Few things are more valuable in war than the secrecy of long distance communications. Though we haven't been at a conflict which posed any credible threat for the better part of a century, holding on to technological advantages when they're fresh is in our best interest and in the best interest of the American Peace we have going.
It's fairly unfortunate that a majority of computer technology is imported from foreign manufacturers for many reasons, but export control isn't really one of them.
Supercomputers, yes ... general components... not particularly.
In a lot of ways 'modern' computer technology isn't all that essential. It certainly isn't present in a whole lot of our military hardware because of realities of acquiring and maintaining such hardware _and_ the lack of an exponential increase of computing needs to match capabilities.
In fewer words, computer technology is valuable, but not extremely so. Restricting the flow of anything remotely related to consumer computer tech wouldn't have much benefit, even if it were possible considering most of it is made in Asia.
Then just focus on basic computer technology. Restricting the export of semiconductors in the early 60s could have created a significant advantage for the US, but would be absurd to support a decision like that.
Military benefit alone is not enough to justify an export restriction, one has to consider the cost on society as a whole. The cost of restricting the export of cryptography is too large to justify.
The processors and basic hardware have been mostly commodity since the mid 90s, the interconnects and related technology have mostly been specialized hardware though you could always do grid computing with Ethernet and the like.
True. Things like the Crays have their own, specialized interconnects and OS (on work nodes). A lot of things that aren't trying to be in the top can use fiber channel for similar results, though.
