For some reason many people think the displacement tonnage devoted to computers on starships reflects the massive computers of the 1970s. I have never understood this. Why would computers in the “Far Future” look like computers from the 1970s? Even in 1977 when I first bought Classic Traveller I never assumed the space required for computers was taken up with one large computer with spinning tape reels.
The displacement tonnage of the computer isn’t for “the computer” alone. It is the space devoted on the ship to the computer system.
Starships in Traveller travel parsecs away from facilities that can handle repairs of starships. They travel to worlds (often) where the technology level is far below the needs that might be required to repair their computer. Starships in Traveller can be attacked by other ships when entering into a new system. These attacks can damage any element of the ship — including the computer system. The computer system in Traveller starships handle many functions, but one of the most important is handling the Generate program or running the Navigation programs that allow the ship to track and navigate from star system to star system and arrive close enough in a system to the system starport that the ship can dock before running out of life support but not so close that the ship is destroyed by a world’s gravity well when coming out of jump space. The storage of the programs of data for these programs alone must be monstrous. If the computer system is damaged and there is no facility to repair it, there is no way to leave a system. A crew and passengers might not be going home for a long while… if at all. (Which is awesome for Traveller play, by the way! But not something most folks traveling on a starship would want to encourage.)
The volume dedicated to the computer, as I see it, constitutes redundancies of multiple computer systems, space for accessing those systems, armor around the computer systems to prevent damage from attacks, cushioning and packing to protect the system on hard landings.
I understand there are people who would, apparently, head off light years from the closest repair facilities into the coldness of space knowing they might take missile or laser fire damage or have a bad landing on a planet or end up in a system without any computer technology at all… and yet still want to attempt such travel with nothing but a laptop sitting on their ship’s console to get them there and back.
I am not one of those people. And I would never get on such a person’s person’s ship.
[As a side note: The term “Jump Tapes” never appears in the rules. The item is called a Jump Cassette, and whether this cassette holds a tape, crystals, gears, a magnetic pulse, or any other method of interacting with the ship’s computer is never defined…]