users are permitted to use the resource simultaneously  Storage and Network management  User / Groups management  User login authentication  User permissions Eligible to read/write ? Any quota limit?

11. Online interactive system User can input data at real-time System response promptly a.k.a Network system Like online games and video conferencing