My personal evangalising (that computers in traveller aren't all that big compared to modern hardware) doesn't seem to go anywhere.
PC equivalent hardware disappears into things such as perscomms, where reliability and robustness aren't as important. Ship computers on the other hand are needed NOT to fail, especially in Jump, or landing, or any other critical time when loss of control and power can be fatal. You can only do this reliably with massive amounts of redundancy all throughout your control chain. Not only multiple computers, but multiple network paths, multiple routers, multiple power supplies, multiple environment controls and so on, as well as an overarching framework to keep track of everything and constantly test everything. In traveller this is lumped as "computer" rather then going into explicit detail.
Big mainframes still exist these days. They still have uses. With a couple of million dollars you can go out and buy one tommorow. Unless you have a use for that kind of computing power it isn't going to be cost effective for you, but the times that it is that investment can be quite worthwhile. Mag tape is still used, data density is enormous on Mag tape compared to hard drives, and a terrabyte stored on Mag Tape is incredibly cheap compared to reliable drives of that size.
Maybe I should just use a #standard_computing_rant instead.
IMTU both the Navy and Marines use jacks as the primary interface for pilots, with stick controls for those pilots that haven't been upgraded.