Soft real time is an achievable goal that can be

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Unformatted text preview: t 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 service. 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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