Path: utzoo!mnetor!uunet!lll-winken!lll-tis!oodis01!uplherc!esunix!sedwards
From: sedwards@esunix.UUCP (Scott Edwards)
Newsgroups: comp.arch
Subject: Re: RISC != real-time control
Message-ID: <825@esunix.UUCP>
Date: 4 May 88 22:03:05 GMT
References: <1534@pt.cs.cmu.edu>
Organization: Evans & Sutherland, Salt Lake City, Utah
Lines: 18

From article <1534@pt.cs.cmu.edu>, by schmitz@FAS.RI.CMU.EDU (Donald Schmitz):
> In article <1521@pt.cs.cmu.edu> koopman@A.GP.CS.CMU.EDU (Philip Koopman) writes:
> 
>>Real-time control programs often have a situation where only
>>X microseconds are available to perform a task.  .....
> 
> This may be straying somewhat from the original point, but what sort of
> applications really have such exact timing deadlines?  I have done a little
> real-time motion control, ....

I worked on a project a while back that implimented a motion control servo
loop with a microprocessor and every time the uP didn't make the deadline
the loop would go unstable and lost all control.

It was fun to watch!   We finally had to change the time period so that the
processor always completed it's job on time, even tho in other modes it
was idle 60% of the time.

-- Scott