Unformatted text preview: ob was in
the form of punch cards, and at some later time the output was generated by the system—
user didn’t get to interact with his/her job. The output consisted of the result of the
program, as well as a dump of the final memory and register contents for debugging.
To speed up processing, operators batched together jobs with similar needs, and ran
them through the computer as a group. For example, all FORTRAN programs were
complied one after the other. The major task of such an operating system was to transfer
control automatically from one job to the next. In this execution environment, the CPU is
often idle because the speeds of the mechanical I/O devices such as a tape drive are
slower than that of electronic devices. Such systems in which the user does n get to
ot interact with his/her jobs and jobs with similar needs are executed in a “batch”, one after
the other, are known as batch systems . Digital Equipment Corporation’s VMS is an
example of a batch operating system.
Figure 2.1 shows the memory layout of a typical computer system, with the system
space containing operating system code and data currently in use and the user space
containing user programs (processes). In case of a batch system, the user space contains
one process at a time because only one process is executing at a given time. Figure 2.1 Memory partitioned into user and system spaces Multi-programmed Systems
Multi-programming increases CPU utilization by organizing jobs so that the CPU always
has one to ex...
View Full Document
This document was uploaded on 10/17/2012.
- Spring '12