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real time is an achievable goal that can be mixed with other types of systems, whereas
hard real time systems conflict with the operation of other systems such as time-sharing
systems, and the two cannot be mixed. Interrupts, traps and software interrupts
An interrupt is a signal generated by a hardware device (usually an I/O device) to get
CPU’s attention. Interrupt transfers control to the interrupt service routine (ISR),
generally through the interrupt vector table , which contains the addresses of all the
service routines. The interrupt service routine executes; on completio n the CPU resumes
the interrupted computation. Interrupt architecture must save the address of the
interrupted instruction. Incoming interrupts are disabled while another interrupt is being
processed to prevent a lost interrupt . An operating system is an interrupt driven software.
A trap (or an exception) is a software-generated interrupt caused either by an error
(division by zero or invalid memory access) or by a user request for an operating system
A signal is an event generated to get attention of a process. An example of a signal is
the event that is generated when you run a program and then press <Ctrl-C>. The
signal generated in this case is called SIGINT (Interrupt signal). Three actions are
possible on a signal:
1. Kernel-defined default actio n—which usually results in process termination and,
in some cases, generation of a ‘core’ file that can be used the programmer/user to
know the state of the process at the time of its...
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- Spring '12