From: <(>
Date: Thu Sep 9 15:58:51 1999

> I found myself in the mood for revisiting the macabre side of
>classic computing and decided to search for Therac stuff. See:
> Now it seems to me that the fellow who wrote this article was
>pretty full of it. If you can get past his overuse of passive voice and
>continual nominalization, you may note that many of his points are far too
>theoretical and not supported by direct observation, knowledge, etc.

It's clear (to me, at least) that he's never directly worked with
any of the Therac machines, nor did he even bother talking to the
folks at AECL before writing his article. It's entirely a bunch of
opinions of his after he read Nancy Leveson's article on Therac.

> For
>example, he claims that this [perhaps] regenned rt11 monitor supports
>multi-threaded execution to the degree of its enabling things like race
>conditions, etc.

Heck, he also believes that PDP-11 assembly is *difficult*!

>just throwing it out there as discussion bait...

Again, don't take what he writes too seriously (after all, the author didn't -
look at all the "I believes" and "I feels" in there). I've worked with
several of the Therac machines, and any of the AECL engineers involved
knows a lot more about the methodology involved than the third-hand
opinions on someone's web site.

 Tim Shoppa                        Email:
 Trailing Edge Technology          WWW:
 7328 Bradley Blvd		   Voice: 301-767-5917
 Bethesda, MD, USA 20817           Fax:   301-767-5927
Received on Thu Sep 09 1999 - 15:58:51 BST

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