Next: Multiprogramming with variable partitions
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Consider the warehouse example again, multiple jobs of different types (perhaps size)
entering storage in different partitions
- Several users simultaneously compete for system resources
- switch between I/O jobs and calculation jobs for instance
- To take advantage of this sharing of CPU, important for many jobs to be present
in main memory
- Allowing Relocation and Transfers between partitions
- Protection implemented by the use of several boundary registers
: low and high boundary registers, or base register with length
- Fragmentation occurs if user programs cannot completely fill a partition -
wasteful.
![figure56](img2.gif)
Figure 2: Multiprogramming - fixed partitions
Omer F Rana
Tue Feb 11 19:21:10 GMT 1997