[ale] Linux job

[Jeff Hubbs]

Rev. Johnny Healey wrote:

> I thought UNIX and Windows were considered time-sharing.  They allow 
> multiple users/services to use the system at the same time, but don't 
> offer the same performance guarantees that a RTOS provides.

You're close.  "Time sharing" is a legacy term that refers to the idea 
of multiple users running processes on the same computer at the same 
time with no real sense of the other users' presence.  This was an 
important conceptual leap from one computer per team of people all 
working on the same task.  The term has fallen into disuse but is closer 
in concept to "cooperative multitasking" in which the processes must 
relinquish control without the use of a master scheduling mechanism.

UNIX, WinNT and derivatives, VMS, and Linux are all "pre-emptive 
multitasking;" the operating system handles the scheduling.  Novell 
Netware, old MacOS, and old Windows were CM OSses.  See 
http://en.wikipedia.org/wiki/Computer_multitasking.

Jeff