The military has loads of money to spend on technology, so you'd expect its computers to be gruntier than anything you're likely to get your filthy hands on -- right? Dr Carlo Kopp slips under the radar to investigate.
One of the most shameless myths created and perpetuated by Hollywood is the notion that military computers are somehow much more powerful and 'hi-tech' than those employed by home users and industry.
Nothing could be further from the truth. With the exception of a handful of highly specialised digital signal and data processing systems, most computers employed in military systems are one, two, three -- or even four -- generations behind in technology compared with their commercial cousins.
Now the latest generation of 'digitised' weaponry is making headlines we'll explore the specialised -- and in many respects very different world -- of military computers and how they are really used.
A different world?
The world of military computing is very different from the computing environments most of us are familiar with. In the broadest sense, the greatest distinction between specialised computing equipment for military and commercial users is that military computers must often survive in very harsh environments.
The first category of military computers is basic fixed base support machines, used for administrative, word processing and accounting work in fairly standard office environments.
Such machines are no different from their commercial cousins, although they're often must meet electromagnetic emission requirements such as the US NACSIM 5100 TEMPEST standard. While the machine might be a very ordinary PC, server or workstation, it cannot be allowed to leak Van Eck radiation from the monitor, or eaves-droppable emissions from its LAN and serial interfaces. So the Quartermaster's PC will probably be identical to the machine on your desk, but the spook's machine, or HQ wordprocessor, is likely to be the more expensive TEMPEST model.
The next step up the hierarchy of environmental resilience is the 'ruggedised' military computer. A ruggedised machine is a hybrid of commercial-grade electronic hardware, packaged in a Milspec or Military Standard (Mil-Std- in the US, STANAG in Europe) casing or chassis. The chassis will be made to comply with one or more military environmental standards and such machines are deployed in the field, or used in 'undemanding' airborne, land-mobile or naval environments with modest vibration, shock and temperature exposure.
Finally, we have military 'embedded' computers, designed from the ground up to survive in harsh environments, and fully compliant with the full gamut of military reliability standards. These are the processors that are installed in satellites, fighter planes, missiles, torpedoes, smart bombs and other military equipment and such machines may implement commercial, or specialised military instruction sets.
Reliability and Milspecs
The most important distinguishing feature of embedded military computing equipment is that it is designed for exceptional reliability in harsh environments -- something that has had a huge impact on how such machines are designed and constructed. The problem lies as much in making the chips and surrounding hardware more reliable, as it does in measuring the reliability of such components in particular environments including the testing combinations of temperature, humidity and vibration load.
It's vital to mission success that reliability can be predicted and measured in complex military equipment and plenty of examples exist where high tech systems failed in combat because they were less reliable than they needed to be. If a missile is bearing down on you the last thing you need or want is for the 'fault' light to start flashing on the computer controlling your jamming equipment.
Determining the reliability of an electronic component such as a processor chip or connector can be an expensive and time consuming chore -- indeed this is one of the underlying reasons why modern military equipment is often worth its weight in gold, or more!
To understand why, it is helpful to digress a little into failure mechanisms in electronic components, an area which, like basic reliability theory, is sadly not taught in most Australian university engineering and computer science courses any more. As we invest most of our engineering and computer science talent into supporting equipment -- rather than designing it -- this is all the more an incongruity in the scheme of things.
Electrical failures in components result typically from dielectric breakdowns in insulators, mechanical open and short circuits, migration effects in semiconductor PN junctions, and migration effects in metal. To these we can also add the insidious effects of corrosion in materials.
Without delving too deeply into the materials science behind these effects, we can state that all of these phenomena are accelerated in effect by shock, vibration, temperature, temperature changes, humidity and the presence of corrosive agents such as salt or chemicals left over from production processes.
Temperature alone can be destructive because it accelerates the diffusion of dopants in semiconductors and over a period of time this will result in semiconductor junction dopant gradients -- the reason why transistors work in the first place -- flattening out to the point where the junction ceases to be a junction and the component fails. High temperatures also accelerate the migration of metal between connections or chips, causing eventual short circuits.
Temperature changes cause mechanical expansion and contraction, leading to all manner of turmoil, from printed circuit board delamination, through printed circuit board hole and via connections shearing off, to pins on packages or connectors developing metal fatigue.Vibration and shock cause straight mechanical failures, or metal fatigue. A particularly nasty manifestation of vibration is the stressful flexing of flexural modes in printed circuit boards, not unlike those on your stereo system woofer. Flex a printed circuit board enough and it will delaminate or components will start popping off it.
Humidity is insidious in its effects: it reduces the effectiveness of cooling systems and also precipitates on components during rapid temperature changes. In turn this produces an electrolyte for dissimilar metals and production residues on components, thus facilitating corrosion.
Clearly all three of these basic environmental factors, temperature/changing temperature, vibration/shock and humidity, are damaging within themselves, and also mutually supportive in impairing the reliability of any piece of equipment. Needless to say, this is true of commercial and military equipment. The big difference of course between the two contexts is that one simply increases costs and cuts profit margins -- whereas the other costs lives and loses battles.
When military tech goes wrong, it can go fatally wrong: in 1979, a US attempt to extract hostages from Teheran failed when the use of 'support' category-rated minesweeping helicopters designed for two hour sorties, instead of highly reliable combat search and rescue helicopters designed for 12 hour sorties, caused a mission failure and loss of lives. Another fatal example was the sinking of at least one Royal Navy destroyer in the 1982 Falklands war, due to an intermittently failing missile launcher. Read Ashton Mill's Technica Obscura column this month for more military and civilian computer SNAFUs.
When we want to launch electronics into orbit on a satellite, we also have to take into account the highly destructive effects of
Issue: 107 | December, 2009