From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.5-pre1 (2020-06-20) on ip-172-31-74-118.ec2.internal X-Spam-Level: X-Spam-Status: No, score=-1.9 required=3.0 tests=BAYES_00 autolearn=ham autolearn_force=no version=3.4.5-pre1 Date: 18 Oct 92 14:28:03 GMT From: cis.ohio-state.edu!magnus.acs.ohio-state.edu!usenet.ins.cwru.edu!agate!do c.ic.ac.uk!uknet!mcsun!sunic!kth.se!admin.kth.se!nobeltech!dawe@ucbvax.Berkeley .EDU (Daniel Wengelin) Subject: Re: What is "real-time"? Message-ID: <1992Oct18.142803.4807@nobeltech.se> List-Id: In article <1992Oct16.213820.28793@col.hp.com> tbc@col.hp.com (Tim Chambers) wr ites: >First I'll explain the approach which is used in our organization. Rather >than define "real-time" software, we break it into two categories: >"time-sensitive" and "time-critical." Time-sensitive software is that for It somehow appears as if "time-sensitive" is rather irrelevant. I cannot remember that I've ever seen a program that is not "time-sensitive" according to the proposed definition. And if all programs are "time- sensitive", and some programs are also "time-critical", then this distinction is of little use. I agree on the definition on the theme "a real-time task is a task whose correctness rely on time constraints". I also find it probable that most systems is a mix of real-time and other tasks. The distinction between "hard" and "soft" real-time is obscure to me. I see two different explainations. 1) "Hard" real-time has fixed deadlines while "soft" has statistical time constraints. 2) "Hard" real-time systems are bought by someone that considers the proof of rate-monotonic scheduling as magic ;) , and wants to see the scheduling of tasks in a timing diagram, while "soft" real-time systems are ordered by a customer that is satisfied if the system meets its deadlines, no matter when in the allowed time-frame an individual task executes. The latter explaination puts the classification of "hard" or "soft" in the eye of the beholder (customer) rather than in the system itself. Daniel W. -- The above is my personal opinion ----------------------------------------------------------------------- -- -- -- Daniel Wengelin -- -- NobelTech AB (Winner of the -92 Ada Industry Leadership Award) -- -- Naval Systems Division -- -----------------------------------------------------------------------