Operating System and operation modules

• A computer system can be designed to operate in different modes in terms of number of users working on the machine at the same time, number of processors used, data handling and the number of applications running simultaneously on the same computer system.

• A computer system needs to be configured accordingly and the system will also need the operating system which can support such operations.

• in batch processing the processing transactions(交易) are executed in a group or batches. No user interaction(相互影响) is required one batch processing in underway.

• the next batch is taken for processing only after the first batch is completed this often lead to CPU processing time is not optimally utilized

• Example : IMB : OS2

• Multi tasking allows more than one program to run concurrently.
• the tasks share common processing resources, such as a CPU time and main memory.

• in multi tasking process, only one CPU is involved but it switches from one program to another so quickly that it gives an illusion of executing all the programs at the same time.

• the multi processor processing makes use of more than one processor in a same system to enhance the system performance. Due to number of processor the system performance is significantly improved. however, all the processes share the same common main memory(RAM)

• A computer system with multi processor needs operating system which can support multiple programs execution simultaneously

• A real-time operating system(RTOS commonly pronounced as “are-toss”) is a multitasking operating system designed for real-time applications. Such applications include embedded systems, industrial robots, scientific research equipment and others.

• A real-time computing guarantees response within specific time limits and thus suitable for quick reaction system.

• Hard Real-time operating systems
  • Meets deadlines with zero degree of flexibility
  • Missed deadlines cause catastrophe(灾难)
  • Cost of catastrophe is high
• Soft Real-time operating system
  • Meets deadlines with some degree of flexibility
  • Missed deadlines does not cause catastrophe
  • cost rise in proportion of the delay
• the real-time systems are sued in the situations where a large number of events(generally external to the computer system) are required to be accepted and processed in the form of quick response. such systems should be a multitasking system.

• Almost all the modern telecommunication systems make use of RTOS

• Radar systems, network switching control system, satellite monitoring system, satellite launch-control and manoeuvring(手段) mechanisms, global positioning system all have their operational dependence on RTOS

• Now a days RTOS is increasingly finding use in strategic and military operations. there are used in guided missile launching units, track-and-trace spy satellite

• Multi user operating system is a computer operating system(OS) that allows multi users to access a single system with one OS managing the computer system.

• Each user is given a separate login credentials and more than one user can simultaneously use the computer system. each user will have their own settings.