From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me X-Spam-Level: X-Spam-Status: No, score=-0.8 required=5.0 tests=BAYES_00,INVALID_DATE autolearn=no autolearn_force=no version=3.4.4 Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!think.com!spool.mu.edu!news.uu.net!convex!spray From: spray@convex.com (Rob Spray) Newsgroups: comp.lang.ada Subject: Re: Critique of SEI's Ada DARK project Message-ID: Date: 22 May 91 16:58:56 GMT Article-I.D.: convex.spray.674931536 References: <1991May22.143229.24667@src.honeywell.com> Sender: usenet@convex.com (news access account) Distribution: comp.lang.ada Organization: CONVEX Computer Corporation, Richardson, Tx., USA Nntp-Posting-Host: trojan.convex.com List-Id: In <1991May22.143229.24667@src.honeywell.com> vestal@SRC.Honeywell.COM (Steve Vestal) writes: >In article spray@convex.com (Rob Spray) writes: >Rob> One concern I have always had about DARK is how it got funded >Rob> targetted to a processor that is not available in a >Rob> radiation-hardened configuration. Several embedded systems >Rob> I am familiar with are required to use full MIL-SPEC processors. >Does mil-spec mean that a processor must be radiation hardened, or just that >it be class B, certain temperature range, certain packaging, etc.? "Radiation >hardened" isn't a yes/no thing; there are several parameters and several >degrees to radiation hardening. For example, of the two processors cited, I There's a MIL STD (5400 Class 1? I can't remember) that specifies hardness, altitude, temperature range etc, etc. It's my understanding that most air/spaceborne MCCR systems must use processors that meet that Standard (e.g. Loral(Rolm) Hawks, AN/UYK-xx, ap101, 1750A etc) >orbit, shuttle or space station in low orbit, and aircraft, all vary. Also, >this is a systems issue, since one can trade shielding against the radiation >insensitivity of the circuitry used. Not always true. Most RFPs specify the Standards to be met. Shielding non-qualified parts is not always an option. >There are Ada development environments and executives for rad-hard computer >systems, but I don't think a high degree of radiation insensitivity is a >universal requirement on all military systems. Agreed, but a significant number of systems have that requirement, so the choice of the 68K for DARK, effectively ignored many issues faced by builders of such systems. The 68K has a reasonably orthogonal architecture and good memory management scheme for distributed processing. From a compiler writer's view, lessons learned on a VAX transfer to the 68K. So the 68K had the best Ada environment to implement DARK. (I suspect that proposing a VAX target would have been even more unacceptable.) However, there are no rad-hard 68Ks, so technology transfer of DARK to a significant percentage of the intended systems is hindered. --Rob Spray --spray@convex.com --Previous disclaimer is still in full effect.