Question

what are the characteristics of single user operating system in points

Answer 1

Single user operating is that in which one user works on one interface. In these systems no other operating system is interrupting with the processing. Single user ..

Answer 2

Process

The fundamental notion of multi-tasking operating systems is the process. the program concept is not enough. Nothing prevents the same program is executed several times simultaneously: one may want, for example, two windows emacs or two gv windows to compare texts.

A process is a program instance being run.

A process is represented by a program (the code), but also its data and by parameters indicating where it is, allowing it to continue if it is interrupted (execution stack, program counter ...). We talk about the program environment.

A process is also called task in the case of Linux.

Timeshare

Most multi-tasking operating systems are implemented on a computer having a single microprocessor. This one, at a given moment, really runs one program, but the system can do switch from one program to another by running each program for several tens of milliseconds; This gives users the impression all programs are executed simultaneously. This is called system timeshare.

Some call pseudo-parallel this very rapid switching of a processor program to another, to differentiate it from true parallelism that occurs at the equipment when the processor works in conjunction with some of input-output devices.