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From: mac@ra.cs.Virginia.EDU (M. Alex Colvin)
Newsgroups: comp.realtime
Subject: Re: What is "real-time" really?
Summary: continuous approximation
Message-ID: <1027@ra.cs.Virginia.EDU>
Date: 1 Mar 90 23:49:57 GMT
References: <98692@linus.UUCP> <111040003@hpcvlx.cv.hp.com>
Organization: U.Va. CS Department, Charlottesville, VA
Lines: 13

real-time systems react to time, a continuous variable. because responses
take time, the response is approximate.

a characteristic of real-time systems is that they start with a quick
approximation, then iterate as time permits. at any time there is a useable
output. the more time available, the better.

there's probably a definition that uses the notion of continuity - for
every error epsilon, there's a time delta. maybe uniform continuity - for
every epsilon at any time, there's a constant time delta.

i agree that the best definition of "real-time" programs is programs that are
written with explicit attention to timing.