Re: Critique of SEI's Ada DARK project

[vestal@SRC.Honeywell.COM (Steve Vestal)]

In article <spray.674858011@convex.convex.com> 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
am aware that there is a very rad-hard version of the 1750A.  As far as I
know, there are versions of the i80x86 family that are perhaps less sensitive
to radiation in some ways than commercial parts (e.g. maybe tolerate somewhat
greater total dose) but may or may not have significantly better numbers in
all respects (e.g. sensitivity to single event upset).  My speculation would
be that radiation hardening requirements for communication sattelites in high
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.

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.

Steve Vestal
Mail: Honeywell S&RC MN65-2100, 3660 Technology Drive, Minneapolis MN 55418 
Phone: (612) 782-7049                    Internet: vestal@src.honeywell.com