The services operating systems provide include:
?—? Management of I/O
?—? Management of memory
?—? Scheduling of user processes (start, interrupt, and stop)
?—? A secure and reliable environment for programs and users
96 OPERATING SYSTEMS [CHAP. 6
?—? A convenient interface for users
?—? Networking services
?—? Messaging and synchronization services between processes
?—? Utility ???system software??? such as editors, loaders, help, etc.
OPERATING SYSTEMS HISTORY
Batch Jobs
Early conceptions of computing revolved around computing ???jobs.??? A computational job would be presented
to the computer, the computer would process the job, and the computer would deliver an answer. The first operating
systems made this sort of use easier, and were known as ???batch??? operating systems (1955??“1965).
A ???resident monitor??? (the operating system) provided the commonly needed routines to perform I/O to the
devices of the day (most of the OS code consisted of device drivers), and to format data back and forth between
encoded form and binary values. The resident monitor also provided a simpler user interface through job
control language (JCL).
The user would embed JCL commands to the operating system in the sequence of program instructions and
data presented to the computer as a ???batch job.
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