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| CPU-bound jobs: |
CPU-bound jobs. These jobs mostly perform numerical calculations, with little I/O operations. they are so called because they heavily utilize the CPU during the course of their processing programs used for scientific and engineering computations usually fall in this category of jobs.
2. I/O-bound jobs. These jobs perform very little computation and most of the time they perform I/O operations. Hence, their CPU utilization is very low. Programs used for commercial data processing applications usually fall in this category of jobs. in a uniprogramming system, the CPU will be idle whenever the job that is currently being processed by the system performs I/O operations. With CPU-bound jobs, The CPU idle time may not be significant, but for I/O-bound jobs, The CPU may be idle 80 to 90% of the time. Moreover, since I/O devices are slower than the CPU by 20,to 100 times, the CPU idle time is significant even for CPU-bound jobs that perform little I/O. The concept of multiprogramming was introduced to minimize the idle time of the CPU by organizing multiple jobs in the system so that the CPU always has something to execute. How this is done is explained below.