An Operating Systems Vade Mecum

Historical development 9executing jobresident monitor and schedulerinterruptsdevice controlcard readerdisks printers tapesFigure 1.4 Spooling systemSpooling systems did not make efficient use of all of their resources. The job that wascurrently running might not need the entire main store. A job that performed transputwould idle the computer until the transput was finished. The next improvement was theintroduction of multiprogramming, a scheme in which more than one job is activesimultaneously. We show this situation in Figure 1.5. While one job is waiting for atransput operation to complete, another can compute. With luck, no time at all is wastedprocessesresponsesservice callsprocess interfacekerneldevice interfaceinterruptsdevice controlclockcardsdisksprinterstapesFigure 1.5 Batch multiprogramming