Path: utzoo!mnetor!uunet!mcvax!enea!sommar
From: sommar@enea.se (Erland Sommarskog)
Newsgroups: comp.software-eng
Subject: Re: H/W vs. S/W
Message-ID: <2885@enea.se>
Date: 20 Mar 88 16:52:48 GMT
Reply-To: sommar@enea.UUCP(Erland Sommarskog)
Followup-To: comp.software-eng
Organization: ENEA DATA AB, Sweden
Lines: 30


Several have mentioned in this discussion that it's rather cycle time
which decides thorough you are before testing. I can't but agree. And
to toss in my two cents, I'd like to tell about my experience from a
project which contained both software and hardware development. (I
was on the software side.)

In this project they didn't use custom design, but just simple PALs.
I would say there was no difference between the frequency of errors.
We were both as bad. (And when an error was revealed, we always
blamed the other side for it, of course.) You should have seen the
first prototypes of boards. Full of loose threads, circuits upside
down and I don't know what. But also newer CADs got threads after a while.
  Also, the speed of the first prototypes was slower than the one of 
the software. 

Someone in the Soft-Eng Digest said that when you stripped away
microprograms and such, the hardware had very less complexity than
the software. I have to object here. May be the logic is simpler, but
other factors, unknown to software people, do appear. They have
to take physical factors in regard. Disturbances, race conditions,
variation in components, influence of temperature and so forth.
And when you have tested a program, you have tested it. This is not
true for a hardware board. You have to test every single instance
to check for bad solderings, circuits etc.
-- 
Erland Sommarskog       
ENEA Data, Stockholm        
sommar@enea.UUCP           "Si tu crois l'amour tabou...
                            Regarde bien, les yeux d'un fou!!!" -- Ange