Multiprocessing

In multiprocessing systems, two or more CPUs are connected together. Therefore it is possible to execute instructions from different programs at the same time. Thus more than one instruction can be executed simultaneously. The idle time of the computer reduces, since there is not user intervention in between jobs.

The disadvantages of batch processing are:

· The data has to be first accumulated and then processed. Therefore there is a possibility of delay in execution of jobs,

· It is not possible to change priority of jobs. If both jobs have the same priority, one of them has to wait in the batch till the complete execution of the other.

Execute different instructions of the same program. Different multiprocessing systems use different types of memory configurations. Some systems have a Common main memory for all the CPUs, in some systems each system has its own main memory while in still others each CPU can have its own memory as well as share a common memory with other processors.

Multiprocessing systems require a very complex and sophisticated operating system to coordinate all the activities of the multiple CPUs and other devices. Multiprocessing systems are also very expensive.